Clinical characteristics and genetic diagnosis of hereditary spinocerebellar ataxia type 7 / 临床神经病学杂志

ABSTRACT

Objective To study the gene mutation and clinical characteristics of hereditary spinocerebellar ataxia type 7 (SCA7).Methods The regions of SCA7 gene containing CAG repeat were amplified by means of polymerase chain reaction (PCR) and polyacrylamide gelelectrophoresis (PAGE) technique in 112 patients with autosomal dominant SCA from 92 families, 16 sporadic SCA patients, 71 family members and 60 healthy controls. The abnormal allele fragments were sequenced by ABI377 DNA sequencing machine. The correlation between clinical manifestations and CAG repeat size in SCA7 gene product was analyzed. Results 2 patients of 6 members in 1 SCA7 family carried a 71-repeat allele. The main clinic features included ataxia, hypopsia, axanthocyanopsia and retinal pigmental degeneration. Alleles from 7 to 9 repeats were seen in the other 4 healthy members. CAG repeats from 6 to 21 were found in other 126 SCA patients, 71 family members and 60 healthy controls. Conclusions Expanded triplet repeats in SCA7 gene contributes to the pathologic phenotype, and molecular genetic analysis is effective for the diagnosis of SCA7. Retinal pigmental degeneration is an important characteristic of SCA7.