Analysis And Application Of Spinocerebellar Ataxia Type 1,2(SCA1,SCA 2) Gene And Mitochondrial DNA Partly Mutations In SCA1,SCA 2

Objective:Analysis and application of spinocerebellar ataxia type 1,2(SCA1,SCA2)gene and the possible relationship between mitochondrial DNA(mtDNA)and SCA1,SCA2.Methods:1.The part one of this study included 38 patients and 64 their relatives with autosomal dominant SCA from 15 kindreds and 11 sporadic SCA patients.Fluorescence-PCR and fragment analysis with capillary electrophoresis was applied to count the CAG-repeat expansion of SCA1,2 gene and was proved with sequencing.2.Polymerase chain reaction(PCR)was used to amplify 2 mtDNA segments of 7 patients and presymptomatic individuals,35volunteers. The point 8344 and 11778 lied in the above 2 mtDNA segments respectively. For PCR products of point 8344 and 11778,single strand conformation polymorphism(SSCP)was executed to detect mutations and the abnormal segments were sequenced.Results:1.5 patients and presymptomatic relatives were confirmed by detecting the presence of abnormal CAG-repeat expansion in SCA1 gene.2 patients and presymptomatic relatives were confirmed by detecting the presence of abnormal CAG-repeat expansion in SCA2 gene.2.We had not found mutation in the segments point 8344 lied in.However,a new mtDNA mutation,deletion mutation in segments of mtDNA point 11893A→G,was identified in 2 SCA1patient and 1 presymptomatic relatives. Conclusion:We can made genetic diagnosis of SCA1,SCA2 by detecting the CAG- repeat expansion of SCA1,SCA2 gene.The frequcncy of SCA3 is substantially higher than that of SCA1 and SCA2 in the autosomal dom inant SCA patients.SCA6 and SCA7 are rare subtypes.The new deletion mutation of mtDNA may be related to SCA1.