Analysisl Of SCA3/MJD Gene Mutation And Genetic Poiymorphism In A Family With Spinocerebellar Ataxia3

Objective：To investigate the gene mutation characteristics of a SCA3familyfrom Guangxi, to evaluate the sizes of CAG repeats, features in thetransmission and the mutation in the family with SCA3in Guangxiprovince.Methods：The fragments of SCA3/MJD gene of the members of family GXPL1were magnified by polymerase chain reaction (PCR). The products ofSCA3/MJD gene were detected with capillary electrophoresis (CE) andsequencing.Results：The10th exon of the SCA3/MJD gene in all of the affected individualsand asymptomatic carriers of the family contains between64to71CAGrepeats. The numbers of the CAG repeats during transmission between thenormal individuals carrying cgg alleles remained the same. Two novelpoint mutations were identified: IVS9-113T＞C in the intron region and 220G＞A (Glu＞Gly) in encoding region that is a missense mutation.Conclusion：1. cgg allele is not a factor leading to intergenerational instability forCAG repeats of normal individuals.2. Two novel point mutations have not been reported and the effect ofthe mutations on the phenotype of SCA3is not understood.