N-acetyl transferase 2 polymorphism and advanced stages of endometriosis in South Indian women.

Aylamine-N-acetyl transferase is a phase II detoxification enzyme encoded by the gene NAT2. Single nucleotide polymorphism (SNP) changes from the wild type NAT2 *4 allele result in allelic variants *5, *6 and *7. Homozygotes for the NAT2 *4 wild type are fast acetylators; heterozygotes with one wild-type allele and a variant NAT2 *5, *6 or *7 allele have reduced enzyme activity and individuals with two variant alleles are slow acetylators. Previous studies have implicated NAT2 as a susceptibility factor in endometriosis. This study investigated the NAT2 allele frequencies and genotype distributions in 252 unrelated women with endometriosis and 264 controls of South Indian origin. No differences were found between the frequencies of fast and slow acetylators in cases (34.9% and 65.1%) and controls (33.3% and 66.7%). Two NAT2 genotypes *7/*7 (1.2%) and *5/*6/*7 (1.6%) were detected in endometriosis cases only. Four new combinations, 6D (481 + 590 mutation), 7C (590 + 857), 7D (590 + 803 + 857) and 7E (481 + 590 + 803 + 857) were detected, which have not been reported earlier. Similar genotype and phenotype results were obtained in 33 affected sister-pairs. The case-control data from this study suggest there is no association between endometriosis and NAT2 in South Indian women; however, two new variant genotypes and seven SNP combinations were also identified in cases only, which suggests that the gene may still have some as yet undetermined role in the disease.