We have carried out molecular-genetic analyses of mononucleotide substitutions at positions 481, 590 and 857 of the arylamine N-acetyltransferase 2 (NAT2) gene to detect the presence or absence of restriction sites for KpnI, TaqI, and BamHI, respectively, in 102 endometriosis patients (average age 35 years) and in 153 healthy women (average age 36.5 years). We found considerable differ­ences in the gene frequency patterns between the two groups. In the endometriosis group, slow acetylators were much more frequent. The allele NAT2*7 prevailed in the endometriosis group (31.1%) vs. 10.4% in the control group [odds ratio (OR) = 3.9], indicating that this allele can be considered as a marker for endometriosis. Rapid acetylators prevailed in the control group (λ² = 4.75; p = 0.029). In the endometriosis group, slow acetylators pre­vailed (43.1%) vs. 10.9% in the control group (λ² = 28.12; p = 0.0005, OR = 6.19), and they were characterized by the presence of more than two slow alleles. While studying the associations of the NAT2 gene genotype with the effectiveness of the therapy, it was found that slow acety­lators prevailed in the group of patients with a positive result.
      Key words: Alleles, Genotypes, Polymerase chain reaction (PCR), Polymorphism, N-acetyltransferase 2 (NAT2)