Clinical and genetic study of spinocerebellar ataxias 3 within a consanguinity family / 中华神经科杂志

ABSTRACT

Objective To investigate the inheritance principle of the expanded GAG repeat allele and the clinical features of spinocerebellar ataxias 3 (SCA3) in a consanguinity family with first cousin marriage.Methods The CAG repeats of SCA3 gene were amplified by means of polymerase chain reaction.Fragment analysis with laser-induced fluorescence in capillary electrophoresis were performed for the positive samples detected by agarose gel electrophoresis.Furthermore,the clinical features were analyzed carefully.Results Fragment analysis revealed that the proband carried 2 alleles with 56 and 72 CAG repeats separately.The proband' s father carried 28 and 66,and the expanded CAG repeat allele inherited from his grandfather.The proband' s mother carried 33 and 56,and the expanded CAG repeat allele inherited from his grandmother.The proband' s son carried 27 and 85 and presented with dystonia besides ataxia.Conclusions The proband' s parents have the common ancestors.Their alleles with expanded CAG repeats probably come from the same allele of their ancestor.The GAG repeat is more unstable in the paternal inheritance than in the maternal inheritance.The 71-year-old asymptomatic family member carry the allele with 56 CAG repeats,which indicates the 56 CAG repeats may be not associated with the disease.The patients within this family have variable clinical features,especially the juvenile-onset case presents with apparent dystonia.