一个遗传性共济失调7型家系的基因突变分析

Mutation analysis of a Chinese family with spinocerebellar ataxia 7

目的 研究1个遗传性共济失调7型回族家系的临床表现与基因突变特点.方法 应用聚合酶链反应、分子克隆及测序等方法对1个临床诊断为遗传性共济失调的回族家系进行SCA7基因检测,对异常片段进行分子克隆测序.结果 证实该家系为遗传性共济失调7型家系,视网膜退行性变为其相对独特的临床表现.先证者父亲异常片段CAG重复为46次;先证者异常片段CAG重复次数为54次,发病年龄较父代提前22年.结论 报告1个遗传性共济失调7型回族家系,该亚型明显的遗传早现及病程进展与CAG重复次数的不稳定扩增相关.

Objective To characterize the clinical phenotype and the gene mutation of the spinocerebellar ataxia 7 （SCA7） family. Methods Two patients from a two generation Hui Chinese pedigree were detected by gene test. Polymerase chain reaction （PCR） for CAG trinucleotide repeats was performed for the SCA7 gene, and the fragments with expanded alleles were subcloned into the pGEM-T plasmids and sequenced. Results Molecular analysis demonstrated the pathological expansions in the SCA7 gene, with 46 CAG repeats in the expanded allele of the proband＇s father. The 46 repeats expanded to 54 repeats in the proband with marked anticipation of approximately 22 years. Conclusion This family was the first SCA7 Hui Chinese family reported. Retinal degeneration is relatively unique to SCA7. The instability of the expanded triplet repeats accounts for the marked anticipation and the rate of progression of the disease.