Two truncating USH3A mutations, including one novel, in a German family with Usher syndrome.

PURPOSE:To identify the genetic defect in a German family with Usher syndrome (USH) and linkage to the USH3A locus. METHODS:DNA samples of five family members (both parents and the three patients) were genotyped with polymorphic microsatellite markers specific for eight USH genes. Three affected family members underwent detailed ocular and audiologic characterization. RESULTS:Symptoms in the patients were compatible with Usher syndrome and show intrafamilial variation, for both hearing loss (ranging from severe to profound with non-linear progression) and vision. Genotyping of microsatellite markers for the different USH loci was in line with a defect in the USH3A gene on chromosome 3q25. Sequence analysis of the USH3A gene revealed two truncating mutations; c.149_152delCAGGinsTGTCCAAT, which has been described previously, and a novel mutation, c.502_503insA, segregating with the phenotype. CONCLUSIONS:To date, only 11 USH3A mutations have been described. This is the first description of a German family with USH due to USH3A mutations, including one novel. Our findings indicate that also in the Central European population, USH3A mutations should be considered in cases of USH.

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