一个肢带型肌营养不良家系的临床和分子遗传学分析

目的 研究1个肢带型肌营养不良(limb girdle muscular dystrophy,LGMD)家系的临床表现,并应用基因突变分析、基因组扫描技术和连锁分析对该家系进行分子遗传学分析.方法 对1个来自浙江的连续4代发病的LGMD家系进行家系调查和体格检查,先证者行电生理检查及肌肉病理活体组织检查分析;26名家系成员在知情同意的情况下抽取基因组DNA进行基因突变分析、基因组扫描和连锁分析.结果 家系分析证明该家系符合常染色体显性遗传,家系中存在遗传早现现象,主要表现为四肢近端肌无力,无构音障碍、肌强直;电生理检查和肌肉活体组织检查符合肌肉病变特点;基因突变分析未发现LGMD1A、1B、1C和面肩肱型肌营养不良(FSHD)基因的致病突变;基因组扫描和连锁分析显示该家系致病基因与已报道的LGMD1D和LGMD1F的染色体区间连锁关系不成立.结论 LGMD家系患者的临床表现具有高度异质性,该家系的致病基因不在已报道的位点内,推测可能存在新的致病位点或是一种新的LGMD遗传类型.

Clinical features and molecular genetic analysis of a pedigree of limb girdle muscular dystrophy

Objective To investigate the clinical features and analyze the molecular genetics of a pedigree of limb girdle muscular dystrophy (LGMD).Methods Pedigree analysis and clinical examination were performed in one four-generation family with LGMD.Electrophysiology and muscle biopsy were done in the affected members.With an informed consent, gene mutation, genome screening and linkage analysis were conducted in 26 members of this pedigree.Results Seven patients were identified.Pedigree analysis was consistent with autosomal dominant inheritance.Affected members had early presentation.Main features included proximal muscle weakness without dysarthria nor spasticity; electrophysiology and muscle biopsy revealed myopathic changes.LGMD1 A, 1B, 1C and facioscapulohumeral dystrophy genes were not detected by gene mutation analysis.Genome screening and linkage analysis did not reveal any linkage with the disease-causing gene and the reported loci of LGMD1D and LGMD1F genes.Conclusions The clinical manifestations of this LGMD family are highly heterogeneous, and the disease-causing gene of this family is not linked to any of the reported sites, suggesting this may be a new disease-causing locus, or a new genetic type of LGMD.