Mutation analysis of a Chinese family with spinocerebellar ataxia 7

Abstract

To characterize the clinical phenotype and the gene mutation of the spinocerebellar ataxia 7 (SCA7) family. 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. 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. 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.