Whole exome sequencing identifies novel USH2A mutations and confirms Usher syndrome 2 diagnosis in Chinese retinitis pigmentosa patients

Retinitis pigmentosa (RP) is a common phenotype in multiple inherited retinal dystrophies (IRD). Disease gene identification can assist the clinical diagnosis of IRD patients for better clinical management, treatment and counseling. In this study, we aimed to delineate and characterize the disease-causing mutations in Chinese familial and sporadic patients with initial diagnosis of RP. Four unrelated Chinese families and 118 sporadic RP patients were recruited for whole exome sequencing analysis. A total of 5 reported and 3 novel USH2A mutations were identified in four Chinese probands. The probands and their family members showed typical RP features and mild to severe hearing impairment, confirming the diagnosis of Usher syndrome 2 (USH). Moreover, 11 sporadic RP patients were identified to carry the compound heterozygous mutations in the USH2A gene, confirming the diagnosis of USH2. The patients carried the truncating mutations had a younger age of first visit than the patients carried only the missense mutations (p = 0.017). In summary, this study revealed 8 novel USH2A variants in Chinese familial and sporadic RP patients, assuring that whole exome sequencing analysis is an adequate strategy to facilitate the clinical diagnosis of USH from the sporadic RP patients.