Objective      To undertake a clinical and genetic spectrum analysis in patients with hereditary spinocerebellar ataxia (SCA) in Chongqing district.       Methods      SCA 1

2

3

6

7

12

17 and dentatorubral-palliodoluysian atrophy (DRPLA) nucleotide repeat mutations were detected in 10 autosomal dominant SCA families and 9 sporadic SCA patients by PCR

agarose gel electrophoresis and DNA sequencing. The clinical data was also analyzed.       Results      There were 8 SCA3 families

the other 2 families and the sporadic cases were genetically unidentified. In the 8 SCA3 families

15 patients were confirmed

with CAG repeat 58 to 71 times. Seven family members diagnosed to be presymptomatic patients

with CAG repeat 56 to 71 times. There was typical genetic anticipation

with  cerebellar ataxia

dysarthria and tentorium brain atrophy.       Conclusion      SCA3 is substantially the most common subtype in SCA patients in Chongqing district

manifested by cerebellar ataxia

dysarthria and tentorium brain atrophy. The clinical symptoms are more serious in sporadic SCA patients than SCA patients with familly history. The degree of brain stem atrophy is associated with the course of disease

and the longer the duration

the more serious the brain stem atrophy.