Novel mutations of the USH2A gene cause Usher syndrome in five Chinese families.

BACKGROUND

Usher syndrome (USH) is a leading disorder of deaf-blindness. The phenotypic and genetic heterogeneity of USH makes the diagnosis of this disorder difficult. However, diagnosis can be facilitated by employing molecular approaches, especially for diseases without pronounced pathognomonic symptoms. Therefore, this study aimed to reveal the genetic defects in five USH patients using clinical targeted exome sequencing (TES).

METHODS

USH patients and their family members from five unrelated Chinese USH families were recruited and subjected to TES. Ophthalmic information was obtained for all patients to ensure a meaningful interpretation. The TES data were analysed using an established bioinformatics pipeline to identify causative mutations. Further verification by Sanger sequencing and cosegregation analysis were performed on available family members.

RESULTS

We identified genetic mutations in five USH patients using TES. Seven mutations, four of which were novel, were identified in the USH2A gene. One proband (F1-II-3) was found to have a homozygous mutation inherited from nonconsanguineous parents, and another proband (F5-III-1) was found to carry three USH2A gene mutations.

CONCLUSION

In conclusion, the study revealed the importance of TES in the clinical diagnosis of USH patients with variable phenotypes. The correlation between USH2A gene mutations and clinical phenotypes will help to refine the clinical diagnosis of USH.