一个常染色体隐性遗传性耳聋家系中MYO7A基因的突变与遗传分析

Mutation and genetic analysis of MYO7A in a family with autosomal recessive hearing loss

摘要:

目的 对一个常染色体隐性遗传的先天性耳聋核心家系进行遗传学分析，探究该家系的致病基因。方法 对该耳聋家系成员进行病史采集、体格检查及听力学检查，分析家系的遗传特征并绘制家系图，通过高通量测序对先证者进行耳聋基因筛查，使用Sanger测序在家系中对可疑致病位点进行共分离分析。结果 该家系2代4人，1名耳聋患者，为常染色体隐性遗传；高通量测序发现先证者MYO7A基因存在NM_000260.3:c.765C>A（p.F255L）和c.275_278dupACCT（p.I94fs）两个新的突变位点，依据ACMG变异分类指南判定为可疑致病性和致病性变异；经Sanger测序验证c.765C>A突变来自父亲，c.275_278dupACCT突变来自于母亲，姐姐携带c.765C>A突变，变异在家系中与表型共分离。结论 MYO7A基因新的复合杂合突变c.765C>A和c.275_278dupACCT与上述常染色体隐性遗传性耳聋密切相关，丰富了MYO7A基因突变谱，为遗传性耳聋的遗传咨询提供依据。

Abstract:

Objective To analyze the causative mutation of an autosomal recessive nuclear family with congenital hearing loss. Methods Medical histories collection, detailed physical examination and hearing test were performed on the family members. High throughput sequencing was conducted for screening of hearing loss genes. Suspected mutations were analyzed by Sanger sequencing. Results There were 4 people of 2 generations in this autosomal recessive family, one member with hearing loss. High throughput sequencing and Sanger sequencing revealed the proband carrying compound heterozygous mutation of MYO7A, NM_000260.3:c.765C>A（p.F255L）from her father and c.275_278dupACCT（p.I94fs）from her mother, and her sister carried the c.765C>A mutation. According to the ACMG, c.765C>A was classified as likely pathogenic and c.275_278dupACCT classified as pathogenic. Conclusion Novel compound heterozygous mutation of MYO7A was identified as the causative mutation for congenital hearing loss in this family. This finding enriched the mutation spectrum of MYO7A and provide a basis for genetic counseling of hereditary hearing loss.