Polymorphism of the (CTG)n Repeat of the Myotonin Protein Kinase Gene in Populations of the Sakha Republic (Yakutia) and Central Asia

The allele frequency distribution of the (CTG)n repeat located in the 3′-terminal region of the myotonin protein kinase gene (DMPK) was compared for populations of Yakutia (three ethnogeographic groups of Yakuts, Evenks, Evens, Yukaghirs, and Dolgans) and Central Asia (Kazakhs, Uzbeks, and Uighurs) and other ethnic groups. The populations of the two regions proved to considerably differ from each other: features characteristic of Asian Mongoloids were more distinct in the populations of Yakutia, while the Central Asian populations were closer to European populations. The (CTG)n allele spectrum of Yakuts was considered in connection with the high incidence of myotonic dystrophy in Yakutia. The results support the hypothesis of the founder effect for the spread of myotonic dystrophy in Yakuts. Data on the (CTG)n polymorphism were used to estimate the phylogenetic relationships of the populations under study.