Analysis of the common C282Y and H63D mutations in the HFE gene is widely used to diagnose hereditary hemochromatosis (HH). The aim of this study was to evaluate the efficiency with which different hospitals and general practitioners select patients for HH genot
ype and to determine the distribution of HFE mutations in such patients. Nine hundred unrelated patients from Danish hospitals and general practitioners (group A) and 69 consecutive patients from a specialized liver unit (group B) were examined for HFE substitutions using multiplex real-time polymerase chain reaction. In group A we found 13.0% (0%) C282Y homozygotes, 5.8% (2.6%) H63D/C282Y compound heterozygotes and 1.9% (3.1%) S65C heterozygotes. The values for 420 Danish blood donors are shown in parentheses. The distribution of genotypes in group B was similar to that of the blood donors. Serum ferritin, transferrin iron saturation and pathological data were collected from 38 randomly selected C282Y homozygotes, 36 H63D/C282Y compound heterozygotes, 19 H63D heterozygotes, 17 S65C heterozygotes and 144 wild-types. All of the C282Y homozygotes and 28% of the compound heterozygotes were diagnosed as HH patients. There was no evidence of HH in the H63D homozygotes or S65C heterozygotes. Moreover, 7 wild-type patients, 2 C282Y heterozygote patients and one H63D heterozygote patient fulfilled the criteria for HH. The significant enrichment of HH among associated genotype samples submitted for HFE testing indicates that the clinical selection is generally adequate. However, the study showed substantial deviation in the selection efficiency among the various hospitals and general practitioners.
Ulbricht A, etal., Curr Biol. 2013 Mar 4;23(5):430-5. doi: 10.1016/j.cub.2013.01.064. Epub 2013 Feb 21.
Mechanical tension is an ever-present physiological stimulus essential for the development and homeostasis of locomotory, cardiovascular, respiratory, and urogenital systems. Tension sensing contributes to stem cell differentiation, immune cell recruitment, and tumorigenesis. Yet, how mechanical sig
nals are transduced inside cells remains poorly understood. Here, we identify chaperone-assisted selective autophagy (CASA) as a tension-induced autophagy pathway essential for mechanotransduction in muscle and immune cells. The CASA complex, comprised of the molecular chaperones Hsc70 and HspB8 and the cochaperone BAG3, senses the mechanical unfolding of the actin-crosslinking protein filamin. Together with the chaperone-associated ubiquitin ligase CHIP, the complex initiates the ubiquitin-dependent autophagic sorting of damaged filamin to lysosomes for degradation. Autophagosome formation during CASA depends on an interaction of BAG3 with synaptopodin-2 (SYNPO2). This interaction is mediated by the BAG3 WW domain and facilitates cooperation with an autophagosome membrane fusion complex. BAG3 also utilizes its WW domain to engage in YAP/TAZ signaling. Via this pathway, BAG3 stimulates filamin transcription to maintain actin anchoring and crosslinking under mechanical tension. By integrating tension sensing, autophagosome formation, and transcription regulation during mechanotransduction, the CASA machinery ensures tissue homeostasis and regulates fundamental cellular processes such as adhesion, migration, and proliferation.
Alexander J and Kowdley KV, Genet Med. 2009 May;11(5):307-13. doi: 10.1097/GIM.0b013e31819d30f2.
In populations of northern European descent, the p.C282Y mutation in the HFE gene is highly prevalent, and HFE-associated hereditary hemochromatosis is the most common type of inherited iron overload disorder. Inappropriate
low secretion of hepcidin, which negatively regulates iron absorption, is postulated to be the mechanism for iron overload in this condition. The characteristic biochemical abnormalities are elevated serum transferrin-iron saturation and serum ferritin. Typical clinical manifestations include cirrhosis, liver fibrosis, hepatocellular carcinoma, elevated serum aminotransferase levels, diabetes mellitus, restrictive cardiomyopathy and arthropathy of the second and third metacarpophalangeal joints. Most patients are now diagnosed before the development of these clinical features. Molecular genetic tests are currently available for genotypic diagnosis. In selected individuals, diagnosis might require liver biopsy or quantitative phlebotomy. Iron depletion by phlebotomy is the mainstay of treatment and is highly effective in preventing the complications of iron overload if instituted before the development of cirrhosis. Genetic testing is currently not recommended for population screening because of low yield as the majority of the healthy, asymptomatic p.C282Y homozygotes do not develop clinically significant iron overload. HFE gene testing remains an excellent tool for the screening of first-degree relatives of affected probands who are p.C282Y homozygotes.
Viola A, etal., Leuk Lymphoma. 2006 Nov;47(11):2331-4.
An increased incidence of HFE gene mutations has been described in hematologic malignancies. In the present study, we investigated the allelic frequency of HFE gene mutations in 154 adult patients with acute leukemia (AL) [
107 acute myeloid leukemia (AML), 20 acute promyelocytic leukemia (APL) and 27 acute lymphoblastic leukemia (ALL)]. The allelic frequency of the H63D mutation was 29% in AL patients and 25% in the healthy controls [P = 0.41; odds ratio (OR) = 1.20; 95% confidence interval (CI) = 0.77 - 1.93]. No difference was found between controls and AML or APL patients, whereas the H63D mutation was significantly more frequent in ALL than controls (44% vs. 25%, P = 0.04; OR = 2.37; 95% CI = 1.05 - 5.36). The overall comparison of the mutation among the three subtypes of AL demonstrated a higher allelic frequency in ALL (P = 0.02). In conclusion, our data demonstrate a correlation between the presence of the H63D mutation and the occurrence of ALL in adult patients.
Oliveira TM, etal., Braz J Med Biol Res. 2006 Dec;39(12):1575-80.
Hereditary hemochromatosis is a disorder of iron metabolism characterized by increased iron intake and progressive storage and is related to mutations in the HFE gene. Interactions between thalassemia and hemochromatosis may further increase iron overload. The
ethnic background of the Brazilian population is heterogeneous and studies analyzing the simultaneous presence of HFE and thalassemia-related mutations have not been carried out. The aim of this study was to evaluate the prevalence of the H63D, S65C and C282Y mutations in the HFE gene among 102 individuals with alpha-thalassemia and 168 beta-thalassemia heterozygotes and to compare them with 173 control individuals without hemoglobinopathies. The allelic frequencies found in these three groups were 0.98, 2.38, and 0.29% for the C282Y mutation, 13.72, 13.70, and 9.54% for the H63D mutation, and 0, 0.60, and 0.87% for the S65C mutation, respectively. The chi-square test for multiple independent individuals indicated a significant difference among groups for the C282Y mutation, which was shown to be significant between the beta-thalassemia heterozygote and the control group by the Fisher exact test (P value = 0.009). The higher frequency of inheritance of the C282Y mutation in the HFE gene among beta-thalassemic patients may contribute to worsen the clinical picture of these individuals. In view of the characteristics of the Brazilian population, the present results emphasize the need to screen for HFE mutations in beta-thalassemia carriers.
Putova I, etal., Cas Lek Cesk. 2005;144(6):391-7; discussion 397-8.
BACKGROUND: Hereditary hemochromatosis is one of the most common autosomal recessive diseases. Aim of the study. 1. To establish frequency of C282Y and H63D mutations in the HFE gene (the hemochromatosis gene) in general population of the Czech Republic and in p
atients with hemochromatosis. 2. To find out whether hemochromatosis in homo- or heterozygous state plays a role in the pathogenesis of rheumatic diseases. METHODS AND RESULTS: In 32 patients with hereditary hemochromatosis, in 84 patients with polymyositis or dermatomyositis, in 246 patients with juvenile idiopathic arthritis and in 481 persons of the control group the presence of HFE gene mutations was etablished. The HFE gene mutations were screened for by restriction enzyme analysis performed on PCR amplified products. In the control group, 6.86% carriers of the C282Y mutation and 26.61% those of H63D were found. Homozygous C282Y or H63D mutation was found in 90.6% (p<0.001) of patients with hemochromatosis. Heterozygous C282Y mutation was found in 12.2% (p<0.05) of patients with juvenile idiopathic arthritis. We didn't detected higher prevalence of HFE gene mutations in patients with polymyositis and dermatomyositis. CONCLUSIONS: Results of this study show that heterozygosity for C282Y mutation may be a risk factor for juvenile idiopathic arthritis but not for polymyositis and dermatomyositis.
Allen KJ, etal., N Engl J Med. 2008 Jan 17;358(3):221-30. doi: 10.1056/NEJMoa073286.
BACKGROUND: Most persons who are homozygous for C282Y, the HFE allele most commonly asssociated with hereditary hemochromatosis, have elevated levels of serum ferritin and transferrin saturation. Diseases related to iron overload develop in some C282Y homozygote
s, but the extent of the risk is controversial. METHODS: We assessed HFE mutations in 31,192 persons of northern European descent between the ages of 40 and 69 years who participated in the Melbourne Collaborative Cohort Study and were followed for an average of 12 years. In a random sample of 1438 subjects stratified according to HFE genotype, including all 203 C282Y homozygotes (of whom 108 were women and 95 were men), we obtained clinical and biochemical data, including two sets of iron measurements performed 12 years apart. Disease related to iron overload was defined as documented iron overload and one or more of the following conditions: cirrhosis, liver fibrosis, hepatocellular carcinoma, elevated aminotransferase levels, physician-diagnosed symptomatic hemochromatosis, and arthropathy of the second and third metacarpophalangeal joints. RESULTS: The proportion of C282Y homozygotes with documented iron-overload-related disease was 28.4% (95% confidence interval [CI], 18.8 to 40.2) for men and 1.2% (95% CI, 0.03 to 6.5) for women. Only one non-C282Y homozygote (a compound heterozygote) had documented iron-overload-related disease. Male C282Y homozygotes with a serum ferritin level of 1000 mug per liter or more were more likely to report fatigue, use of arthritis medicine, and a history of liver disease than were men who had the wild-type gene. CONCLUSIONS: In persons who are homozygous for the C282Y mutation, iron-overload-related disease developed in a substantial proportion of men but in a small proportion of women.
Chio A, etal., Neurobiol Aging. 2015 Oct;36(10):2906.e7-11. doi: 10.1016/j.neurobiolaging.2015.06.016. Epub 2015 Jun 18.
It has been recently reported that the p.His63Asp polymorphism of the HFE gene accelerates disease progression both in the SOD1 transgenic mouse and in amyotrophic lateral sclerosis (ALS) patients. We have evaluated the effect of HFE
FE p.His63Asp polymorphism on the phenotype in 1351 Italian ALS patients (232 of Sardinian ancestry). Patients were genotyped for the HFE p.His63Asp polymorphism (CC, GC, and GG). All patients were also assessed for C9ORF72, TARDBP, SOD1, and FUS mutations. Of the 1351 ALS patients, 363 (29.2%) were heterozygous (GC) for the p.His63Asp polymorphism and 30 (2.2%) were homozygous for the minor allele (GG). Patients with CC, GC, and GG polymorphisms did not significantly differ by age at onset, site of onset of symptoms, and survival; however, in SOD1 patients with CG or GG polymorphism had a significantly longer survival than those with a CC polymorphism. Differently from what observed in the mouse model of ALS, the HFE p.His63Asp polymorphism has no effect on ALS phenotype in this large series of Italian ALS patients.
BACKGROUND/AIMS: Very little is known about the HFE gene in the rat. The aim of the present study was to determine: (1) the structure of the rat HFE gene; and (2) the tissue expression of the HFE
FE mRNA in the rat, with special emphasis on the liver. METHODS: Cloning of the rat HFE gene was performed using library screening and PCR. Exon-intron borders were assigned by DNA sequencing. Parenchymal and non-parenchymal liver cells were isolated by fractionation of normal rat liver. HFE mRNA levels were determined by Northern blot (tissues) and real-time PCR (isolated liver cells). RESULTS: The rat HFE gene contained six exons and five introns. The HFE gene is expressed in multiple tissues in the rat, including bone marrow, with the highest expression in the liver. We observed HFE transcripts in several categories of isolated rat liver cells. Unexpectedly, expression also occurred in rat hepatocytes. CONCLUSIONS: The exon-intron pattern of the HFE gene is strongly conserved between rat and mouse. The pattern of tissue expression of the HFE gene is rather similar in humans and rodents. The finding of HFE gene expression in rat hepatocytes raises interesting questions regarding its role in the hepatocyte iron metabolism.
Jazayeri M, etal., Eur J Haematol. 2003 Dec;71(6):408-11.
OBJECTIVES: Beta-thalassaemia minor (BTM) alone does not lead to iron overload, however, some gene modifiers and acquired causes are reported. When it is inherited together with a mutation in the HFE (HLA-H) gene associated with hereditary haemochromatosis, iron
overload may ensue. To analyse the relationship between iron status and HFE mutations in Iranian BTM patients, we compared the frequency of the C282Y and H63D HFE mutations and ferritin level in a group of BTM patients from the National Thalassaemia Transfusion and Care Centre with that of healthy individuals. PATIENTS AND METHODS: Ninety-three (56 females) documented BTM cases and 104 (54 females) controls were enrolled in the study. Serum ferritin level was measured in all subjects by immuno-radiometric assay and HFE genotypes were determined using restriction fragment length polymorphism analysis of PCR-amplified HFE gene fragment. RESULTS: Eighteen (19.4%) BTM patients vs. 12 (11.5%) controls were H63D heterozygotes, while there were three (3.2%) cases and three (2.9%) controls with H63D homozygosity. All three C282Y mutations were found in BMT patients with one of them being a compound heterozygote. A significant difference was observed in the total number of HFE mutations in favour of BTM patients over the controls (P < 0.05, OR = 2.064). The H63D and C282Y allele frequencies were 12.9 and 1.61 in patients and 8.65 and 0 in controls, respectively. The mean ferritin level in cases with HFE mutations showed no significant difference from that of the patients without mutations (P > 0.05). CONCLUSIONS: Our results suggest that HFE mutations C282Y and H63D are more frequent in Iranian BTM patients than in the normal population, causing no significant changes in serum ferritin level.
Barton JC, etal., Gene. 2015 Dec 15;574(2):179-92. doi: 10.1016/j.gene.2015.10.009. Epub 2015 Oct 9.
The hemochromatosis gene HFE was discovered in 1996, more than a century after clinical and pathologic manifestations of hemochromatosis were reported. Linked to the major histocompatibility complex (MHC) on chromosome 6p, HFE
n> encodes the MHC class I-like protein HFE that binds beta-2 microglobulin. HFE influences iron absorption by modulating the expression of hepcidin, the main controller of iron metabolism. Common HFE mutations account for ~90% of hemochromatosis phenotypes in whites of western European descent. We review HFE mapping and cloning, structure, promoters and controllers, and coding region mutations, HFE protein structure, cell and tissue expression and function, mouse Hfe knockouts and knockins, and HFE mutations in other mammals with iron overload. We describe the pertinence of HFE and HFE to mechanisms of iron homeostasis, the origin and fixation of HFE polymorphisms in European and other populations, and the genetic and biochemical basis of HFE hemochromatosis and iron overload.
Genetic hemochromatosis (GH) is associated with two mutations of the HFE gene (Cys282Tyr and His63Asp). Heterozygosity for GH is associated with a mild increase in iron metabolism parameters, and increased iron stores are associated with abnormal glucose toleran
ce and decreased insulin sensitivity in the general population. We have previously shown that the frequency of the two HFE mutations is not increased in patients with type 2 diabetes. However, to assess whether the presence of HFE mutations modulates the clinical presentation of type 2 diabetes, we studied the clinical characteristics and iron metabolism indexes according to the presence of the two mutations in 266 patients with type 2 diabetes. The Cys282Tyr mutation and the His63Asp mutation were present in 9. 8% and 26% of the patients, respectively. Serum iron, transferrin saturation and ferritin concentrations were significantly increased in patients expressing either HFE mutations, compared to those without any mutation. There was no difference in the clinical characteristics in the two groups except that obesity was significantly less frequent in the patients with at least one mutation than in those without any mutation (27.6% vs 42.8%, p=0.02). This finding suggests that, in the absence of obesity, HFE mutations, through the insulin resistance associated with the increase in iron stores, may contribute to the onset of type 2 diabetes.
In the present paper, we describe a patient who is a compound heterozygote for three mutations in the HFE gene: C282Y, H63D, and E168Q. The patient's mother carries two copies of H63D and one copy of E168Q; the patient's father is heterozygous for C282Y. The fam
ily study indicates that the patient, as well as his sister, a maternal uncle, and a first cousin, all have inherited a single HFE allele that contains two mutations H63D and E168Q. The clinical symptoms and laboratory findings of the patient and his relatives are consistent with the conclusion that the E168Q mutation by itself is unlikely to result in hemochromatosis.
De Falco L, etal., Am J Hematol. 2018 Mar;93(3):383-393. doi: 10.1002/ajh.24991. Epub 2017 Dec 18.
We investigated the role of HFE C282Y, H63D, and TMPRSS6 A736V variants in the pathogenesis of iron deficiency anemia (IDA) in celiac disease (CD) patients, at diagnosis and after 1 year of gluten-free diet (GFD). Demographic and clinical features were prospecti
vely recorded for all CD patients between 2013 and 2017. C282Y, H63D, and A736V variants were evaluated for CD patients and controls. Finally, 505 consecutive CD patients and 539 age-matched control subjects were enrolled. At diagnosis, 229 CD subjects had IDA (45.3%), with a subgroup of anemic patients (45.4%) presented persistent IDA at follow-up. C282Y allele frequency was significantly increased in CD compared with controls (1.1% vs 0.2%, P = .001), whereas H63D and A736V allele frequencies were similar among patients and controls (P = .92 and .84, respectively). At diagnosis, C282Y variant in anemic CD patients was significantly increased compared to nonanemic group (2% and 0.5%, P = .04). At follow-up, A736V was significantly increased in IDA persistent than in IDA not persistent (57.7% vs 35.2%, P < .0001). CD patients with H63D mutation showed higher Hb, MCV, serum iron, and ferritin levels than subjects without HFE mutations. Decreased hepcidin values were observed in anemic compared to nonanemic subjects at follow-up (1.22 ± 1.14 vs 2.08 ± 2.15, P < .001). This study suggests a protective role of HFE in IDA CD patients and confirms the role of TMPRSS6 in predicting oral iron response modulating hepcidin action on iron absorption. Iron supplementation therapeutic management in CD could depend on TMPRSS6 genotype that could predict persistent IDA despite iron supplementation and GFD.
BACKGROUND AND OBJECTIVES: Hereditary hemochromatosis (HH) is an autosomal recessive disorder of iron metabolism. The HFE gene implicated in this disorder has been identified on chromosome 6 (6p21.3). The most prevalent mutation in HH patients changes the 282 cy
steine residue to tyrosine (C282Y). The role of a second mutation which changes the 63 histidine to aspartic acid (H63D) in iron overload has been controversial. The aim of this study was to evaluate the effect of the H63D mutation on the ferritin levels of beta-thalassemia carriers. DESIGN AND METHODS: beta-thalassemia carriers have a tendency to increase iron absorption because of mild anemia and slightly increased erythropoiesis. Differences in ferritin levels between homozygotes for H63D and wild type may indicate a modulator effect of the HFE mutation on iron absorption. We studied 152 healthy males, heterozygous for beta-thalassemia. Serum ferritin was measured by chemiluminescence. H63D genotypes were determined by digestion of polymerase chain reaction (PCR) products with MboI restriction enzyme. RESULTS: Forty-five subjects were H63D heterozygotes and four subjects were H63D homozygotes. Ferritin levels were (mean +/- SD): 250 +/- 138 microg/L in homozygotes for the wild type H/H; 295 +/- 186 microg/L in H/D heterozygotes; and 389 +/- 75 microg/L in homozygotes for the mutation D/D. The difference in ferritin values between H/H and D/D is statistically significant (p=0.022). INTERPRETATION AND CONCLUSIONS: beta-thalassemia carriers who are homozygotes for the H63D mutation have higher ferritin levels than beta-thalassemia carriers with the H/H genotype, suggesting that the H63D mutation may have a modulating effect on iron absorption.
Beutler E, etal., Lancet. 2002 Jan 19;359(9302):211-8.
BACKGROUND: There has been much interest in screening populations for disease-associated mutations. A favoured candidate has been the HFE gene, mutations of which are the most common cause of haemochromatosis in the European population. About five people in 100
0 are homozygotes for the 845G-->A mutation, but little is known of how many have mutation-caused clinical manifestations. METHODS: We screened 41038 individuals attending a health appraisal clinic in the USA for the 845G--> A and 187C-->G HFE mutations, and analysed laboratory data and data on signs and symptoms of haemochromatosis as elicited by questionnaire. FINDINGS: The most common symptoms of haemochromatosis, including poor general health, diabetes, arthropathies, arrhythmias, impotence, and skin pigmentation were no more prevalent among the 152 identified homozygotes than among the controls. The age distribution of homozygotes and compound heterozygotes did not differ significantly from that of controls: there was no measurable loss of such individuals from the population during ageing. However, there was a significantly increased prevalence of a history of hepatitis or "liver trouble" among homozygotes and in the proportion of homozygotes with increased concentrations of serum aspartate aminotransferase and collagen IV; these changes were not related to iron burden or to age. Only one of the 152 homozygotes had signs and symptoms that would suggest a diagnosis of haemochromatosis. INTERPRETATION: The normal age distribution of people with the haemochromatosis genotype, and the lack of symptoms in patients of all ages, indicate that the penetrance of hereditary haemochromatosis is much lower than generally thought. The clinical penetrance of a disorder is an essential consideration in screening for genetic disease; disorders with low penetrance are more expensive candidates for screening than disorders with high penetrance. Our best estimate is that less than 1% of homozygotes develop frank clinical haemochromatosis.
Kallianpur AR, etal., Cancer Epidemiol Biomarkers Prev. 2004 Feb;13(2):205-12.
Individuals with the major hemochromatosis (HFE) allele C282Y and iron overload develop hepatocellular and some extrahepatic malignancies at increased rates. No association has been previously reported between the C282Y allele and breast cancer. We hypothesized
that due to the pro-oxidant properties of iron, altered iron metabolism in C282Y carriers may promote breast carcinogenesis. Because 1 in 10 Caucasians of Northern European ancestry carries this allele, any impact it may have on breast cancer burden is potentially great. We determined C282Y genotypes in 168 patients who underwent high-dose chemotherapy and blood cell transplantation for cancer: 41 with breast cancer and 127 with predominantly hematological cancers (transplant cohort). Demographic, clinical, and tumor characteristics were reviewed in breast cancer patients. The frequency of C282Y genotypes in breast cancers was compared with the frequency in nonbreast cancers, an outpatient sample from Tennessee (n = 169), and a published United States national sample. The frequency of at least one C282Y allele in breast cancers was higher (36.6%, 5 homozygotes/10 heterozygotes) than frequencies in Tennessee (12.7%, P < 0.001), the general population (12.4%, P < 0.001), and similarly selected nonbreast cancers (17.0%, P = 0.008). The likelihood of breast cancer in the transplant cohort increased with C282Y allele dose (P(trend) = 0.010). These results were supported by the finding in a nontransplant cohort of a higher frequency of C282Y mutations in Caucasian (18.4%, P = 0.039) and African-American (8.5%, P = 0.005) women with breast cancer than race-specific national frequency estimates. A high prevalence of C282Y alleles in women with breast cancer with and without poor risk features suggests that altered iron metabolism in C282Y carriers may promote the development of breast cancer and/or more aggressive forms of the disease.
Zamboni P, etal., Free Radic Biol Med. 2006 May 15;40(10):1869-73. Epub 2006 Feb 14.
Chronic venous stasis determines red blood cell extravasation and either dermal hemosiderin deposits or iron-laden phagocytes. Several authors have suspected that iron could play a role in the pathogenesis of venous leg ulcers. They hypothesized that local iron overload could generate free radicals
or activate a proteolytic hyperactivity on the part of metalloproteinases (MMPs) or else down-regulate tissue inhibitors of MMPs. However, they were unable to explain why iron deposits, visible in the legs of patients with chronic venous disease (CVD), cause lesions in only some individuals, whereas in others they do not. We hypothesized that such individual differences could be genetically determined and investigated the role of the C282Y and H63D mutations of the HFE gene. C282Y mutation significantly increases the risk of ulcer in primary CVD more than six times (OR = 6.69; 1.45-30.8; p = 0.01). Patients carrying the H63D variant have an earlier age of ulcer onset, by almost 10 years (p > 0.004). The increased risk of skin lesion and the early age of onset of the disease in HFE carriers confirm in a clinical setting that intracellular iron deposits of mutated macrophages have less stability than those of the wild type. We hypothesize that the physiologic iron protective mechanisms are affected by the HFE mutations and should be investigated in all diseases characterized by the combination of iron overload and inflammation.
Thenie AC, etal., Hum Mol Genet. 2001 Aug 15;10(17):1859-66.
Hereditary haemochromatosis is an autosomal recessive disease which results in iron overload, and it is the most frequently inherited disorder in Caucasian populations. The gene involved (HFE) has recently been identified, and it encodes an MHC class I-like mole
cule. A 2.7 kb cDNA has been isolated, whereas the HFE gene expression is characterized by an almost ubiquitous mRNA of 4.1 kb in size. The difference between this transcript and the isolated cDNA has not yet been explained. Thus, the 5' end of the HFE gene is still undefined and very little is known about the regulation of its expression. By searching this end, we isolated an antisense transcript originating from the same gene locus. Further investigations (rapid amplification of cDNA ends, RT-PCR experiments and dbEST screening) indicated that this RNA spans exon 1, exon 2, part of intron 1 of the HFE gene and approximately 1 kb upstream of it. This HFE antisense transcript is polyadenylated but displays no open reading frame. A ribonuclease A protection assay definitively demonstrated the biological existence of the HFE antisense RNA, which appears to be expressed in all of the tissues and cell lines tested. Furthermore, in vitro coupled transcription-translation experiments revealed that the HFE expression is decreased by this antisense RNA, indicating that it may play a critical role in the regulation of the HFE gene expression.
The risk of hemochromatosis-related morbidity is unknown among HFE compound heterozygotes (C282Y/H63D). We used a prospective population-based cohort study to estimate the prevalence of elevated iron indices and hemochromatosis-related morbidity for compound het
erozygotes. In all, 31,192 subjects of northern European descent were genotyped for HFE C282Y and H63D. An HFE-genotype stratified random sample of 1,438 subjects, followed for an average of 12 years to a mean age of 65 years, completed questionnaires and gave blood. Clinical examinations were blinded to HFE genotype. A total of 180 (84 males) clinically examined C282Y/H63D participants were compared with 330 (149 males) controls with neither HFE mutation; 132 (65 males) and 270 (122 males), respectively, had serum iron measures at both timepoints. Mean serum ferritin (SF) and transferrin saturation (TS) were significantly greater for male and female compound heterozygotes than for wild-types at baseline and follow-up (all P < 0.02) except for females who were premenopausal at baseline, where SF was similar in both genotype groups. For subjects with serum measures from both baseline and follow-up, mean SF and TS levels did not change significantly for men or for postmenopausal women, but for premenopausal women SF levels increased from 43 to 109 microg/L for compound heterozygotes and from 35 to 64 microg/L for wild-types (both P < 0.001). Male and female compound heterozygotes had a similar prevalence of hemochromatosis-related morbidity to wild-types. One of 82 males and zero of 95 females had documented iron overload-related disease. CONCLUSION: For male compound heterozygotes, mean iron indices do not change during middle age but for female compound heterozygotes menopause results in increased mean SF. Although compound heterozygotes might maintain elevated iron indices during middle age, documented iron overload-related disease is rare.
Frýdlová J, etal., Am J Physiol Gastrointest Liver Physiol. 2018 Oct 1;315(4):G560-G568. doi: 10.1152/ajpgi.00070.2018. Epub 2018 Jun 21.
Although the relationship between hereditary hemochromatosis and mutations in the HFE gene was discovered more than 20 years ago, information on the in vivo regulation of HFE protein expression is still limited. The purpose
of the study was to determine the response of liver HFE protein content to iron deficiency in mice and rats by immunoblotting. Attempts to visualize the HFE protein in whole liver homogenates were unsuccessful; however, HFE could be detected in liver microsomes or in plasma membrane-enriched fractions. Five-week-old male C57BL/6 mice fed an iron-deficient diet for 4 wk presented with a significant decrease in liver iron content and liver Hamp expression, as well as with a significant decrease in liver HFE protein content. Rats fed an iron-deficient diet for 4 wk also displayed significant decrease in liver Hamp expression and liver HFE protein content. These results suggest that the downregulation of HFE-dependent signaling may contribute to decreased Hamp gene expression in states of prolonged iron deficiency. It has recently been proposed that HFE protein could be a potential target of matriptase-2, a hepatocyte protease mutated in iron-refractory iron deficiency anemia. However, immunoblot analysis of HFE protein in the livers from Tmprss6-mutated mask mice did not show evidence of matriptase-2-dependent HFE protein cleavage. In addition, no indication of HFE protein cleavage was seen in iron-deficient rats, whereas the full-length matriptase-2 protein content in the same animals was significantly increased. These results suggest that HFE is probably not a major physiological target of matriptase-2. NEW & NOTEWORTHY Feeding of iron-deficient diet for 4 wk decreased liver HFE protein content in both mice and rats, suggesting that decreased HFE-dependent signaling may contribute to hepcidin downregulation in iron deficiency. There was no difference in HFE protein band appearance between matriptase-2-mutated mask mice and wild-type mice, indicating that HFE is probably not a major physiological substrate of matriptase-2-mediated protease activity in vivo.
Sangiuolo F, etal., Eur Respir J. 2015 Feb;45(2):483-90. doi: 10.1183/09031936.00104814. Epub 2014 Dec 10.
In idiopathic pulmonary fibrosis (IPF), lung accumulation of excessive extracellular iron and macrophage haemosiderin may suggest disordered iron homeostasis leading to recurring microscopic injury and fibrosing damage. The current study population comprised 89 consistent IPF patients and 107 contro
ls. 54 patients and 11 controls underwent bronchoalveolar lavage (BAL). Haemosiderin was assessed by Perls' stain, BAL fluid malondialdehyde (MDA) by high-performance liquid chromatography, BAL cell iron-dependent oxygen radical generation by fluorimetry and the frequency of hereditary haemochromatosis HFE gene variants by reverse dot blot hybridisation. Macrophage haemosiderin, BAL fluid MDA and BAL cell unstimulated iron-dependent oxygen radical generation were all significantly increased above controls (p<0.05). The frequency of C282Y, S65C and H63D HFE allelic variants was markedly higher in IPF compared with controls (40.4% versus 22.4%, OR 2.35, p=0.008) and was associated with higher iron-dependent oxygen radical generation (HFE variant 107.4+/-56.0, HFE wild type (wt) 59.4+/-36.4 and controls 16.7+/-11.8 fluorescence units per 10(5) BAL cells; p=0.028 HFE variant versus HFE wt, p=0.006 HFE wt versus controls). The data suggest iron dysregulation associated with HFE allelic variants may play an important role in increasing susceptibility to environmental exposures, leading to recurring injury and fibrosis in IPF.
Zhang M, etal., Asian Pac J Cancer Prev. 2015;16(11):4633-9.
BACKGROUND: Previous studies suggested that the H63D and C282Y polymorphisms in the HFE genes were susceptible to many cancer types, nevertheless, the present results were inconclusive. Thus, the present study was aimed to evaluate the association between the ... (more)
pan style='font-weight:700;'>HFE polymorphisms (H63D and C282Y) and cancer risk via meta-analysis. MATERIALS AND METHODS: We retrieved PubMed, Google Scholar, Embase and Web of Science databases for all eligible studies up to April 1, 2015. All the statistical analysis was conducted by STATA 12.0. RESULTS: Finally, a total of 20 publications including 24 case-control studies, comprising 6,524 cases and 31,080 controls for HFE-C282Y polymorphism and 19 publications including 21 case control studies, comprising 5,648 cases and 14,257 controls for HFE-H63D polymorphism were enrolled in our analysis. An increased risk for overall cancer risk was identified in HFE-H63D polymorphism under allele contrast (D vs H: OR=1.153; 95%CI=1.031- 1.289, Pheterogeneity=0.002), homozygotes vs wide type (DD vs HH: OR=1.449; 95%CI=1.182-1.777, Pheterogeneity=0.391), dominant model (DD+HD vs HH: OR=1.145; 95%CI=1.007-1.301, Pheterogeneity=0.002) and recessive model (DD vs HD+HH: OR=1.416 ; 95%CI=1.156-1.735, Pheterogeneity=0.549), as well as HFE- C282Y under homozygotes vs wide type (YY vs CC: OR=1.428, 95%CI=1.017-2.006, Pheterogeneity=0.220). In addition, in the stratified analysis by cancer type, an increased risk was identified in hepatocellular carcinoma and breast cancer in C282Y polymorphism, as well as pancreatic cancer in H63D polymorphism, whereas a decreased risk of colorectal cancer was identified in C282Y polymorphism. CONCLUSIONS: Present study suggested that H63D and C282Y polymorphisms associated with an increased risk of overall cancer. Nevertheless, well- designed study with large sample size will be continued on this issue of interest.
Piperno A, etal., Gastroenterology. 2000 Aug;119(2):441-5.
BACKGROUND & AIMS: Most hemochromatosis patients of Northern European descent are homozygous for the C282Y mutation of HFE gene. In Italy, many patients with iron overload are not homozygous for C282Y, and the presence of other mutations or other genetic determ
inant has been suggested. METHODS: Five unrelated Italian patients heterozygous for C282Y with the classic hemochromatosis phenotype were studied. The entire coding sequence and the exon-intron boundaries of the HFE gene were analyzed. Chromosome 6p haplotypes were defined in each patient by analysis of D6S265, D6S105, and D6S1281 microsatellites. RESULTS: Two novel nonsense HFE mutations were identified in exon 3 in the C282Y negative chromosome. The first one, a G-to-T transition at codon 168, was detected in 3 probands; the second, a G-to-A transition at codon 169, was detected in the others. CONCLUSIONS: The 2 nonsense mutations in the compound heterozygous state with C282Y result in the classic hemochromatosis phenotype in several unrelated Italian patients. This confirms that hemochromatosis in Italy is not as homogeneous as in northern Europe and suggests that other mutations can exist in C282Y or H63D heterozygotes with iron overload. These findings have practical implications for diagnostic and screening strategies for hemochromatosis.
BACKGROUND AND OBJECTIVE: Liver cirrhosis is the end-stage disease of chronic liver injury. Due to differences in the natural course of chronic liver diseases, identification of genetic factors that influence individual outcomes is warranted. HFE-link
ed hereditary hemochromatosis (HH) predisposes disease progression to cirrhosis; however, the role of heterozygous C282Y or H63D mutations in the development of cirrhosis in the presence of other etiological factors is still debated. The aim of this study was to determine the association between heterozygous C282Y and H63D mutations and non-HH liver cirrhosis in Lithuanian population. MATERIALS AND METHODS: The patient cohort consisted of 209 individuals. Diagnosis of cirrhosis was confirmed by clinical, laboratory parameters, liver biopsy, and radiological imaging. Control samples were obtained from 1005 randomly selected unrelated healthy individuals. HFE gene mutations were determined using the PCR-RFLP method. RESULTS: The most common causes of cirrhosis were hepatitis C (33.9%), hepatitis B (13.6%), and alcohol (25.8%). C282Y allele was associated with the presence of cirrhosis (OR=2.07; P=0.005); this was also observed under recessive model for C282Y (OR=2.06, P=0.008). The prevalence of C282Y allele was higher in cirrhotic men than in controls (7.0% vs. 2.8%, P=0.002). The carriage of H63D risk allele (OR=1.54; P=0.02), heterozygous C282Y/wt and homozygous H63D/H63D genotypes were associated with liver cirrhosis in males (OR=2.48, P=0.008, and OR=4.13, P=0.005, respectively). CONCLUSIONS: Heterozygous C282Y mutation of the HFE gene was associated with liver cirrhosis in the Lithuanian population. In gender-related analysis, heterozygous C282Y and homozygous H63D mutations were linked to liver cirrhosis in men, not in women.
Gnana-Prakasam JP, etal., Biochem J. 2009 Nov 11;424(2):243-52. doi: 10.1042/BJ20090424.
Haemochromatosis is an iron-overload disorder with age-dependent oxidative stress and dysfunction in a variety of tissues. Mutations in HFE (histocompatability leucocyte antigen class I-like protein involved in iron homoeostasis) are responsible for most cases o
f haemochromatosis. We demonstrated recently that HFE is expressed exclusively in the basal membrane of RPE (retinal pigment epithelium). In the present study, we used Hfe-/- mice to examine ferritin levels (an indirect readout for iron levels) and morphological changes in retina. We found increased ferritin accumulation in retina in 18-month-old, but not in 2-month-old, mice with considerable morphological damage compared with age-matched controls. The retinal phenotype included hypertrophy and hyperplasia of RPE. RPE cells isolated from Hfe-/- mice exhibited a hyperproliferative phenotype. We also compared the gene expression profile between wild-type and Hfe-/- RPE cells by microarray analysis. These studies showed that many cell cycle-related genes were differentially regulated in Hfe-/- RPE cells. One of the genes up-regulated in Hfe-/- RPE cells was Slc7a11 (where Slc is solute carrier) which codes for the 'transporter proper' xCT in the heterodimeric cystine/glutamate exchanger (xCT/4F2hc). This transporter plays a critical role in cellular glutathione status and cell-cycle progression. We confirmed the microarrray data by monitoring xCT mRNA levels by RT (reverse transcription)-PCR and also by measuring transport function. We also found increased levels of glutathione and the transcription factor/cell-cycle promoter AP1 (activator protein 1) in Hfe-/- RPE cells. Wild-type mouse RPE cells and human RPE cell lines, when loaded with iron by exposure to ferric ammonium citrate, showed increased expression and activity of xCT, reproducing the biochemical phenotype observed with Hfe-/- RPE cells.
Davis CF and Dorak MT, Ann Hematol. 2010 Apr;89(4):375-84. doi: 10.1007/s00277-009-0839-y. Epub 2009 Oct 6.
The most common mutation of the HFE gene C282Y has shown a risk association with childhood acute lymphoblastic leukemia (ALL) in Welsh and Scottish case-control studies. This finding has not been replicated outside Britain. Here, we present a thorough analysis
of the HFE gene in a panel of HLA homozygous reference cell lines and in the original population sample from South Wales (117 childhood ALL cases and 414 newborn controls). The 21 of 24 variants analyzed were from the HFE gene region extending 52 kb from the histone gene HIST1H1C to HIST1H1T. We identified the single-nucleotide polymorphism (SNP) rs807212 as a tagging SNP for the most common HFE region haplotype, which contains wild-type alleles of all HFE variants examined. This intergenic SNP rs807212 yielded a strong male-specific protective association (per allele OR = 0.38, 95% CI = 0.22-0.64, P (trend) = 0.0002; P = 0.48 in females), which accounted for the original C282Y risk association. In the HapMap project data, rs807212 was in strong linkage disequilibrium with 25 other SNPs spanning 151 kb around HFE. Minor alleles of these 26 SNPs characterized the most common haplotype for the HFE region, which lacked all disease-associated HFE variants. The HapMap data suggested positive selection in this region even in populations where the HFE C282Y mutation is absent. These results have implications for the sex-specific associations observed in this region and suggest the inclusion of rs807212 in future studies of the HFE gene and the extended HLA class I region.
There is interest in the role of iron in age-related diseases such as atherosclerosis. Tissue iron deposition could be harmful, because Fe(2+) can react with H(2)O(2) to form OH(-) radicals and Fe(2+) can react with O(2) to form reactive oxygen species. Free radicals react with cell membranes and ce
ll organelles and could lead to the development of atherosclerosis by initiating lipid peroxidation. Hereditary hemochromatosis provides an opportunity for studying the effects of iron on cardiovascular disease. Some studies have shown that individuals who carried HFE mutations may be at greater risk of developing coronary heart disease than those without the mutations. In contrast, a large number of studies have reported no association between HFE mutations and coronary heart disease. These studies have possible confounding factors, such as the homogeneity of the population in term of geographical origin among others. We studied the relation between HFE mutations and acute myocardial infarction in two case-control studies involving two sets of subjects representing different age groups from different geographic regions in Italy. The first one was composed of 172 older patients (139 males and 33 females; mean age 67) and 207 healthy controls (91 males and 116 females; mean age 46) from Emilia-Romagna. The second one was composed of younger 77 patients (75 males and 2 females; mean age 41) and 172 healthy controls (75 males and 97 females, mean age: 38) from Sicily. All patients were genotyped for ApoE alleles, since the ApoE- epsilon 4 allele is considered a risk factor for cardiovascular diseases and can interfere with other genetic and environmental factors by modifying susceptibility to this disease. DNA typing for C282Y and H63D HFE alleles was performed also. There were no significant differences in frequencies of the different HFE alleles between acute myocardial infarction patients and controls in cohorts of both old and young patients. Also taking into account the presence or absence of the ApoE- epsilon 4 allele, no significant differences in H63D allele frequencies were observed. Thus, our study, performed in two samples of genetically homogeneous patients and controls, does not support the suggestion that HFE mutations may be associated with acute myocardial infarction in susceptible individuals.
Iron overload is associated with acquired and genetic conditions, the most common being hereditary hemochromatosis (HH) type-I, caused by HFE mutations. Here, we conducted a hospital-based case-control study of 41 patients from the Sao Miguel Island (Azores, Po
rtugal), six belonging to a family with HH type-I pseudodominant inheritance, and 35 unrelated individuals fulfilling the biochemical criteria of iron overload compatible with HH type-I. For this purpose, we analyzed the most common HFE mutations- c.845G>A [p.Cys282Tyr], c.187C>G [p.His63Asp], and c.193A>T [p.Ser65Cys]. Results revealed that the family's HH pseudodominant pattern is due to consanguineous marriage of HFE-c.845G>A carriers, and to marriage with a genetically unrelated spouse that is a -c.187G carrier. Regarding unrelated patients, six were homozygous for c.845A, and three were c.845A/c.187G compound heterozygous. We then performed sequencing of HFE exons 2, 4, 5 and their intron-flanking regions. No other mutations were observed, but we identified the -c.340+4C [IVS2+4C] splice variant in 26 (74.3%) patients. Functionally, the c.340+4C may generate alternative splicing by HFE exon 2 skipping and consequently, a protein missing the alpha1-domain essential for HFE/ transferrin receptor-1 interactions. Finally, we investigated HFE mutations configuration with iron overload by determining haplotypes and genotypic profiles. Results evidenced that carriers of HFE-c.187G allele also carry -c.340+4C, suggesting in-cis configuration. This data is corroborated by the association analysis where carriers of the complex allele HFE-c.[187C>G;340+4T>C] have an increased iron overload risk (RR = 2.08, 95% CI = 1.40-2.94, p<0.001). Therefore, homozygous for this complex allele are at risk of having iron overload because they will produce two altered proteins--the p.63Asp [c.187G], and the protein lacking 88 amino acids encoded by exon 2. In summary, we provide evidence that the complex allele HFE-c.[187C>G;340+4T>C] has a role, as genetic predisposition factor, on iron overload in the Sao Miguel population. Independent replication studies in other populations are needed to confirm this association.
Sanchez M, etal., Gene 1998 Dec 28;225(1-2):77-87.
We have cloned and sequenced 1398bp of the rat HFE gene promoter region. The alignment of the rat promoter HFE sequence with the HFE promoter sequence from human and mouse detected sever
al highly conserved sequences present at orthologous or heterologous positions in the three species. Subsequent analysis of the conserved promoter sequences identified the presence of 10 novel transcription elements present in the promoter regions of the human, mouse and rat HFE genes (GATA, NF-IL6, AP1, AP2, CREB, PEA3, gamma-IRE, GFI1, HNF-3beta, HFH2). Different gel retardation analyses performed with rat-liver nuclear extracts have confirmed the presence of factors binding to some of these transcription elements. This represents the first data concerning the identification of potential transcriptional elements of the HFE promoter in these three species. The expression pattern of the transcription factors corresponding to the novel elements identified in the HFE promoter is consistent with the potential role of the HFE promoter in the transcription regulation and function of the HFE gene. Knowledge of the identified conserved elements in the HFE promoter from human, mouse and rat provides the basis for subsequent in-vitro or in-vivo studies leading to identification of the detailed mechanisms involved in the regulation of the iron metabolism and the design of potential future alternative therapies.
Eight hemochromatosis probands with HFE C282Y homozygosity had frequent, severe, or unusual infections and common variable immunodeficiency (CVID) or immunoglobulin (Ig) G subclass deficiency (IgGSD). Thus, we performed serum Ig isotyping and other characteriza
tion of 43 additional unselected probands, 5 human leukocyte antigen (HLA)-identical siblings, and 240 consecutive CVID or IgGSD index patients. C282Y allele frequencies were estimated in 58 CVID or IgGSD index patients without hemochromatosis phenotypes and in 341 controls. HLA-A and -B haplotypes and frequencies were determined in all 51 probands, 186 CVID or IgGSD index patients without hemochromatosis phenotypes, and 751 controls. Thirteen unselected probands (30%) had CVID or IgGSD. Among all 21 hemochromatosis probands with CVID (n = 4) or IgGSD (n = 17), Ig subclass deficiency patterns were IgG(1) (n = 5), IgG(1) and IgG(3) (n = 6), IgG(3) (n = 9), and IgG(1), IgG(3), and IgG(4) (n = 1). IgG(2) or IgA deficiency was not detected; one proband had IgM deficiency. Mean values of total IgG, IgG(1), and IgG(3) were significantly lower in probands with CVID or IgGSD. Mean values of age, transferrin saturation, and ferritin at diagnosis and phlebotomy units required to induce iron depletion were similar in probands with or without CVID or IgGSD; phlebotomy had no apparent effect on IgG levels. C282Y frequencies were similar in CVID or IgGSD index cases without hemochromatosis phenotypes and in controls. There was concordance of Ig and hemochromatosis phenotypes in probands and respective HLA-identical siblings. Eight of 240 CVID or IgGSD index patients had hemochromatosis phenotypes and C282Y homozygosity (3 vs 0.7% and 0.2% controls; P < 0.0001, respectively). The frequency of A*03-B*07 was greater in CVID and IgGSD index cases without hemochromatosis phenotypes than in controls (0.0968 vs 0.0546, respectively; P = 0.0032). HLA-A*03-B*07 was the predominant haplotype in probands grouped by presence or absence of CVID or IgGSD. Some probands in each group were A*03-B*07 homozygotes; group A*03-B*07 frequencies were similar. We conclude that serum IgG abnormalities characteristic of CVID or IgGSD are common in hemochromatosis probands, and that the prevalence of hemochromatosis is increased in CVID and IgGSD index cases. These observations could be explained by the increased frequencies of HLA-A*03-B*07 in C282Y homozygotes and in CVID and IgGSD, and by the common occurrence of putative CVID or IgGSD allele(s) on haplotypes bearing C282Y.
HFE is an MHC-related protein that is mutated in the iron-overload disease hereditary hemochromatosis. HFE binds to transferrin receptor (TfR) and reduces its affinity for iron-loaded transferrin, implicating HFE
nt-weight:700;'>HFE in iron metabolism. The 2.6 A crystal structure of HFE reveals the locations of hemochromatosis mutations and a patch of histidines that could be involved in pH-dependent interactions. We also demonstrate that soluble TfR and HFE bind tightly at the basic pH of the cell surface, but not at the acidic pH of intracellular vesicles. TfR:HFE stoichiometry (2:1) differs from TfR:transferrin stoichiometry (2:2), implying a different mode of binding for HFE and transferrin to TfR, consistent with our demonstration that HFE, transferrin, and TfR form a ternary complex.
Lee SM, etal., Genes Nutr. 2015 Jan;10(1):443. doi: 10.1007/s12263-014-0443-1. Epub 2014 Nov 27.
Hereditary hemochromatosis is an iron overload disorder most commonly caused by a defect in the HFE gene. While the genetic defect is highly prevalent, the majority of individuals do not develop clinically significant iron overload, suggesting the importance of
genetic modifiers. Murine hfe knockout models have demonstrated that strain background has a strong effect on the severity of iron loading. We noted that hepatic iron loading in hfe-/- mice occurs primarily over the first postnatal weeks (loading phase) followed by a timeframe of relatively static iron concentrations (plateau phase). We thus evaluated the effects of background strain and of age on hepatic gene expression in Hfe knockout mice (hfe-/-). Hepatic gene expression profiles were examined using cDNA microarrays in 4- and 8-week-old hfe-/- and wild-type mice on two different genetic backgrounds, C57BL/6J (C57) and AKR/J (AKR). Genes differentially regulated in all hfe-/- mice groups, compared with wild-type mice, including those involved in cell survival, stress and damage responses and lipid metabolism. AKR strain-specific changes in lipid metabolism genes and C57 strain-specific changes in cell adhesion and extracellular matrix protein genes were detected in hfe-/- mice. Mouse strain and age are each significantly associated with hepatic gene expression profiles in hfe-/- mice. These affects may underlie or reflect differences in iron loading in these mice.
The HFE gene encodes a protein involved in iron homeostasis; individuals with mutations in both alleles develop hemochromatosis. 27% of the French population is heterozygous for mutations in this gene. We found that 80% of the French athletes who won internation
al competitions in rowing, Nordic skiing and judo display mutations in one allele of HFE, thus demonstrating the existence of a favourable phenotype linked to this heterozygosity.
Possible association between the C282Y and H63D mutations in the HFE gene and estrogen-dependent cancer risk was assessed. Genotyping was performed using PCR amplification followed by digestion of products with specific restrictases. In a population of 260 heal
thy women (permanent residents of the southwest European Russia), mutant allele frequencies at the C282Y and H63D sites were evaluated as 3.3 and 16.3%, respectively. In patients with breast, ovarian, and endometrial cancer, C282Y frequencies were also low (1.0, 1.3, and 3.8%, respectively), and no cancer risk associated with the C282Y mutation was found. Odds ratios for breast cancer risk associated with the H63D mutation increased significantly with age: 0.5 in women below 48 years old, 1.0 in a range of 48-57 years, and 4.4 in older women (P(trend)=0.002). The latter value was statistically significant (95% CI, 1.4-14.1), indicating that women bearing the H63D mutation may be at an increased breast cancer risk at an age above 57 years. Preliminary results obtained in patients with two other estrogen-dependent malignancies revealed the same tendency to OR increase with age in ovarian cancer patients (P(trend)=0.008), but no age-related OR differences in endometrial cancer patients.
Pedersen P and Milman N, Ann Hematol. 2009 Aug;88(8):775-84. doi: 10.1007/s00277-008-0679-1. Epub 2009 Jan 22.
The aim of this epidemiologic population survey was to assess the penetrance of the most frequent hemochromatosis (HFE) gene variants in ethnic Danish men. A cohort of 6,020 men aged 30-53 years was screened for HFE C282Y, H
63D, and S65C variants by restriction fragment length polymorphism analysis. Subsequently, iron status markers (serum transferrin saturation, serum ferritin) were analyzed in 1,452 men. The C282Y allele was present in 5.6%, H63D in 12.8%, and S65C in 1.8% of the men. We found 23 out of 6,020 (0.38%) C282Y homozygotes, of whom two had been treated with phlebotomy. Among untreated C282Y homozygotes (n = 21) with available iron status markers (transferrin saturation n = 18, ferritin n = 16), 89% had elevated transferrin saturation >or=50%, 94% had elevated ferritin >or=300 microg/L, and 88% had elevation of both iron status markers; seven out of 16 (44%) had ferritin values >800 microg/L. One C282Y homozygote had normal iron status markers possibly due to nonexpressivity. Among C282Y/H63D compound heterozygotes (n = 66), 23% had elevated transferrin saturation, 27% elevated ferritin, and 9% elevation of both iron status markers. Among H63D/H63D homozygotes (n = 74), 15% had elevated transferrin saturation, 19% elevated ferritin, and 5.4% elevation of both iron status markers. Among C282Y/wild type (wt) heterozygotes (n = 255), 9% had elevated transferrin saturation, 9% elevated ferritin, and 1.2% elevation of both iron status markers. Among H63D/wt heterozygotes (n = 600), 8% had elevated transferrin saturation, 12% elevated ferritin, and 2% elevation of both iron status markers. None of the men with the S65C variant displayed elevation of both iron status markers. In conclusion, this study demonstrates a high penetrance of the C282Y variant in Danish men followed by the H63D variant while the S65D variant had no significant impact on iron status markers.
H63D HFE is associated with iron dyshomeostasis and oxidative stress; each of which plays an important role in amyotrophic lateral sclerosis (ALS) pathogenesis. To examine the role of H63D HFE in ALS, we generated a double t
ransgenic mouse line (SOD1/H67D) carrying the H67D HFE (homologue of human H63D) and SOD1(G93A) mutations. We found double transgenic mice have shorter survival and accelerated disease progression. We examined parameters in the lumbar spinal cord of double transgenic mice at 90days (presymptomatic), 110days (symptomatic) and end-stage. Transferrin receptor and L-ferritin expression, both indicators of iron status, were altered in double transgenic and SOD1 mice starting at 90days, indicating loss of iron homeostasis in these mice. However, double transgenic mice had higher L-ferritin expression than SOD1 mice. Double transgenic mice exhibited increased Iba-1 immunoreactivity and caspase-3 levels, indicating increased microglial activation which would be consistent with the higher L-ferritin levels. Although both SOD1 and double transgenic mice had increased GFAP expression, the magnitude of the increase was higher in double transgenic mice at 110days, suggesting increased gliosis in these mice. Increased hemeoxygenase-1 and decreased nuclear factor E2-related factor 2 levels in double transgenic mice strongly suggest the accelerated disease process could be associated with increased oxidative stress. There was no evidence of TAR-DNA-binding protein 43 mislocalization to the cytoplasm in double transgenic mice; however, there was evidence suggesting neurofilament disruption, which has been reported in ALS. Our findings indicate H63D HFE modifies ALS pathophysiology via pathways involving oxidative stress, gliosis and disruption of cellular functions.
Heterozygous mutations of the Hfe gene have been proposed as cofactors in the development and progression of nonalcoholic fatty liver disease (NAFLD). Homozygous Hfe deletion previously has been shown to lead to dysregulated
hepatic lipid metabolism and accentuated liver injury in a dietary mouse model of NAFLD We sought to establish whether heterozygous deletion of Hfe is sufficient to promote liver injury when mice are exposed to a high-calorie diet (HCD). Eight-week-old wild-type and Hfe(+/-) mice received 8 weeks of a control diet or HCD Liver histology and pathways of lipid and iron metabolism were analyzed. Liver histology demonstrated that mice fed a HCD had increased NAFLD activity score (NAS), steatosis, and hepatocyte ballooning. However, liver injury was unaffected by Hfe genotype. Hepatic iron concentration (HIC) was increased in Hfe(+/-) mice of both dietary groups. HCD resulted in a hepcidin-independent reduction in HIC Hfe(+/-) mice demonstrated raised fasting serum glucose concentrations and HOMA-IR score, despite unaltered serum adiponectin concentrations. Downstream regulators of hepatic de novo lipogenesis (pAKT, SREBP-1, Fas, Scd1) and fatty acid oxidation (AdipoR2, Pparalpha, Cpt1) were largely unaffected by genotype. In summary, heterozygous Hfe gene deletion is associated with impaired iron and glucose metabolism. However, unlike homozygous Hfe deletion, heterozygous gene deletion did not affect lipid metabolism pathways or liver injury in this model.
Andrikovics H, etal., Cancer Epidemiol Biomarkers Prev. 2009 Mar;18(3):929-34. doi: 10.1158/1055-9965.EPI-08-0359. Epub 2009 Mar 3.
Iron metabolism has been implicated in carcinogenesis and several studies assessed the potential role of genetic variants of proteins involved in iron metabolism (HFE C282Y, TFR S142G) in different malignancies. Few reports addressed this issue with relation to
chronic myeloproliferative disorders (CMPD). The aims of our study were (a) to examine the potential associations of CMPD development with genetic modifiers of iron metabolism in a large cohort of CMPD patients; (b) to examine associations of genetic variants of proteins involved in iron metabolism; and acquired JAK2 V617F mutation with clinical characteristics of CMPD. HFE C282Y was genotyped in 328 CMPD patients and 996 blood donors as controls, HFE H63D, and TFR S142G were tested in CMPD patients and 171 first time blood donors. JAK2 V617F mutation was tested in CMPD patients and in 122 repeated blood donors. Decreased C282Y allele frequency (allele frequency+/-95% confidence interval) was found in the CMPD group (1.8%+/-1.0%) compared with controls (3.4%+/-0.8%; P=0.048). TFR S142G allele frequency was reduced among V617F-negative CMPD patients (34.8%+/-7.6%) compared with controls (47.8%+/-5.4%; P=0.02). The frequency of JAK2 V617F was 75.9% (249 of 328) in the CMPD group. At presentation, elevated hemoglobin levels were found in V617F-positive patients compared with V617F-negative counterparts (P<0.000). Vascular complications (26.6% versus 15.2%; P=0.039) as well as female gender (57.4% versus 41.8%; P=0.019) were more common in V617F-positive patients. We found that HFE C282Y might be associated with a protective role against CMPD. Because chronic iron deficiency or latent anemia may trigger disease susceptibility for CMPD, HFE C282Y positivity may be a genetic factor influencing this effect.
Hereditary hemochromatosis (HH) is a common autosomal recessive genetic disorder of iron metabolism. The HFE candidate gene encoding an HLA class I-like protein involved in HH was identified in 1996. Two missense mutations have been described: C282Y, accounting
for 80% to 90% of HH chromosomes, and H63D, which is associated with a milder form of the disease representing 40% to 70% of non-C282Y HH chromosomes. We report here on the analysis of C282Y, H63D, and the 193A-->T substitution leading to the S65C missense substitution in a large series of probands and controls. The results confirm that the C282Y substitution was the main mutation involved in hemochromatosis, accounting for 85% of carrier chromosomes, whereas the H63D substitution represented 39% of the HH chromosomes that did not carry the C282Y mutation. In addition, our screening showed that the S65C substitution was significantly enriched in probands with at least one chromosome without an assigned mutation. This substitution accounted for 7.8% of HH chromosomes that were neither C282Y nor H63D. This enrichment of S65C among HH chromosomes suggests that the S65C substitution is associated with the mild form of hemochromatosis.
Identification of choriocarcinoma within a germ cell tumor can have major implications for the subsequent staging and treatment of testicular neoplasms. Immunoperoxidase staining greatly enhances the speed and sensitivity of identifying occult, though clinically significant, tumor components. In mix
ed germ cell tumors, staining for beta-human chorionic gonadotropin (ß-hCG) has been historically used to assess for the presence and burden of choriocarcinoma. However, current ß-hCG stains produce variable, intense staining of trophoblastic elements and surrounding tissues, clouding the assessment of true-positive staining. Human hemochromatosis protein (HFE) is a membrane bound mediator of iron transport expressed at high levels within placenta. Additionally, previous reports have demonstrated that choriocarcinoma cell lines express HFE, although in vivo expression had not been examined. To address whether HFE can stain trophoblastic elements, HFE immunohistochemistry was conducted in choriocarcinoma (n = 4), mixed germ cell tumors (n = 11), seminoma (n = 4), and placenta (n = 11). HFE consistently demonstrated cytoplasmic and membranous staining, highlighting both syncytiotrophoblasts and cytotrophoblasts within choriocarcinoma and placenta. Staining of intratumoral white blood cells was observed within seminomas and mixed germ cell tumors, corroborating prior reports stating that HFE highlights monocytes and macrophages. Taken together, HFE may serve as an alternative target from ß-hCG for immunoperoxidase studies when highlighting choriocarcinoma.
A number of previous studies have demonstrated that the HFE H63D polymorphism is associated with increased risk of incidence multiple types of cancer, including colorectal cancer, breast cancer, liver cancer, pancreatic cancer, and gynecological malignant tumor
s. However, the clinical outcomes were inconsistent. Therefore, this meta-analysis was conducted to summarize the effect of the H63D variant on the incidence of solid tumor. PubMed and EMBASE databases were searched for articles associating the HFE H63D polymorphism with cancer risk. The relationships were evaluated by calculating the pooled odds ratios (ORs) with 95% confidence intervals (CIs). A total of 28 studies, including 7728 cancer cases and 11,895 controls, were identified. Statistically significant associations were identified between the HFE H63D polymorphism and solid cancer risk (CG vs CC, OR = 1.14, 95%CI = 1.07-1.23, P < 0.001; GG vs CC, OR = 1.28, 95%CI = 1.06-1.55, P = 0.010; CG/GG vs CC, OR = 1.16, 95%CI = 1.08-1.24, P < 0.001; GG vs CC/CG, OR = 1.24, 95%CI = 1.02-1.49, P = 0.027). In the subgroup analysis, we illustrated the effect of the H63D polymorphism on hepatocellular carcinoma and pancreatic cancer risk, particularly in the Asian and African subgroups; however, this was not observed in gynecological malignant tumors. In summary, this analysis provided strong evidence that the HFE H63D polymorphism may play a critical role in the increased aggressiveness of hepatocellular carcinoma and pancreatic cancer.
Zhang AS, etal., Blood 2004 Feb 15;103(4):1509-14. Epub 2003 Oct 16.
The mRNAs of proteins involved in iron metabolism were measured in isolated hepatocytes, Kupffer cells, sinusoidal endothelial cells (SECs), and hepatic stellate cells (HSCs). Levels of type I hereditary hemochromatosis gene (HFE), transferrin, hepcidin, transfe
rrin receptors 1 and 2 (TfR1, TfR2), ferroportin 1 (FPN1), divalent metal transporter 1 (DMT1), natural resistance-associated macrophage protein 1 (Nramp1), ceruloplasmin, hephaestin, and glyceraldehyde 3-phosphate dehydrogenase (GAPDH), were measured by quantitative reverse-transriptase polyerase chain reaction (qRT-PCR). We show that hepatocytes express almost all the iron-related genes tested, in keeping with their central role in iron metabolism. In addition, hepatocytes had 10-fold lower TfR1 mRNA levels than TfR2 and the lowest levels of TfR1 of the 4 cell types isolated. Kupffer cells, which process senescent red blood cells and recycle the iron, had high levels of ferroportin 1, ceruloplasmin, and hephaestin mRNA. Most important, of all the cell types tested, hepatocytes had the highest level of HFE mRNA, a factor of 10 higher than Kupffer cells. In situ hybridization analysis was conducted with rat liver sections. Consistent with the qRT-PCR analysis, HFE gene expression was localized mainly in hepatocytes. Western blot analysis confirmed this finding. Unexpectedly, HSCs also had high levels of DMT1 and ferroportin, implicating them in either iron sensing or iron cycling.
Lebeau A, etal., Eur J Clin Invest. 2002 Aug;32(8):603-12.
BACKGROUND: HFE knockout mice (C57BL/6 x 129/Ola strain) mimic the functional aberrations of human hereditary haemochromatosis (HH) in short-term experiments. The present study investigates functional and morphological long-term changes. METHODS: HFE
ont-weight:700;'>HFE(o/o), HFE(+/o) and HFE(+/+) mice were maintained on iron-rich and control diets for 2 weeks, 3, 12 and 18 months. Light microscopic tissue iron distribution, pathomorphological alterations, tissue iron content and oxidative stress were analysed in liver, pancreas, spleen, gastrointestinal tract, kidneys and myocardium. Additionally, duodenal 59Fe absorption and 59Fe whole body loss were measured. RESULTS: Iron distribution between organs and microscopic iron deposition in the tissues resembled the patterns described in HH. After 3 months of iron-rich feeding duodenal 59Fe absorption decreased to approximately 15% of iron-adequate controls but remained about twice as high in HFE(o/o) as in HFE(+/+) mice. Hepatic iron concentrations reached only half the values known to induce hepatic fibrosis in rats and humans, while whole body 59Fe loss was about twice as high. Consequently no hepatic fibrosis developed, although massive hepatocellular iron deposition and indication for oxidative stress were observed. CONCLUSION: C57BL/6 x 129/O1a HFE(o/o) mice mimic HH iron distribution and the regulation of intestinal iron absorption after long-term feeding. However, characteristic morphological late changes in untreated HH are not modelled.
Costa M, etal., PLoS One. 2015 Apr 16;10(4):e0124246. doi: 10.1371/journal.pone.0124246. eCollection 2015.
Abnormally low CD8+ T-lymphocyte numbers is characteristic of some patients with hereditary hemochromatosis (HH), a MHC-linked disorder of iron overload. Both environmental and genetic components are known to influence CD8+ T-lymphocyte homeostasis but the role of the HH associated protein HFE
yle='font-weight:700;'>HFE is still insufficiently understood. Genome-wide expression profiling was performed in peripheral blood CD8+ T lymphocytes from HH patients selected according to CD8+ T-lymphocyte numbers and from Hfe-/- mice maintained either under normal or high iron diet conditions. In addition, T-lymphocyte apoptosis and cell cycle progression were analyzed by flow cytometry in HH patients. HH patients with low CD8+ T-lymphocyte numbers show a differential expression of genes related to lymphocyte differentiation and maturation namely CCR7, LEF1, ACTN1, NAA50, P2RY8 and FOSL2, whose expression correlates with the relative proportions of naive, central and effector memory subsets. In addition, expression levels of LEF1 and P2RY8 in memory cells as well as the proportions of CD8+ T cells in G2/M cell cycle phase are significantly different in HH patients compared to controls. Hfe-/- mice do not show alterations in CD8+ T-lymphocyte numbers but differential gene response patterns. We found an increased expression of S100a8 and S100a9 that is most pronounced in high iron diet conditions. Similarly, CD8+ T lymphocytes from HH patients display higher S100a9 expression both at the mRNA and protein level. Altogether, our results support a role for HFE as a negative regulator of CD8+ T-lymphocyte activation. While the activation markers S100a8 and S100a9 are strongly increased in CD8+ T cells from both, Hfe-/- mice and HH patients, a differential profile of genes related to differentiation/maturation of CD8+ T memory cells is evident in HH patients only. This supports the notion that HFE contributes, at least in part, to the generation of low peripheral blood CD8+ T lymphocytes in HH.
PURPOSE: To evaluate the frequency of mutations in the HFE gene (C282Y and H63D) in type 2 diabetes mellitus (DM) patients and their possible association with diabetic chronic complications. METHODS: A case-control study with 723 subjects was performed. All dia
betic subjects (n=519) underwent a clinical and laboratory evaluation. Diabetic retinopathy (DR) was evaluated by an ophthalmologist. Diabetic nephropathy (DN) was categorized by urinary albumin excretion (UAE) as normoalbuminuria (n=247), microalbuminuria (n=68), macroalbuminuria (n=70), or the presence of end-stage renal disease (dialysis; n=134). Data available for blood donors (n=204) were limited to age, sex, body mass index, and absence of previous diagnosis of diabetes and normal fasting plasma glucose. The mutations C282Y and H63D in the HFE gene were genotyped based on PCR protocols and digested with the restriction enzymes SnabI (C282Y) and MboI (H63D). RESULTS: There was an association of type 2 DM with H63D polymorphism (genotypes HD/DD: OR=1.7, 95% CI=1.2-2.6), but not with C282Y polymorphism (OR=0.7, 955 CI=0.4-1.4). In respect to the chronic complications, there was no difference in the prevalence of DR, DN, or ischemic heart disease among the different genotypes. CONCLUSIONS: Mutation H63D in the HFE gene was associated with a higher risk of type 2 DM, but did not appear to confer risk for diabetic chronic complications. The mutation C282Y was not associated with diabetes or its chronic complications.
Smith DJ, etal., Gene. 2019 Jan 30;683:12-17. doi: 10.1016/j.gene.2018.10.002. Epub 2018 Oct 3.
BACKGROUND AND OBJECTIVE: Genetic modifiers contribute to variable disease phenotype in cystic fibrosis (CF). We explored the association between mutations in the hemochromatosis (HFE) gene and disease severity in adults with CF. METHODS: ... (more)
pan style='font-weight:700;'>HFE genotyping was performed in 163 adults with CF attending a single centre. Results were correlated with lung disease severity, prevalence of CF-related diabetes (CFRD) and history of meconium ileus (MI) or distal intestinal obstruction syndrome (DIOS). RESULTS: Subjects with the C282Y substitution in the HFE protein (C282Y mutation) had a lower FEV1 percentage predicted (54% versus 66%, p = 0.029) and accelerated rate of FEV1 decline (-110 mL versus -80 mL per year respectively, p < 0.001) compared to subjects with a normal HFE genotype. C282Y substitutions were associated with increased rates of CFRD (58% versus 33%, p = 0.026) and a trend towards increased MI or DIOS (38% versus 19%, p = 0.05). H63D HFE substitutions were associated with a more rapid rate of decline in forced vital capacity (p = 0.01) and increased risk of MI or DIOS (p = 0.02). CONCLUSIONS: In subjects with CF, the C282Y HFE substitution was associated with worse lung function, and increased rates of CFRD and gastrointestinal complications. The H63D HFE substitution also impacted on disease phenotype, but to a lesser extent. The results support a role for HFE gene mutations as modifiers of CF phenotype.
BACKGROUND: Hemochromatosis gene (HFE) mutations and the hepatitis C virus (HCV) are known risk factors for porphyria cutanea tarda (PCT), but interactions with erythrocytic uroporphyrinogen decarboxylase (UROD) have seldom been addressed. OBJECTIVE: In order t
o examine the links between these factors, we conducted a multicentre prospective case-control study. METHODS: PCT patients with (n = 32) or without HCV (n = 28) were matched to HCV+ (n = 32) and HCV- controls (n = 28). HFE mutations (C282Y and H63D) were analyzed by PCR. RESULTS: PCT+/HCV+ patients were younger than PCT+/HCV- patients (46.9 vs. 58.2 years, p < 0.001). UROD values were not significantly different in HCV+ and HCV- patients. Both C282Y and H63D were more frequent in PCT+ patients than in controls, but there was no difference in HFE genotype according to HCV seropositivity. Mean UROD was lower in case of HFE mutations in both PCT patients and controls. CONCLUSION: In French patients, HCV infection is probably the major causal factor of PCT. It is not linked with HFE mutations, although they are significantly associated with PCT. A low erythrocytic UROD might be a predisposing factor. The UROD value was lower in patients with HFE mutations, suggesting a possible interaction between HFE genotype and UROD levels.
Robson KJ, etal., J Med Genet 2004 Apr;41(4):261-5.
BACKGROUND: There is evidence that iron may play a role in the pathology of Alzheimer's disease (AD). There may be genetic factors that contribute to iron deposition resulting in tissue damage thus exacerbating AD. METHODS: We have genotyped 269 healthy elderly controls, 191 cases with definite or p
robable AD, and 69 with mild cognitive impairment (MCI) from the OPTIMA cohort. RESULTS: We have examined the interaction between the C2 variant of the transferrin (TF) gene and the C282Y allele of the haemochromatosis (HFE) gene as risk factors for developing AD. Our results showed that each of the two variants was associated with an increased risk of AD only in the presence of the other. Neither allele alone had any effect. Carriers of both variants were at 5 times greater risk of AD compared with all others. The interaction was significant by logistic regression (p = 0.014) and by synergy factor analysis (p = 0.015, synergy factor = 5.1). Further, carriers of these two alleles plus apolipoprotein E epsilon4 (APOE4) were at still higher risk of AD: of the 14 tri-carriers of the three variants, identified in this study, 12 had AD and two MCI. CONCLUSION: We suggest that the combination of TF C2 and HFE C282Y may lead to an excess of redox-active iron and the induction of oxidative stress in neurones, which is exacerbated in carriers of APOE4. Since 4% of Northern Europeans carry the two iron-related variants and since iron overload is a treatable condition, these results merit replication.
Tsui WM, etal., Hong Kong Med J. 2000 Jun;6(2):153-8.
OBJECTIVE: To detect two novel mutations (C282Y and H63D) of the HFE gene in Chinese patients with hepatic iron overload. DESIGN: Multicentre retrospective study. SETTING: Four public hospitals, Hong Kong. PARTICIPANTS: Fifty Chinese patients who presented from
January 1987 through December 1999 with hepatic iron overload from various causes. MAIN OUTCOME MEASURES: The DNA from liver biopsy samples was tested for HFE mutations by restriction fragment length polymorphism analysis. RESULTS: The sample DNA quality was unsatisfactory for analysis of the C282Y mutation in one case and the H63D mutation in nine cases. The C282Y mutation was not detected in any of the 49 satisfactory samples. Three of the 41 samples were heterozygous for the H63D mutation and only one was homozygous, giving an allele frequency of 6.1%. Of the three H63D-heterozygotes, one had beta-thalassaemia major, one had beta-thalassaemia minor, and one had hereditary spherocytosis. None of the 12 patients who were presumed to have primary haemochromatosis were positive for either mutation. CONCLUSIONS: The classical form of human leukocyte antigen-linked hereditary haemochromatosis appears to be absent form this locality. The H63D mutation is found in a minority (9.8%) of the patients, in whom it may act synergistically with an erythropoietic factor.
Roy CN, etal., J Biol Chem 1999 Mar 26;274(13):9022-8.
HFE is the protein product of the gene mutated in the autosomal recessive disease hereditary hemochromatosis (Feder, J. N., Gnirke, A., Thomas, W., Tsuchihashi, Z., Ruddy, D. A., Basava, A., Dormishian, F., Domingo, R. J., Ellis, M. C., Fullan, A., Hinton, L. M.
, Jones, N. L., Kimmel, B. E., Kronmal, G. S., Lauer, P., Lee, V. K., Loeb, D. B., Mapa, F. A., McClelland, E., Meyer, N. C., Mintier, G. A., Moeller, N., Moore, T., Morikang, E., Prasss, C. E., Quintana, L., Starnes, S. M., Schatzman, R. C., Brunke, K. J., Drayna, D. T., Risch, N. J., Bacon, B. R., and Wolff, R. R. (1996) Nat. Genet. 13, 399-408). At the cell surface, HFE complexes with transferrin receptor (TfR), increasing the dissociation constant of transferrin (Tf) for its receptor 10-fold (Gross, C. N., Irrinki, A., Feder, J. N., and Enns, C. A. (1998) J. Biol. Chem. 273, 22068-22074; Feder, J. N., Penny, D. M., Irrinki, A., Lee, V. K., Lebron, J. A., Watson, N. , Tsuchihashi, Z., Sigal, E., Bjorkman, P. J., and Schatzman, R. C. (1998) Proc. Natl. Acad. Sci. U S A 95, 1472-1477). HFE does not remain at the cell surface, but traffics with TfR to Tf-positive internal compartments (Gross et al., 1998). Using a HeLa cell line in which the expression of HFE is controlled by tetracycline, we show that the expression of HFE reduces 55Fe uptake from Tf by 33% but does not affect the endocytic or exocytic rates of TfR cycling. Therefore, HFE appears to reduce cellular acquisition of iron from Tf within endocytic compartments. HFE specifically reduces iron uptake from Tf, as non-Tf-mediated iron uptake from Fe-nitrilotriacetic acid is not altered. These results explain the decreased ferritin levels seen in our HeLa cell system and demonstrate the specific control of HFE over the Tf-mediated pathway of iron uptake. These results also have implications for the understanding of cellular iron homeostasis in organs such as the liver, pancreas, heart, and spleen that are iron loaded in hereditary hemochromatotic individuals lacking functional HFE.
We initiated the present work to determine whether the presence of the HFE C282Y or H63D mutations could be related to the clinical expression of diabetes mellitus type 2. Two hundred and twenty five type 2 consecutive diabetic patients were included and the ... (more)
pan style='font-weight:700;'>HFE genotypes were determined. Younger ages of onset of diabetes as well as a longer duration of the disease were detected in patients carrying at least one C282Y allele (p = 0.007). An increased prevalence of retinopathy (p = 0.014) and of nephropathy (p = 0.04) were also detected in individuals carrying at least one C282Y allele in comparison with patients carrying the other alleles. The increased prevalence of retinopathy in C282Y carriers is related to the increased duration of the disease, but we not have detected that the prevalence of nephropathy is associated with the duration of the disease. However, multivariate logistic regression confirms that the prevalence of nephropathy is higher in the group of patients carrying at least one C282Y allele or the H63D/H63D genotype as compared to the group of patients with the wild-type (N/N) or the N/H63D genotype. To our knowledge our study is the first one to report an earlier age of onset in type 2 diabetic patients carrying HFE mutations.
Beiranvand E, etal., Recent Adv DNA Gene Seq. 2015;9(1):58-64.
The role of HFE gene mutations or its expression in regulation of iron metabolism of hereditary haemochromatosis (HH) patients is remained controversial. Therefore here the correlation between two common HFE genotype (p.C282
Y, p.H63D) and HFE gene expression with iron status in HH, iron deficiency anemia (IDA) and healthy Iranian participants was studied. For this purpose genotype determination was done by polymerase chain reaction--restriction fragment length polymorphism (PCR-RFLP). Real-Time PCR was applied for evaluation of HFE gene expression. Biochemical parameters and iron consumption were also assessed. Homozygote p.H63D mutation was seen in all HH patients and p.C282Y was not observed in any member of the population. A significant correlation was observed between serum ferritin (SF) level and gender or age of HH patients. p.H63D homozygote was seen to be able to significantly increase SF and transferrin saturation (TS) level without affecting on liver function. Our results also showed that iron consumption affects on TS level increasing. HFE gene expression level of IDA patients was significantly higher than other groups. Also the HFE gene expression was negatively correlated with TS. Finally, the main result of our study showed that loss of HFE function in HH is not derived from its gene expression inhibition and much higher HFE gene expression might lead to IDA. However we propose repeating of the study for more approval of our finding.
Tumor necrosis factor α inhibitors (anti-TNF) have improved treatment of several complex diseases, including Crohn's disease (CD). However, the effect varies and approximately one-third of the patients do not respond. Since blood parameters as well as genetic factors have shown a great potenti
al to predict response during treatment, the aim of the study was to evaluate response to anti-TNF treatment with adalimumab (ADA) between genes HFE and TF and haematological parameters in Slovenian refractory CD patients. Single nucleotide polymorphisms (SNPs) rs1799852 in gene TF and rs2071303 in gene HFE were genotyped in 68 refractory CD patients for which response has been measured using inflammatory bowel disease questionnaire (IBDQ) index. Haematological parameters and IBDQ index were determined before therapy and after 4, 12, 20 and 30 weeks. We found novel strong association between SNP rs2071303 in gene HFE and response to ADA treatment, particularly patients with G allele comparing to A allele had better response after 20 weeks (p = 0.008). Further, we found strong association between transferrin level at baseline and treatment response after 12, 20 and 30 weeks, where average transferrin level before therapy was lower in responders (2.38 g/L) compared to non-responders (2.89 g/L, p = 0.005). Association was found between transferrin level in week 30 and SNP rs1799852 (p = 0.023), and between MCHC level before treatment and SNP rs2071303 (p = 0.007). Our results suggest that SNP in gene HFE as well as haematological markers serve as promising prognostic markers of response to anti-TNF treatment in CD patients.
Mattman A, etal., Blood. 2002 Aug 1;100(3):1075-7. doi: 10.1182/blood-2002-01-0133.
Hereditary hemochromatosis (HH) is classically associated with a Cys282Tyr (C282Y) mutation of the HFE gene. Non-C282Y HH is a heterogeneous group accounting for 15% of HH in Northern Europe. Pathogenic mutations of the transferrin receptor 2 (TfR2) gene have be
en identified in 4 Italian pedigrees with the latter syndrome. The goal of this study was to perform a mutational analysis of the TfR2 and HFE genes in a cohort of non-C282Y iron overload patients of mixed ethnic backgrounds. Several sequence variants were identified within the TfR2 gene, including a homozygous missense change in exon 17, c2069 A-->C, which changes a glutamine to a proline residue at position 690. This putative mutation was found in a severely affected Portuguese man and 2 family members with the same genotype. In summary, pathologic TfR2 mutations are present outside of Italy, accounting for a small proportion of non-C282Y HH.
Juvenile hemochromatosis is an early-onset autosomal recessive disorder of iron overload resulting in cardiomyopathy, diabetes and hypogonadism that presents in the teens and early 20s (refs. 1,2). Juvenile hemochromatosis has previously been linked to the centromeric region of chromosome 1q (refs.
3-6), a region that is incomplete in the human genome assembly. Here we report the positional cloning of the locus associated with juvenile hemochromatosis and the identification of a new gene crucial to iron metabolism. We finely mapped the recombinant interval in families of Greek descent and identified multiple deleterious mutations in a transcription unit of previously unknown function (LOC148738), now called HFE2, whose protein product we call hemojuvelin. Analysis of Greek, Canadian and French families indicated that one mutation, the amino acid substitution G320V, was observed in all three populations and accounted for two-thirds of the mutations found. HFE2 transcript expression was restricted to liver, heart and skeletal muscle, similar to that of hepcidin, a key protein implicated in iron metabolism. Urinary hepcidin levels were depressed in individuals with juvenile hemochromatosis, suggesting that hemojuvelin is probably not the hepcidin receptor. Rather, HFE2 seems to modulate hepcidin expression.
Kim DH, etal., J Microbiol Biotechnol. 2015 Oct;25(10):1768-71. doi: 10.4014/jmb.1503.03092.
Human Fen1 protein (hFen1) plays an important role in Okazaki fragment processing by cleaving the flap structure at the junction between single-stranded (ss) DNA and doublestranded (ds) DNA, an intermediate formed during Okazaki fragment processing, resulting in ligatable nicked dsDNA. It was report
ed that hChlR1, a member of the cohesion establishment factor family, stimulates hFen1 nuclease activity regardless of its ATPase activity. In this study, we found that cohesion establishment factors cooperatively stimulate endonuclease activity of hFen1 in in vivo mimic condition, including replication protein-A-coated DNA and high salt. Our findings are helpful to explain how a DNA replication machinery larger than the cohesion complex goes through the cohesin ring structure on DNA during S phase in the cell cycle.
Tan KM, etal., J Biol Chem. 2001 Nov 23;276(47):44193-202. Epub 2001 Sep 14.
In Caenorhabditis elegans, fem-1, fem-2, and fem-3 play pivotal roles in sex determination. Recently, a mammalian homologue of the C. elegans sex-determining protein FEM-1, F1Aalpha, has been described. Although there is little evidence to link F1Aalpha to sex determination, F1Aalpha and FEM-1 both
promote apoptosis in mammalian cells. Here we report the identification and characterization of a human homologue of the C. elegans sex-determining protein FEM-2, hFEM-2. Similar to FEM-2, hFEM-2 exhibited PP2C phosphatase activity and associated with FEM-3. hFEM-2 shows striking similarity (79% amino acid identity) to rat Ca(2+)/calmodulin (CaM)-dependent protein kinase phosphatase (rCaMKPase). hFEM-2 and FEM-2, but not PP2Calpha, were demonstrated to dephosphorylate CaM kinase II efficiently in vitro, suggesting that hFEM-2 and FEM-2 are specific phosphatases for CaM kinase. Furthermore, hFEM-2 and FEM-2 associated with F1Aalpha and FEM-1 respectively. Overexpression of hFEM-2, FEM-2, or rCaMKPase all mediated apoptosis in mammalian cells. The catalytically active, but not the inactive, forms of hFEM-2 induced caspase-dependent apoptosis, which was blocked by Bcl-XL or a dominant negative mutant of caspase-9. Taken together, our data suggest that hFEM-2 and rCaMKPase are mammalian homologues of FEM-2 and they are evolutionarily conserved CaM kinase phosphatases that may have a role in apoptosis signaling.
