Ophthalmology in China

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Genotype and clinical characteristics of Usher syndrome patients with pathogenic mutations in MYO7A gene

Ye Hanwen, Sun Tengyang, Xu Ke, Xie Yue, You Bing, Li Yang   

  1. Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Key Laboratory of Ophthalmology and Visual Sciences, Beijing 100005, China
  • Received:2019-09-17 Online:2020-03-25 Published:2020-03-25
  • Contact: Li Yang, Email: yanglibio@aliyun.com
  • Supported by:
    National Natural Science Foundation of China(81570886)

Abstract: Objective To analyze genotype and clinical characteristics of Usher syndrome patients with pathogenic mutations in MYO7A. Design Retrospective case series. Participants 33 Chinese probands (14 from Beijing Tongren Hospital and 19 probands from 10 related literatures) with pathogenic mutations in MYO7A gene. Methods All patients underwent ophthalmic examinations including best-corrected visual acuity, fundus examinations, retinal optical coherence tomography, and flash-electroretinogram, and auditory examinations including pure-tone audiometry, acoustic immittance tests, and otoacoustic emission tests. The patients were classified into Usher syndrome type 1 (USH1) and Usher syndrome type 2 (USH2) according to their clinical characteristics. Main Outcome Measures Mutations in MYO7A gene, age of onset, and degree of hearing impairment. Results Of the 33 probands, 27 probands presented with USH1 and 6 probands presented with USH2. A total of 44 mutations of MYO7A gene were detected in these patients, including 17 missense mutations, 6 nonsense mutations, 12 splicing mutations, 6 frame-shift mutations, and 2 copy number variants. The rate of missense mutations in USH2 patients (9/12, 75.0%) was significantly higher than that in USH1 patients (21/54, 38.9%). The rate of nonsense mutations (12.1%) was significantly lower than that in Caucasians. The rate of splicing mutations (19.7%) and frame-shift mutations (19.7%) was higher than that in Caucasians. The mutation p.1240R>Q that was most common in Caucasians was not found in these patients. Conclusion This study preliminarily confirms the mutation spectrum of MYO7A in Chinese Usher syndrome patients, which differs from that in Caucasians. Usher syndrome patients with missense mutations have milder hearing impairment. (Ophthalmol CHN, 2020, 29: 98-103)

Key words: Usher syndrome typeⅠ, Usher syndrome typeⅡ, MYO7A gene