title: [Analysis and application of SCA1 and SCA3/MJD gene CAG repeats in Han population in Northeastern China].
abstract: 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.
authors.affiliation: Department of Medical Genetics, China Medical University, Shenyang, Liaoning, PR China.
authors.forename: Miao
authors.initials: M
authors.lastname: Jiang
authors.forename: Chun-lian
authors.initials: CL
authors.lastname: Jin
authors.forename: Chang-kun
authors.initials: CK
authors.lastname: Lin
authors.forename: Guang-rong
authors.initials: GR
authors.lastname: Qiu
authors.forename: Zong-lan
authors.initials: ZL
authors.lastname: Liu
authors.forename: Chao-xiang
authors.initials: CX
authors.lastname: Wang
authors.forename: Kai-lai
authors.initials: KL
authors.lastname: Sun
mesh_terms: 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*
chemical_list: 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