[Variation of the parameters of natural reproduction and Crow's indices in the ethnic groups of Dagestan].

Using the 2002 All-Russian population census data, the parameters of differential fertility as a component of natural selection (Crow's indices) have been calculated for women of seven age cohorts of the seven most numerous ethnic groups of the Republic of Dagestan. It has been shown that in the population of Dagestan in the second half of the 20th century the intensities of two types of selection tended to decrease, viz., intragroup selection relaxed in each ethnic group due to considerable reduction of interfamily variance in fertility and intergroup selection relaxed due to reduction ofinterethnic differences in fertility. A reduction of the average number of offspring (kappa) was observed in all ethnic groups, suggesting the spread of birth regulation practices (abortion and contraception). Nevertheless, all Muslim groups (aboriginal Dagestan ethnic groups and Azerbaijanis) are still characterized by an extended pattern of reproduction (2.7 < kappa < 3.3); in Russians kappa = 2.1. Interethnic differentials in natural reproduction rates, along with migration processes, account for the dynamics of the ethnic composition and gene-pool structure of the population of the Republic of Dagestan.

[Mapping genes of major recurrent depression in genetic isolates].

We conducted a genome-wide linkage scan in two extended pedigrees ascertained from two Dagestan genetic isolates (N(o)6007 and 6008) with high aggregation of early onset major depressive disorders (MDD). The first pedigree included in total 22 cases of MDD (15 available) and 11 suicides; the second pedigree contained 29 MDD cases (23 available) and 12 suicides. Five linked regions in our study are consistent with previous findings in association and/or linkage studies with MDD: 11p15, 12q23-24, 13q11-32, 18q22 and 22q11-13. We found two novel for early onset MDD genomic regions with significant linkages in N(o)6007 with Lods = 3.1-3.4 at 2p13.2-p11.2 (and some weak signal in the same region for N(o)6008) and at 14q31.12-q32.13. We also obtained suggestive level linkages at 9q33.3-q34.2 (N(o)6008), 13q31.1-q31.2 (N(o)6007), 11p15 (N(o)6008), 17q25.3 (N(o)6007) and 19q13.31-q13.33 (N(o)6008). Six linked regions (1p36.1-p35.2, 2p13.2-p11.2,13q31, 17q25.3, 18q22 and 22q12.3) were consistent across the two isolates' pedigrees while all other linkage regions (5q14.1-q14.3, 9q33.3-q34.2, 13q31.1-q32.1, 14q31.12-q32.13, 20p13) demonstrated population-specific genetic heterogeneity of MDD. Our results suggest that genetic mapping of complex diseases, including MDD, across genetically homogeneous isolates can enrich the harvest of linkage signals and expedite the search for susceptibility genes.