中国汉族腓骨肌萎缩症家系的CX32基因突变和临床特点分析

Analysis of CX32 gene mutation and related clinical features in Chinese Han Charcot-Marie-Tooth families

目的 分析中国汉族腓骨肌萎缩症（CMT）家系CX32基因突变及相应临床特点。方法应用多聚酶链反应结合DNA直接测序法对34个于2004-2011年由湘雅医院、湘雅三医院神经内科门诊和医学遗传学国家重点实验室遗传门诊收集无PMP22基因大片段重复突变，无男传男的腓骨肌萎缩症家系进行CX32基因突变检测，并分析6个CMTXl家系中11例患者的临床、电生理及神经病理特点。结果 发现6个CMTXl家系5个CX32基因突变：c．37G〉A、c．65G〉A、e．246C〉G、c．256A〉G和c．533A〉G，其中c．246C〉G、c．533A〉G为新发现的突变。CMTXl型临床特点为具有典型远端肌肉萎缩无力、腱反射减退或消失、弓形足等症状及体征，神经电生理示神经传导速度介于21．7～49．3m／s，神经活检示髓鞘脱失、轴索变性均存在。结论CX32基因突变频率在本研究CMT人群中约占9％，CMT家系具有男性患者较女性患者表型重、电生理和病理为中间型改变等特点，CX32基因突变分析有助于明确CMT患者基因诊断、开展遗传咨询和生育指导，以及进一步的发病机制研究。

Objective To analyze the mutation of CX32 gene and related clinical features in Chinese Han patients with Charcot-Marie-Tooth （CMT） disease. Methods Thirty-four CMT families, from 2004 to 2011 at Departments of Neurology, Xiangya Hospital, Third Xiangya Hospital and National Key Laboratory of Medical Genetics, were selected for CX32 mutation screening after the exclusion of the PMP22 duplication and male-to-male transmission. Mutation analysis was carried out by polymerase chain reaction （PCR） plus direct sequencing. Analyses of clinical, electrophysiological and pathological features in 11 patients from 6 CMTX1 families were performed by 2 neurologists. Results Five CX32 gene mutations were detected in 6 CMT families： c. 37G 〉 A, c. 65G 〉 A, c. 246C 〉 G, c. 256A 〉 G and c. 533A 〉 G. Among them, c. 246C 〉 G and c. 533A 〉 G were firstly reported. The clinical manifestations included progressive distal muscle atrophy and weakness, areflexia, sensory abnormalities and pes vacus. Nerve conduction velocity ranged from 21.7 to 49.3 m/s. Both demyelination and axonal degeneration were detected in nerve biopsy. Conclusions CMT1X has a frequency of around 9% in our study. The male patients tend to have more serious clinical features and their electrophysiological and pathological changes are intermediate. CX32 mutation analysis helps to confirm the genetic diagnosis of CMT so as to provide genetic counseling and reproductive guidance and elucidate its pathogenesis.