中国汉族人强直性肌营养不良基因CTG重复序列多态性的初步研究  

POLYMORPHISM OF CTG TRINUCLEOTIDE REPEATS OF MYOTONIC DYSTROPHY GENE IN CHINESE POPULATION

作　　者：潘阿根[1] 张思仲[1] 

机构地区：[1]华西医科大学医学遗传研究室

出　　处：《中华医学遗传学杂志》1996年第3期138-142,共5页Chinese Journal of Medical Genetics

基　　金：国家自然科学基金

摘　　要：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 associated with an increased number of CTG repeats in the 3' untranslated region of the myotonin protein kinase gene(MT-PK) located on chromosome 19q13.3. Using polymerase chain reaction the triplet repeats region of the gene of 159 normal subjects from Chengdu area was analyzed. A total of 14 alleles were found ranging in size from 5 to 29 copies with the most common allele of 5 repeats(39.31%). The other major alleles were in the range of 10 to 13 repeats(54.40% In total, including 20.75% of 11,18.24% of 12,11.32% of 13 and 4.09% of 10 repeats respectively). Only two chromosomes were observed with repeats 6,7,8 and 9. It is remarkable that only 13 alleles were found to be longer than 14 repeats(4.08%) and 3 alleles longer than 19 repeats(0.94%).The results suggest that the lower prevalence of DM in China may partly be related to the lower frequency of high number of CTG repeats. Heterozygote frequency in this population was 74. 8%.The CTG repeat is very informative with a PIC value of 0.76.

关 键 词：汉族 强直性 肌营养不良 三核苷酸 多态现象 

分 类 号：R746.202[医药卫生—神经病学与精神病学]