进行性肌营养不良症基因诊断及家系分析

Gene diagnosis and pedigree analysis in families of Duchenne and Becker muscular dystrophy

目的 在假肥大型进行性肌营养不良症家系中进行基因诊断与遗传咨询。方法 用多重聚合酶链反应方法扩增dystrophin基因 9对外显子 ,检测有无外显子缺失 ,用聚合酶链反应方法扩增位于dystrophin基因内含子及 5′、3′端的短串联重复顺序 ,所得产物进行等位片段长度多态性连锁分析。结果 在 2个肌营养不良家系中检测到外显子及重复顺序片段缺失 ,在 1个家系中仅发现重复顺序片段缺失 ,在 1例散发家系中未发现缺失。通过分析均得到正常染色体、致病染色体与有再发风险的染色体单体型。结论 多重聚合酶链反应与短串联重复顺序多态性分析方法 ,可在Duchenne型和Becker型肌营养不良家系进行基因诊断、携带者检测及遗传咨询。

Objective Gene diagnosis and pedigree analysis were carried out in families of Duchenne and Becker muscular dystrophy(DMD and BMD) in order to determine haplotypes in the patients, carriers and normal offspring. Methods Deletion analysis of the patients was performed using multiplex polymerase chain reaction of amplification with 9 dystrophin exons described by Chamberlain et al. Allelic fragment length polymorphism analysis was made on DNA with PCR amplification using primers of intragenic short tandem repeat (STR) sequences (STR44、 STR45、 STR49 and STR50), primers of 5′ end (5′DYS II) and primers of 3′end (MZ18、 MZ19) in the members of the families. Results Deletions of exons as well as deletions of STR allelic fragments adjacent to the exon deletions were determined in two patients, hemizygosity at those loci was detected and carrier status ascertained in the mothers of the patients. The normal haplotypes were determined in some relatives of the patients. Deletion of allelic fragment of STR49 was found in a patient of the anather family with DMD and carrier status ascertained in the mother of the patient. No deletion was detected in the sporadic BMD family,but risk haplotype was determined. Conclusion The method of linkage analysis of STR sequence polymorphism can determine haplotypes at normal status or at risk status. It may be used in gene diagnosis, prenatal diagnosis and carrier detection in the families of Duchenne and Becker muscular dystrophy