Продукт гена NAT2 (N-ацетилтрансфераза 2) участвует в биотрансформации и детоксикации ряда ароматических аминов (в частности, 2-аминофлуорена, 4-аминобифенила и 4-нафтиламина), которые являются сильными мутагенами и канцерогенами, а также влияет на метаболизм лекарственных препаратов, ацетилируемых этим ферментом. Разработан биологический микрочип для обнаружения 16 точечных мутаций гена NAT2, сочетания которых определяют 36 аллелей и 660 генотипов гена NAT2. Эти генотипы можно разделить на четыре группы по фенотипу ацетилирования: фенотип “быстрого” (R/R), “промежуточного” (R/S), “медленного” (S/S) ацетилирования и группа, в которой могут быть аллели с фенотипом как промежуточного, так и медленного ацетилирования (R/S или S/S). Группа “R/S или S/S” включает аллели, определяемые сочетанием 7 мутаций (191G/A, 282C/T, 341T/C, 481C/T, 590G/A, 803A/G, 857G/A), цис-транс-положение которых можно установить с помощью рестрикционного анализа. Однозначно определен NAT2-генотип 37 из 71 образца ДНК, а 34 образца охарактеризованы более чем двумя генотипами. По фенотипу ацетилирования в группу “R/S или S/S” из этих 34 образцов ДНК вошли 16, содержащих шесть мутаций: 282C/T, 341T/C, 481C/T, 590G/A и 803A/G. Таким образом, данный биочип позволяет проводить первичный анализ большинства полиморфных замен в гене NAT2.

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.

The NAT2 product, N-acetyltransferase 2, is involved in biotransformation and detoxification of several aromatic amines (in particular, 2-aminofluorene, 4-aminobiphenyl, and 4-naphthylamine), which are strongly mutagenic and carcinogenic, and acetylates some drugs, affecting their metabolism. A biological microchip was developed to detect 16 point mutations, which determine 36 alleles and 660 genotypes of NAT2. The genotypes can be divided into four groups according to the acetylator phenotype: groups with rapid (R/R), intermediate (R/S), or slow (S/S) acetylation and a group combining intermediate and slow alleles ("R/S or S/S"). The last group includes the alleles determined by combinations of seven mutations (191G/A, 282C/T, 341T/C, 481C/T, 590G/A, 803A/G, and 857G/A), whose cis or trans position is detectable by restriction enzyme analysis. The NAT2 genotype was unequivocally established for 37 out of 71 DNA specimens, while the other 34 specimens were characterized by more than two genotypes. By the acetylator phenotype, 16 out of the 34 genotypes were assigned to the group "R/S or S/S," combining mutations 282C/T, 341T/C, 481C/T, 590G/A, and 803A/G. Thus, the biochip allows primary analysis of most NAT2 polymorphic substitutions, the acetylator genotype being important to know in predictive medicine and individualized therapy.

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.

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), transferrin (TF), the third complement component (C′3), group-specific component (GC), and the enzymes, including glycosylase (GLO1), 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 phenotype ee of the Rhesus system 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 ee (RH) in combination with the Le(a-b-) phenotype, representing homozygosity for recessive allele le, was the risk factor for the development of psoriasis.