Identification of a novel CLRN1 gene mutation in Usher syndrome type 3: two case reports

Objective: This study examines the CLRN1 gene mutation analysis in Japanese patients who were diagnosed with Usher syndrome type 3 (USH3) on the basis of clinical findings.

Methods: Genetic analysis using massively parallel DNA sequencing (MPS) was conducted to search for 9 causative USH genes in 2 USH3 patients.

Results: We identified the novel pathogenic mutation in the CLRN1 gene in 2 patients. The missense mutation was confirmed by functional prediction software and segregation analysis. Both patients were diagnosed as having USH3 caused by the CLRN1 gene mutation.

Conclusion: This is the first report of USH3 with a CLRN1 gene mutation in Asian populations. Validating the presence of clinical findings is imperative for properly differentiating among USH subtypes. In addition, mutation screening using MPS enables the identification of causative mutations in USH. The clinical diagnosis of this phenotypically variable disease can then be confirmed.