[Analysis and application of SCA1 and SCA3/MJD gene CAG repeats in Han population in Northeastern China].
OBJECTIVE
To investigate the normal range of (CAG)n in spinocerebellar ataxia type 1 (SCA1) gene and spinocerebellar ataxia type 3 (SCA3/MJD) gene in 110 normal subjects of Han population in Northeastern China, to assess the genotypes for clinically diagnosed spinocerebellar ataxia(SCA) individuals including 25 patients from 8 families and 6 sporadic patients, and to make presymptomatic and prenatal diagnosis.


METHODS
DNA fragments from the normal subjects and the patients were detected by fluorescence-PCR. Homozygosities were selected for DNA sequencing.


RESULTS
The normal   ranges of (CAG)n of SCA1 and SCA3/MJD were 20-39 and 14-38 repeats respectively, SCA1 was found mostly to be 26 and 27 repeats, allele frequency 34.09% and 20.91%; heterozygosity was 84.55%, SCA3/MJD was found mostly to be 14 repeats, allele frequency 39.55%, heterozygosity was 78.18%.(CAG)(68) of SCA3/MJD gene of one affected individual had been found in a family but no CAG mutative expansion in related members was observed.


CONCLUSIONS
The normal ranges of CAG repeats vary with areas and races. SCAs genotyping is the first choice in presymptomatic and prenatal diagnosis.
Jiang
Miao
M
Department of Medical Genetics, China Medical University, Shenyang, Liaoning, PR China.
Jin
Chun-lian
CL
Lin
Chang-kun
CK
Qiu
Guang-rong
GR
Liu
Zong-lan
ZL
Wang
Chao-xiang
CX
Sun
Kai-lai
KL
D000067696:Ataxin-1; D000067699:Ataxin-3; D000067528:Ataxins; D002681:China; D004247:DNA / Q000737:chemistry / Q000235:genetics; D005192:Family Health; D005260:Female; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D017827:Machado-Joseph Disease / Q000175:diagnosis / Q000235:genetics; D008297:Male; D009419:Nerve Tissue Proteins / Q000235:genetics*; D009687:Nuclear Proteins / Q000235:genetics*; D010375:Pedigree; D012097:Repressor Proteins; D017422:Sequence Analysis, DNA; D020754:Spinocerebellar Ataxias / Q000175:diagnosis / Q000235:genetics; D019680:Trinucleotide Repeat Expansion / Q000235:genetics; D018911:Trinucleotide Repeats / Q000235:genetics*
C000593749:ATXN1 protein, human; D000067696:Ataxin-1; D000067528:Ataxins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D012097:Repressor Proteins; D004247:DNA; C092341:ATXN3 protein, human; D000067699:Ataxin-3