[Genetic and clinical phenotypic analysis of Usher syndrome-associated gene variants]

Objective:To investigate the molecular characteristics and clinical heterogeneity of Usher syndrome（USH） -related gene variants in patients with hereditary hearing loss in southwest China, providing a basis for early diagnosis and clinical management. Methods:Thirteen patients from twelve families with hearing loss who attended the Affiliated Children's Hospital of Kunming Medical University between January 2017 and March 2021 were enrolled. All patients were identified as carrying USH-related gene variants through next-generation sequencing. Sanger sequencing was performed for all patients and their parents to validate the pathogenic variants. Comprehensive clinical evaluations, including medical history collection, otologic and ophthalmologic examinations, and vestibular function assessments, were conducted. Results:Among the 13 patients, 4 were diagnosed with USH type 1 and 2 with USH type 2. A total of 19 pathogenic or likely pathogenic variants were detected in USH-related genes, including MYO7A,CDH23,USH1C, and USH2A. The causative gene was MYO7A in 3 probands, CDH23 in 5, USH1C in 3, and USH2Ain 2. All patients exhibited an autosomal recessive inheritance pattern. Vestibular dysfunction was observed in 4 patients, and retinitis pigmentosa（RP） in 3 patients. Based on the genotype-phenotype correlation, 6 patients were initially diagnosed with USH, while 7 were classified as having non-syndromic hearing loss（NSHL）. Conclusion:This study revealed the clinical heterogeneity of USH-related gene variants in patients with hereditary deafness in southwest China. Although the clinical manifestations of USH are complex and there are overlapping characteristics between different subtypes, genetic testing provides an important basis for early diagnosis and precise clinical management. Especially for those with typical hearing loss, early genetic diagnosis can provide a window of time for early detection and intervention of retinitis pigmentosa.