Usher综合征Ⅱ型家系临床表型特征及USH2A基因突变分析

Clinical features and genetic analysis of a Chinese family with Usher syndrome type Ⅱ

目的对收集到的一个Usher综合征家系的临床表型特征进行分析,并选取USH2A基因进行突变检测。方法通过填写问卷式调查表对家系进行详细的病史调查,绘制家系遗传图谱;依据详细的全身和专科检查结果对家系进行分型诊断,对家系耳聋患者进行USH2A基因突变分析。结果该家系双耳听力下降出现在3～4岁,非渐进性,30～50岁听力学检测表现为中重度感音神经性耳聋,以高频听力损失为主,前庭功能正常。该家族耳聋患者10～13岁时出现夜盲,随年龄增长逐渐加重,视野逐渐缩窄至管状视野,伴视力下降。USH2A基因突变分析检测到9种单核苷酸多态,其中c.504A>G(T168T)、c.879T>G(L293L)、IVS15+35G>A、IVS18-8T>G、c.4457G>A(R1486K)为已知单核苷酸多态,c.573A>G(V191V)、c.1276A>T(N426Y)、IVS19-44G>A、IVS19-66A>C为本研究首次报道。结论本文报导的Ⅱ型Usher综合征家系具有独特的临床表型特征,对该家系USH2A基因突变分析未发现最常见的2299delG突变及其他明确与疾病相关的新突变,提示Usher综合征具有高度的遗传异质性。

Objective To analyze the clinical and genetic features of a Chinese Usher syndrome family, and to identify the mutations of USH2A gene. Methods The medical history was taken using a structured questionnaire. General physical examinations and otological and ophthalmological examinations were conducted in this family. Direct DNA sequencing was applied to identify the mutations of USH2A gene. Results All Patients in this family have had bilateral, non-progressive, moderate to severe sensorineural hearing loss since childhood. The vestibular symptoms were not reported by any affected subjects and no vestibular dysfunction was detected in the patients. Progressive retinitis pigmentosa was detected in all the patients, with the appearance of vision decrease and night blindness occurring in the first decade. Four single nucleotide polymorphisms（SNPs） were firstly identified in the USH2A, including c.573A〉G（V191V）, c.1276A〉T（N426Y）, IVS19-44G〉A, IVS19-66A〉C. Five SNPs, which were previously reported, c.504A〉G（T168T）, c.879T〉G（L293L）, IVS15＋35G〉A, IVS18-8T〉G, c.4457G〉A（R1486K）, were also identified in this family. Conclusion Nine SNPs of the USH2A gene were identified in Chinese Usher syndrome typeⅡpatients.