8例腓骨肌萎缩症患者的二代测序遗传学特征分析

Next-generation sequencing genetic characteristics of Charcot-Marie-Tooth disease in 8 cases

目的总结腓骨肌萎缩症(Charcot-Marie-Tooth, CMT)的遗传学特征,探讨二代测序技术在CMT诊断中的应用价值。方法回顾性分析8例CMT患者的临床表现、体征及神经电生理检查结果,采用CMT神经功能障碍评分评估周围神经功能障碍程度;采用二代测序技术检测基因突变情况,对错义突变位点,在1000Genom数据库、HGMD数据库进行比对,判断是否具有单核苷酸多态性,应用SIFT、PolyPhen2、Mutation-Taster等软件预测基因突变的致病性。结果8例首发症状均为双下肢无力,双下肢远端肌肉萎缩,双下肢腱反射减弱或消失。神经电生理检查提示神经源性脱髓鞘合并轴索损害,CMT神经功能障碍评分均提示中度周围神经功能障碍。二代测序结果显示染色体单倍重复1例(PMP22基因在此区域内),PMP22基因重复突变4例,MPZ基因错义突变(c.233C>T、c.293G>A)2例,NEFL基因错义突变(c.65C>A)1例,其中4例PMP22基因重复突变,2例MPZ基因错义突变为致病性突变,1例染色体单倍重复(PMP22基因包含此区域内)及1例NEFL基因错义突变为可能致病性突变。结论二代测序技术有助于CMT的精准诊断,PMP22重复突变、MPZ c.233C>T、MPZ c.293G>A及NEFL c.65C>A错义突变可导致CMT。

Objective To observe the genetic characteristics of Charcot-Marie-Tooth(CMT) disease, and explore the value of next-generation sequencing(NGS) to the diagnosis of CMT disease. Methods The clinical manifestations, physical signs and electroneurography examination results were retrospectively analyzed in 8 cases of CMT disease. CMT neuropathy score was used to assess the degree of peripheral nerve dysfunction. NGS was used to detect gene mutations, and missense mutations were compared in 1000 Genom database and HGMD database to determine whether there were single nucleotide polymorphisms. The pathogenicity of gene mutations was predicted by using SIFT, PolyPhen2 and Mutation-Taster softwares. Results All patients presented initially with double lower limbs weakening, distal muscle atrophy and tendon reflexes weakening or disappeared. Electrophysiological examination showed neurogenic demyelination combined with axonal injury. CMT neuropathy score showed moderate peripheral nerve dysfunction in all patients. NGS results showed chromosome haploidy in 1 patient(including PMP22 gene), PMP22 gene duplication mutation in 4, MPZ missense mutation(c.233 C>T, c.293 G>A) in 2 and NEFL missense mutation(c.65 C>A) in 1, in which PMP22 duplication mutation in 4 and MPZ missense mutation in 2 were pathogenic mutations, while chromosome haplotype(including PMP22 gene) in 1 and NEFL missense mutation in 1 were possible pathogenic mutations. Conclusion NGS is helpful to the accurate diagnosis of CMT disease. PMP22 duplication mutation, MPZ c.233 C > T, MPZ c.293 G > A and NEFL c.65 C > A missense mutations would lead to CMT disease.