RGD Reference Report - An USH2A founder mutation is the major cause of Usher syndrome type 2 in Canadians of French origin and confirms common roots of Quebecois and Acadians. - Rat Genome Database

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An USH2A founder mutation is the major cause of Usher syndrome type 2 in Canadians of French origin and confirms common roots of Quebecois and Acadians.

Authors: Ebermann, I  Koenekoop, RK  Lopez, I  Bou-Khzam, L  Pigeon, R  Bolz, HJ 
Citation: Ebermann I, etal., Eur J Hum Genet. 2009 Jan;17(1):80-4. doi: 10.1038/ejhg.2008.143. Epub 2008 Jul 30.
RGD ID: 8547965
Pubmed: PMID:18665195   (View Abstract at PubMed)
PMCID: PMC2985947   (View Article at PubMed Central)
DOI: DOI:10.1038/ejhg.2008.143   (Journal Full-text)

Congenital hearing loss affects approximately one child in 1000. About 10% of the deaf population have Usher syndrome (USH). In USH, hearing loss is complicated by retinal degeneration with onset in the first (USH1) or second (USH2) decade. In most populations, diagnostic testing is hampered by a multitude of mutations in nine genes. We have recently shown that in French Canadians from Quebec, USH1 largely results from a single USH1C founder mutation, c.216G>A ('Acadian allele'). The genetic basis of USH2 in Canadians of French descent, however, has remained elusive. Here, we have investigated nine USH2 families from Quebec and New Brunswick (the former Acadia) by haplotype analyses of the USH2A locus and sequencing of the three known USH2 genes. Seven USH2A mutations were identified in eight patients. One of them, c.4338_4339delCT, accounts for 10 out of 18 disease alleles (55.6%). This mutation has previously been reported in an Acadian USH2 family, and it was found in homozygous state in the three Acadians of our sample. As in the case of c.216G>A (USH1C), a common haplotype is associated with c.4338_4339delCT. With a limited number of molecular tests, it will now be possible in these populations to estimate whether children with congenital hearing impairment of different degrees will develop retinal disease - with important clinical and therapeutic implications. USH2 is the second example that reveals a significant genetic overlap between Quebecois and Acadians: in contrast to current understanding, other genetic disorders present in both populations are likely based on common founder mutations as well.

RGD Manual Disease Annotations    Click to see Annotation Detail View
TermQualifierEvidenceWithReferenceNotesSourceOriginal Reference(s)
Usher syndrome type 2 susceptibilityIAGP 8547965DNA:insertion more ...RGD 
Usher syndrome type 2 susceptibilityISOUSH2A (Homo sapiens)8547965; 8547965DNA:insertion more ...RGD 

Objects Annotated

Genes (Rattus norvegicus)
Ush2a  (usherin)

Genes (Mus musculus)
Ush2a  (usherin)

Genes (Homo sapiens)
USH2A  (usherin)


Additional Information