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强直性肌营养不良是由于ＭＴ－ＰＫ基因３＇非编码区ＣＴＧ三核苷酸重复序列的过度扩增。文献报道一般正常人ＣＴＧ的拷贝数为５～３５次，而患者在５０次以上，且有民族差异。目前尚无我国人群的资料。为了解中国汉族人群ＣＴＧ三核苷酸重复序列的分布情况，采用ＰＣＲ聚丙烯酰胺凝胶电泳和银染等技术，对成都地区１５９例正常汉族人该重复序列进行了分析，发现汉族与其它民族ＣＴＧ重复序列的拷贝数分布不尽相同，在分析的３１８条染色体中，共发现１４种等位基因，其中ＣＴＧ拷贝数以５的频率最高，占３９．３％，其余依次为１１拷贝（２０．７５％）、１２拷贝（１８．２４％）、１３拷贝（１１．３２％）及１０拷贝（４．０９）．拷贝数大于１４的等位基因很少，占４．０８％，拷贝数大于１９的等位基因更少，仅占０．９４％。此外拷贝数为６～９的等位基因很少，仅６拷贝和８拷贝的等位基因各一个。共发现纯合子４０例，其中：２６例５／５，６例１１／１１，５例１２／１２和３例１３／１３，杂合率为７４．８％，本系统的多态信息容量值为０．７６。
Myotonic dystrophy is due to over-amplification of CTG trinucleotide repeats in the 3 ’non-coding region of the MT-PK gene. Reported in the literature normal CTG copy number of 5 to 35 times, while patients in more than 50 times, and ethnic differences. There is currently no information on the population of our country. To understand the distribution of CTG trinucleotide repeats in Chinese Han population, PCR-PAGE and silver-staining techniques were used to analyze the repeats of 159 Han normals in Chengdu and found that Han and other ethnic groups CTG repeats had different copy number distributions. Of the 318 analyzed chromosomes, 14 alleles were found, of which CTG had the highest frequency of 5 copies (39.3%) and the rest 11 (20) .75%), 12 copies (18.24%), 13 copies (11.32%) and 10 copies (4.09). Alleles with copy numbers greater than 14 were rare, accounting for 4.08% and alleles with copy numbers greater than 19 were fewer, accounting for only 0.94%. In addition, few copies of 6 to 9 alleles, only 6 copies and 8 copies of each of the alleles. A total of 40 cases of homozygotes were found, of which 26 cases were 5/5, 6 cases 11/11, 5 cases 12/12 and 3 cases 13/13, the heterozygosity was 74.8%. The polymorphic information capacity of this system Is 0.76.