Xie Qiu-you, Liang Xiu-ling, Li Xun-hua, Feng Yan-qing
Department of Neurology, First Affiliated Hospital of Sun Yat-sen University, Guangzhou 510080, China.
Di Yi Jun Yi Da Xue Xue Bao. 2004 Jan;24(1):62-5.
To study the molecular genetic diagnosis and clinical characteristics of spinocerebellar ataxia type 7 (SCA7).
This study included 43 patients with autosomal dominant SCA from 36 families, 38 sporadic SCA patients, 60 healthy individuals from the SCA families and 44 normal controls without family SCA history. The SCA7 (CAG)n mutations were detected by PCR, denaturing polyacrylamide gel electrophoresis and silver staining technique. The abnormal allele fragments were sequenced by ABI373 DNA sequencing machine.
Normal alleles of SCA7 were found to have 9 to 19 CAG repeats. Two familial SCA and one sporadic patients were identified by detecting the presence of abnormal CAG-repeat expansion in the SCA7 alleles, which was confirmed by DNA sequencing. The repeats of CAG were 65, 65, and 63 respectively.
Abnormal CAG expansion is the pathogenic cause of SCA7. Molecular genetic analysis is effective for the diagnosis of SCA, prediction of presymptomatic patients and genetic counseling.
研究7型脊髓小脑共济失调（SCA7）的分子遗传学诊断及临床特征。
本研究纳入了来自36个家系的43例常染色体显性遗传性SCA患者、38例散发性SCA患者、60例SCA家系中的健康个体以及44例无SCA家族史的正常对照。采用聚合酶链反应（PCR）、变性聚丙烯酰胺凝胶电泳及银染技术检测SCA7（CAG）n突变。用ABI373 DNA测序仪对异常等位基因片段进行测序。
发现SCA7正常等位基因的CAG重复序列为9至19次。通过检测SCA7等位基因中异常CAG重复序列的扩增，鉴定出2例家族性SCA患者和1例散发性患者，DNA测序证实了这一结果。CAG重复序列分别为65、65和63次。
CAG异常扩增是SCA7的致病原因。分子遗传学分析对SCA的诊断、症状前患者的预测及遗传咨询有效。
