Identification of a novel MYO7A mutation in Usher syndrome type 1
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Ling Cheng1,2,*, Hongsong Yu1,3,*, Yan Jiang1, Juan He1, Sisi Pu1, Xin Li1 and Li Zhang1
1The First Affiliated Hospital of Chongqing Medical University, Chongqing Key Laboratory of Ophthalmology and Chongqing Eye Institute, Chongqing, P. R. China
2Department of Ophthalmology, Yongchuan Hospital, Chongqing Medical University, Chongqing, P. R. China
3Department of Immunology, Special Key Laboratory of Gene Detection & Therapy of Guizhou Province, Zunyi Medical University, Guizhou, P. R. China
*These authors have contributed equally to this work
Li Zhang, email: Zhangli298@hotmail.com
Keywords: Usher syndrome; USH1 family; MYO7A; novel mutation
Received: June 21, 2017 Accepted: December 05, 2017 Published: December 19, 2017
Usher syndrome (USH) is an autosomal recessive disease characterized by deafness and retinitis pigmentosa. In view of the high phenotypic and genetic heterogeneity in USH, performing genetic screening with traditional methods is impractical. In the present study, we carried out targeted next-generation sequencing (NGS) to uncover the underlying gene in an USH family (2 USH patients and 15 unaffected relatives). One hundred and thirty-five genes associated with inherited retinal degeneration were selected for deep exome sequencing. Subsequently, variant analysis, Sanger validation and segregation tests were utilized to identify the disease-causing mutations in this family. All affected individuals had a classic USH type I (USH1) phenotype which included deafness, vestibular dysfunction and retinitis pigmentosa. Targeted NGS and Sanger sequencing validation suggested that USH1 patients carried an unreported splice site mutation, c.5168+1G>A, as a compound heterozygous mutation with c.6070C>T (p.R2024X) in the MYO7A gene. A functional study revealed decreased expression of the MYO7A gene in the individuals carrying heterozygous mutations. In conclusion, targeted next-generation sequencing provided a comprehensive and efficient diagnosis for USH1. This study revealed the genetic defects in the MYO7A gene and expanded the spectrum of clinical phenotypes associated with USH1 mutations.
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