[Identification of functionally significant mutations in NAT2 gene using biological microchips].

The product of gene NAT2 (N-acetyltransferase 2) is involved in the biotransformation system and participates in detoxication of some arylamine derivatives (in particular 2-aminofluorene, 4-aminobiphenyl and 4-naphthylamine) which are strongly mutagenic and carcinogenic. It also renders toxicological and pharmacological influence on a metabolism of medical products metabolized by the enzyme. We developed a microchip for detection of 16 functionally significant mutations coding 36 alleles of gene NAT2. Combinations of these alleles allow us to reveal more than 660 genotypes, which can be divided into four groups according acetylation phenotype: "fast" (R/R), "intermediate" (R/S), "slow" (S/S) and group with average or slow acetylating (R/S or S/S) alleles. The groups "R/S or S/S" include alleles, formed by a combination of 7 mutations (191G/A, 282C/T, 341T/C, 481C/T, 590G/A, 803A/G, 857G/A), theirs cis-trans position can be revealed by restriction analysis. In 37 of 71 DNA samples we unequivocally defined NAT2-genotypes, and other 34 samples have been characterized by more than two genotypes. 16 samples out of 34 had acetylation phenotype of group "R/S or S/S", which is characterized by the following combination of mutations: 282C/T, 341T/C, 481C/T, 590G/A and 803A/G. Thus, the developed biochip is a convenient screening method for primary detection of the majority of polymorphic replacements in gene NAT2.

[Comparative analysis of N-acetylation polymorphism in humans as determined by phenotyping and genotyping].

The N-acetylation polymorphisms of volunteers from the Moscow population analyzed by phenotyping and genotyping have been compared. The ratios between the proportions of fast acetylators (FAs) and slow acetylators (SAs) estimated by phenotyping and genotyping do not differ significantly from each other (47 and 44%, respectively). The absolute acetylation rate widely varies in both FAs and SAs. The NAT2 genotype and allele frequencies in the population sample have been calculated. The most frequent alleles are NAT2*4 (a "fast" allele), NAT2*5, and NAT2*6 ("slow" alleles); the most frequent genotypes are NAT2*5/*5, NAT2*4/*6, and NAT2*4/*5. Comparative analysis of N-acetylation polymorphism estimated by phenotyping and genotyping in the same subjects has shown a complete concordance between the phenotype and genotype in only 62 out of 75 subjects (87%). Comparative characteristics and presumed applications of the two approaches (quantitative estimation of acetylation rate and qualitative determination of the acetylator genotype) to the identification of individual acetylation status are presented.

[Genetic markers and psoriasis in three ethnic populations of Dagestan].

Analysis of clinical material obtained from the individuals (49 psoriasis patients and 357 individuals without this disease) representing three ethnic populations of Dagestan (Avars, Dargins, and Kumyks) was performed. Polymorphism of the blood group loci AB0, Rhesus (RH), Kell, P, and Lewis, as well as of the protein-encoding loci for haptoglobin (HP), group-specific component (GC), and the enzymes, including glycosylase (GL01), esterase D (ESD), 6-phosphate dehydrogenase (6PDG), and acid phosphatase (ACP), was studied. It was demonstrated that in the pooled sample of Avars and Kumyks the Lewis system phenotype Le(a-b-) and the RH homozygotes (ee/ee) were statistically significantly more frequent among the psoriasis patients (P = 0.0488 and P = 0.0166, respectively), than among healthy controls of the same ethnic groups. It was suggested that for the pooled sample of Avars and Kumyks, homozygosity for the recessive RH allele (ee/ee) in combination with the Le(a-b-) phenotype, representing homozygosity for recessive allele le, was the risk factor for the development of psoriasis.