[Genetic epidemiological study of monogenic hereditary diseases in the Republic of Tatarstan: population dynamic factors determining the differentiation of the load of hereditary diseases in five districts].

A genetic epidemiological study has been performed in five districts of the Republic of Tatarstan, Russia: Arsky, Atninsky, Kukmorsky, Buinsky and Drozhzhanovsky raions. The total size of the population surveyed is 188 397 people. Tatars accounted for 77.13% of the population analyzed (145466 people) and were represented by two main ethnic groups: Kazan Tatars and Mishars. The medical genetic study encompassed the total population of the districts, irrespective of ethnicity, and was carried out according to the standard protocol developed in the Laboratory of Genetic Epidemiology of the Research Center for Medical Genetics of the Russian Academy of Medical Sciences. After segregation analysis, the prevalence rates of the main types of monogenic hereditary disorders (MHDs), i.e., autosomal dominant (AD), autosomal recessive (AR), and X-linked diseases, have been calculated for the total population of the five districts and for Tatars alone. The prevalence rates ofAD, AR, and X-linked diseases considerably vary in different subpopulations. The largest difference in the MHD prevalence rate has been found between the rural and urban populations. The overall prevalence rate of MHDs was one patient per 293 urban residents and populations and one patient per 134 rural residents, with a wide variation between subpopulations, from 1 : 83 people in the rural population of Atninsky raion to 1: 351 people in the town of Kukmor. Comparison of the MHD prevalence rate in Tatars with those in populations surveyed earlier has shown that the characteristics of the load of MHDs in the Tatar population are similar to those in some districts of the republics of Bashkortostan, Udmurtia, Mari El, and Chuvachia. In Russian populations of European Russia, the MHD prevalence rates are substantially lower. Correlation analysis has shown high (r = 0.5-0.9) significant correlations between the local inbreeding (a), the im index, the random inbreeding (F(ST)), and the AD and AR prevalence rates in the Tatar population. This analysis has demonstrated that genetic drift is the main population dynamic factor determining the MHD load in the Tatar population.

[Endogamy and isolation by distance in the Tatarstan population].

A total sample of 31 837 marriage records made in 13 raions (districts) of Tatarstan in 1990-2000 have been used to determine the endogamy index and parameters of Malecot's isolation by distance model. The endogamy index varied from 0.45 in Pestrechinsky raion to 0.74 in Aktynashsky raion. The parameters of Malecot's isolation by distance model varied in Tatars as follows: random inbreeding, from 0.00014 to 0.00076; root mean square migration, from 46 to 110 km.

[Ethnically assortative marriage in the rural population of Tatarstan].

Ethnically assortative marriage rates have been calculated for Tatars (1.16) and Russians (8.37) on the basis of 14729 marriage records made in 1990-2000 in seven raions of Tatarstan (Arsky, Atninsky, Drozhzhanovsky, Alkeevsky, Musljumovsky, Aktanyshsky, and Baltasinsky). The outbreeding rate of Tatars (5.35%) has been found to be lower than in a number of other populations studied in this respect.