Molecular diagnose of a large hearing loss population from China by targeted genome sequencing

Hereditary hearing loss is genetically heterogeneous, with diverse clinical manifestations. Here we performed targeted genome sequencing of 227 hearing loss related genes in 1027 patients with bilateral hearing loss and 520 healthy volunteers with normal hearing to comprehensively identify the molecular etiology of hereditary hearing loss in a large cohort from China. We obtained a diagnostic rate of 57.25% (588/1027) for the patients, while 4.67% (48/1027) of the patients were identified with uncertain diagnoses. Of the implicated 35 hearing loss genes, three common genes, including SLC26A4(278/588), GJB2(207/588), MT-RNR1(19/588), accounted for 85.54% (503/588) of the diagnosed cases, while 32 uncommon hearing loss genes, including MYO15A, MITF, OTOF, POU3F4, PTPN11, etc. accounted for the remaining diagnostic rate of 14.46% (85/588). Apart from Pendred syndrome, other eight types of syndromic hearing loss were also identified. Of the 64 uncertain significant variants and 244 pathogenic/likely pathogenic variants identified in the patients, 129 novel variants were also detected. Thus, the molecular etiology presented with high heterogeneity with the leading causes to be SLC26A4 and GJB2 genes in the Chinese hearing loss population. It's urgent to develop a database of the ethnicity-matched healthy population as well as to perform functional studies for further classification of uncertain significant variants.