Uncertainty exists whether the 4154delA mutation of the BRCA1 gene detected in unrelated individuals from Latvia, Poland and Russia is a founder mutation with a common ancestral origin. To trace back this problem we analysed the mutation-associated haplotype of the BRCA1 intragenic SNPs as well as intragenic and nearby STR markers in mutation carriers from the aforementioned populations. The mutation-associated SNP alleles were found to be "T-A-A-A-A-G" for six intragenic SNPs of the BRCA1 gene (IVS8-58delT, 3232A/G, 3667A/G, IVS16-68A/G, IVS16-92A/G, IVS18+66G/A, respectively). The alleles 195, 154, 210 and 181 were found to be associated with the 4154delA mutation for STR markers D17S1325, D17S855, D17S1328 and D17S1320, correspondingly. Further analysis of markers in the 4154delA mutation carriers from all three populations allows us to assert that all analysed mutation carriers share a common ancestry.
Our previous research showed that Russian children commit fewer gender-agreement errors with diminutive nouns than with their simplex counterparts. Experiment 1 replicates this finding with Russian children (N = 24, mean 3;7, range 2;10-4;6). Gender agreement was recorded from adjective usage as children described animal pictures given just their names, varying in derivational status (diminutive/ simplex), novelty, and gender. Experiment 2 extends the gender-agreement elicitation methodology developed for Russian to Serbian, a language with similar morphosyntactic structure but considerably fewer diminutives in child-directed speech. Serbian children (N = 22, mean age 3;8, range 3;0-4;1), exhibited an advantage for diminutive nouns of almost the same magnitude as the Russian children. The fact that the diminutive advantage was found in a language with a low frequency of diminutives in the input suggests that morphophonological homogeneity of word clusters and membership in dense neighbourhoods are important factors that contribute to the reduction of inflectional errors during language development.