中国羌族人群强直性肌营养不良症基因CTG重复序列多态性研究

强直性肌营养不良症是由于MT-PK基因3'非编码区CTG三核苷酸重复序列的过度扩展所致。正常人群中CTG的拷贝数为5-30,而患者在50以上,且具民族差异。目前尚无我国羌族人群的有关资料。为了解中国羌族人群该基因3'UT R CTG三核苷重复序列的分布情况,作者采用PCR、聚丙烯酰胺凝胶电泳、银染和测序等技术,对60例正常羌族人的CTG重复序列进行了分析。共发现8种等位基因,其中CTG拷贝数为5的等位基因最为常见,占30 .83%,其余依次为13拷贝(22.5%)、12(19.17%)、11(15.83%)、14(5.83%)和15(4.17%);拷贝数大于15的等位基因极少,仅检测到一例,为27拷贝;CT G拷贝数在6-10之间的等位基因也很少,仅发现一例为9拷贝,而该等位基因在其它人群尚无报道。60名个体中共发现纯合子18例,其中9例为5/5,2例为11/11,2例为12/12,4例13/13和1例为15/15,杂合率为70%。本系统的多态信息量(PIC)为0.77。羌族和汉族人群该位点的多态性无显著差异。Abstract:Myotonic dystrophy is associated with an increased number of CTG repeats in the 3’UTR of the myotonic protein kinase gene(MT-PK) located on chromosome 19q13.3.The triplet repeats region of the gene of 60 healthy Qiang subjects from Sichuan province was analyzed by polymerase chain reaction and polyacrylamide gel electrophoresis.A total of 8 alleles were found ranging in size from 5 to 27copies with the most common allele of 5 copies(30.83%).The other major alleles were 11,12 and 13 copies with frequency of 15.83%,19.17% and 22.5%,respectively.An allele of 9 copies was found in a Qiang individual which has never been reported before in other populations.Only 5.83% of alleles were longer than 14 copies and one longer than 15 copies.Heterozygote frequency in this population was 70%.The CTG repeats is highly informative with a PIC value of 0.77.There is no significant difference between Qiang and Han population in the distribution of the CTG allele frequencies.

Studies of the Polymorphism of CTG Trinucleotide Repeats of Myotonic Dystrophy Gene in Qiang Nationality in China