The characteristics of CAGrepeat in the CACNA1A gene in the Chinese Han population and its application in moleculardiagnosis of spinocerebellar ataxia type 6

Abstract

：Objective To investigatedistribution of CAG repeat in the CACNA1A gene in theChinese Han population and itsapplication in molecular diagnosis of spinocerebellar ataxia type 6(SCA6).Methods Thetrinucleotide repeats of CAG were detected by two-step polymerase chainreaction(PCR).denaturing polyacrylamide gel electrophoresis(DPAGE)and DNA sequencing in300 normal individuals and 109 unrelated SCA patients.Results In normal individuals.thenumber of CAG repeats ranged from 3 to 18 with 13 being the most frequent repeats.In 109SCA patients,one patient was identified of 24 repeats and was diagnosed with SCA6.Thispatient's mother and elder brother were also SCA6 patients.They all showed slowlyprogressive cerebellar ataxia,dysarthria,nystagmus,minor impairment in vibration sensationand proprioeeptive sensation in clinical manifestation with obviousanticipation.Conclusions SCA6 is rare in the Chinese Population.Mutation analysis of theCACNA1A gene is helpful for clinical diagnosis of SCA6.Two-step PCR increases theefficieney of molecular diagnosis in SCA6.