| 11527035 | Correction of Hair Shaft Defects through Allele-Specific Silencing of Mutant Krt75. | Liu Y, etal., J Invest Dermatol. 2016 Jan;136(1):45-51. doi: 10.1038/JID.2015.375. | Dominant mutations in keratin genes can cause a number of inheritable skin disorders characterized by intraepidermal blistering, epidermal hyperkeratosis, or abnormalities in skin appendages, such as nail plate dystrophy and structural defects in hair. Allele-specific silencing of mutant keratins t hrough RNA interference is a promising therapeutic approach for suppressing the expression of mutant keratins and related phenotypes in the epidermis. However, its effectiveness on skin appendages remains to be confirmed in vivo. In this study, we developed allele-specific small interfering RNAs capable of selectively suppressing the expression of a mutant Krt75, which causes hair shaft structural defects characterized by the development of blebs along the hair shaft in mice. Hair regenerated from epidermal keratinocyte progenitor cells isolated from mutant Krt75 mouse models reproduced the blebbing phenotype when grafted in vivo. In contrast, mutant cells manipulated with a lentiviral vector expressing mutant Krt75-specific short hairpin RNA (shRNA) persistently suppressed this phenotype. The phenotypic correction was associated with a significant reduction of mutant Krt75 mRNA in the skin grafts. Thus, data obtained from this study demonstrated the feasibility of utilizing RNA interference to achieve durable correction of hair structural phenotypes through allele-specific silencing of mutant keratin genes. | 26763422 | 2016-08-01 |
| 598118121 | Autosomal recessive transmission of a rare KRT74 variant causes hair and nail ectodermal dysplasia: allelism with dominant woolly hair/hypotrichosis. | Raykova D, etal., PLoS One. 2014 Apr 8;9(4):e93607. doi: 10.1371/journal.pone.0093607. eCollection 2014. | Pure hair and nail ectodermal dysplasia (PHNED) comprises a heterogeneous group of rare heritable disorders characterized by brittle hair, hypotrichosis, onychodystrophy and micronychia. Autosomal recessive (AR) PHNED has previously been associated with mutations in either KRT85 or HOXC13 on chromos ome 12p11.1-q14.3. We investigated a consanguineous Pakistani family with AR PHNED linked to the keratin gene cluster on 12p11.1 but without detectable mutations in KRT85 and HOXC13. Whole exome sequencing of affected individuals revealed homozygosity for a rare c.821T>C variant (p.Phe274Ser) in the KRT74 gene that segregates AR PHNED in the family. The transition alters the highly conserved Phe274 residue in the coil 1B domain required for long-range dimerization of keratins, suggesting that the mutation compromises the stability of intermediate filaments. Immunohistochemical (IHC) analyses confirmed a strong keratin-74 expression in the nail matrix, the nail bed and the hyponychium of mouse distal digits, as well as in normal human hair follicles. Furthermore, hair follicles and epidermis of an affected family member stained negative for Keratin-74 suggesting a loss of function mechanism mediated by the Phe274Ser substitution. Our observations show for the first time that homozygosity for a KRT74 missense variant may be associated with AR PHNED. Heterozygous KRT74 mutations have previously been associated with autosomal dominant woolly hair/hypotrichosis simplex (ADWH). Thus, our findings expand the phenotypic spectrum associated with KRT74 mutations and imply that a subtype of AR PHNED is allelic with ADWH. | 24714551 | 2014-12-01 |
| 598120126 | Autosomal-dominant woolly hair resulting from disruption of keratin 74 (KRT74), a potential determinant of human hair texture. | Shimomura Y, etal., Am J Hum Genet. 2010 Apr 9;86(4):632-8. doi: 10.1016/j.ajhg.2010.02.025. Epub 2010 Mar 25. | Autosomal-dominant woolly hair (ADWH) is a rare disorder characterized by tightly curled hair. The molecular basis of ADWH has not previously been reported. In this study, we identified a Pakistani family with ADWH. The family showed linkage to chromosome 12q12-q14.1, containing the type II keratin gene cluster. We discovered a heterozygous mutation, p.Asn148Lys, within the helix initiation motif of the keratin 74 (KRT74) gene in all affected family members. KRT74 encodes the inner root sheath (IRS)-specific epithelial (soft) keratin 74. We demonstrate that the mutant K74 protein results in disruption of keratin intermediate filament formation in cultured cells, most likely in a dominant-negative manner. Furthermore, we sequenced the mouse Krt71-74 genes in the dominant Caracul-like 4 (Cal4) allele, which is characterized by a wavy-coat phenotype and maps to the same region of mouse chromosome 15 as the Caracul (Ca) and Reduced coat (Rco) alleles. We identified a heterozygous mutation, p.Glu440Lys, not in Krt74 but in the neighboring gene, Krt71. Krt71 was previously reported to harbor Ca and Rco mutations, as well as a coding SNP that is associated with curly-coated dogs. In this study, we define the ADWH phenotype resulting from a mutation in a hair-follicle-specific epithelial keratin in humans. Our findings not only further underscore the crucial roles of the IRS-specific epithelial keratin genes Krt71-74 in hair disorders but also open the possibility that these genes might function as genetic determinants of normal variation in hair texture across mammalian species. | 20346438 | 2010-04-09 |
| 11570415 | Identification of the rat Rex mutation as a 7-bp deletion at splicing acceptor site of the Krt71 gene. | Kuramoto T, etal., J Vet Med Sci. 2010 Jul;72(7):909-12. Epub 2010 Feb 23. | The rat autosomal dominant Rex (Re) mutation on chromosome 7 causes curly hair in Re/+ and hair loss in Re/Re rats. Histopathologically, the Re/+ rat showed dilatation of the hair follicle and hairs with irregularly-coated cuticles, and the Re/Re rat showed more severe effects. We identified Re as a 7-bp deletion at the splicing acceptor site of intron 1 of the keratin 71 (Krt71) gene, which is located within the Re critical chromosomal region and plays an important role in hair formation. The deletion provoked a 6-amino acid in-frame deletion (p.Val149_Gln154del) in the alpha-helical rod domain of KRT71 protein. Identification of the Re mutation (Krt71(Re)) enables us to further understand the biological function of KRT71. | 20179389 | 2010-12-01 |
| 598119326 | Novel mutations in the keratin-74 (KRT74) gene underlie autosomal dominant woolly hair/hypotrichosis in Pakistani families. | Wasif N, etal., Hum Genet. 2011 Apr;129(4):419-24. doi: 10.1007/s00439-010-0938-9. Epub 2010 Dec 28. | Autosomal dominant woolly hair (ADWH) is an inherited condition of tightly curled and twisted scalp hair. Recently, a mutation in human keratin-74 (KRT74) gene has been shown to cause this form of hereditary hair disorder. In the present study, we have described two families (A and B) having multiple individuals affected with autosomal dominant form of hair loss disorders. In family A, 10 individuals showed ADWH phenotype while in the family B, 14 individuals showed hypotrichosis of the scalp. Genotyping using polymorphic microsatellite markers showed linkage of both the families to type II keratin gene cluster on the chromosome 12q12-14.1. Mutation analysis of the KRT74 gene identified two novel mutations in the affected individuals of the families. The sequence analysis revealed a splice acceptor site mutation (c.IVS8-1G>A) in family A and a missense variant (c.1444G>A, p.Asp482Asn) in family B. Mutations identified in the present study extend the body of evidence implicating the KRT74 gene in the pathogenesis of autosomal dominant hair loss disorders. | 21188418 | 2011-04-01 |
