Clinical and gene study on one pedigree of hereditary spinocerebellar ataxia type 7 / 中华神经科杂志

ABSTRACT

Objective To summarize the clinical characteristics and make genetic diagnosis in the patients with hereditary spinocerebellar ataxia type 7 (SCA7).Methods Pedigree analysis and clinical examination were performed in one family with SCA7 by clinical findings,of which retinal morphology and visual electrophysiology were available on part numbers.The polymorphic cytosine adenine guanine (CAG) repeats in the encode region of SCA7 gene were detected by combining polymerase chain reaction with deoxyribonucleic acide (DNA) sequencing on 19 familial numbers and 12 controls.Results 6 patients were identified,who manifesting cerebellar ataxia,decreased visual acuity and colour vision defect,as was pigmentary retinopathy on fundoscopy;The 6 patients had not only extinction of the electroretinogram (ERG) but also remarkably reduced amplitudes of oscillatory potentials and flash-visual evoked potentials. On normal alleles CAG repeat size ranges from 8 to 25 repeats,wherease on mutated alleles of the 6 numbers it ranges from 50 to 97 repeats.The 6 numbers were diagnosised as SCA7 patients.One asymptomatic individual of this family,who displayed a normal allele with 18 CAG repeats and another containing abnormal expantion of 56 repeats,was diagnosised as a asymptomatic carrier whose age maybe still below the age of onset.Conclusion The clinical manifestations of SCA7 are heterogeneous,and the detection of CAG repeats can provide an effective way for the gene diagnosis and the prediction of asymptomatic patients.