| Abstract: | Frequencies of hexa- and heptatandem tetrameric repeats in Russian slavonians from the North-Western part of the country were found to be 0.19 and 0.81, respectively, with the frequency of heterozygotes estimated as 0.31. Similar values of allelic frequencies were found for uzbek and azerbaijan populations (0.24 and 0.76; 0.22 and 0.78, respectively). These data assess the existence of genetic equilibrium of both alleles in the populations studied. Hexa TTR is present twice more often in the CF chromosomes than hepta TTR common for normal chromosomes. Absolute genetic disequilibrium of both TTR alleles was observed for CF chromosomes bearing the F508 mutation. The latter was exclusively detected in a conjunction with hexa TTR allele. Combined application of the F508 test and TTR alleles assay significantly increased the number of totally informative CF-high risk families, and thus might be highly beneficial for a subsequent prenatal diagnosis of CF. |
