[Analysis of the association of HLA-DQ1 alleles with mutation of the 21-hydroxylase gene in patients with congenital adrenal hyperplasia]. / Analiz assotsiatsii allelei HLA-DQA1 s mutatsiiami gena 21-gidroksilazy u bol'nykh s vrozhdenno i giperplaziei kory nadpochechnikov.

In 96 patients with congenital adrenal hyperplasia (CAH) and 50 healthy donors from northwestern Russia the distribution of the HLA-DQA1 alleles and the mutation spectrum and frequency at the CYP21B gene were examined. In the patients with nonclassical (NC) CAH, the distribution of the HLA-DQA1 polymorphic alleles was similar to that in the population sample. In the patients with the salt-wasting form of the disease a statistically significant decrease of the *0401 or *501 major allele frequency was observed. The prevalence of certain HLA-DQA1 genotypes, namely, HLA5, HLA3, and HLA4, was observed in the patients with the NC, salt-wasting (SW), and simple virilizing CAH, respectively. Each clinical group was characterized by a specific spectrum of clinically valuable mutations. An association between the CYP21B mutations most frequently found in case of SW and SV CAH (delB, I2splice, and I172N) and certain HLA-DQA1 alleles was demonstrated. The necessity of more precise clinical diagnostics of the NC CAH cases along with detailed examination of this group for determination of the major mutations typical of the NC CAH cases from northwestern Russia is discussed.

[Analysis of the spectra of mutational damage of the 21-hydroxylase gene in patients with adreno-genital syndrome]. / Analiz spektra mutatsionnykh povrezhdenii gena 21-gidroksilazy u bol'nyh s adrenogenital'nym sindromom.

The spectrum of mutations in the steroid 21-hydroxylase gene (CYP21B) and the frequency of 11 mutations among 66 patients with different forms of congenital adrenal hyperplasia (CAH) were analyzed by means of PCR amplification. Each of the CAH forms was characterized by specific spectrum of diagnostically important mutations. The salt-losing (SL) form of the disease was most frequently associated with gene deletion (39%) and the 668-13C-G mutation in the second intron (23.5%), whereas the majority of simple virilizing (SV) CAH cases were associated with the 1172N mutation in exon 4 (22%), gene deletion (16.5%), and the 668-13C-G mutation (16.5%). Mutations in the steroid 21-hydroxylase gene were detected in 70% of the chromosomes from the patients with the SL and SV forms of CAH, and only in 1.3% of the chromosomes from the patients with the nonclassic (NC) form. A total of 78 mutant chromosomes from the NC CAH patients were examined, and only one case of a gene deletion in the heterozygous state was revealed. In the individuals examined, the V281L and P30L mutations described in the NC CAH patients from other populations were not detected. This result can be explained either by the fact that NC CAH cases in Russia are associated with other major mutations, or by difficult clinical diagnosis questionable CAH cases.

[Molecular-genetic analysis of tandem repeats in intron 6B of the CFTR gene in various populations and in cystic fibrosis patients]. / Molekuliarno-geneticheskii analiz tandemnykh povtorov v introne 6B gena TRBM v nekotorykh populiatsiiakh i u bol'nykh mukovistsidozom.

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.