Trinucleotide repeat expansion of spinocerebellar ataxia (SCA1) found in a Chinese family.
OBJECTIVE
To investigate the gene mutation and the ratio of the spinocerebellar ataxia type 1 (SCA1) in Chinese patients with autosomal dominant spinocerebellar ataxia (ADSCA).


METHODS
The family material and DNA samples were collected from thirteen families with ADSCA. To determine the characteristics of the CAG trinucleotide repeats in SCA1 gene, the PCR products of the Rep1 and Rep2 primers were analyzed, and the bands with CAG repeat expansion were cloned by PCR2. 1 vector and sequenced.


RESULTS
One family was found to have an expanded CAG repeat in the 13 families with ADSCA. The clinically affected individual was heterozygous with one disease allele being 55 CAG repeats, whereas the mean size of the CAG repeats on 104 chromosomes generated from unrelated control Chinese individuals is 29.3 (ranging from 18 to 34).


CONCLUSIONS
The frequency of the SCA1 mutation is about 7% in the 13 Chinese families with ADSCA, suggesting that this type of genetic defect is not the main cause involved in the pathogenesis of ADSCA in China. Since the mutation has also been found in Caucasian, Japanese, Malaysian, and Bangladeshi kindreds, it is suggested that this genetic defect may well have multiple origins in different ethnic groups.
Cai
T
T
Laboratory of Molecular Biology, VA Medical Center, Georgetown University, Washington, DC 20422, USA.
Yu
P
P
Chen
X
X
Lopa
M
M
D000328:Adult; D017668:Age of Onset; D000483:Alleles; D044466:Asian People; D002524:Cerebellar Ataxia / Q000235:genetics*; D002681:China; D005260:Female; D006801:Humans; D008297:Male; D009154:Mutation; D010375:Pedigree; D019680:Trinucleotide Repeat Expansion / Q000235:genetics*