NAT2 6A, a haplotype of the N-acetyltransferase 2 gene, is an important biomarker for risk of anti-tuberculosis drug-induced hepatotoxicity in Japanese patients with tuberculosis.

Aim: To investigate an association between N-acetyltransferase 2 (NAT2)-haplotypes/diplotypes and adverse effects in Japanese pulmonary tuberculosis patients.

Methods: We studied 100 patients with pulmonary TB treated with anti-TB drugs including INH. The frequencies and distributions of single nucleotide polymorphisms, haplotypes, and diplotypes of NAT2 were determined by the PCR-restriction fragment length polymorphism method, and the results were compared between TB patients with and without adverse effect, using multivariate logistic regression analysis.

Results: Statistical analysis revealed that the frequency of a variant haplotype, NAT2 6A, was significantly increased in TB patients with hepatotoxicity, compared with those without hepatotoxicity [P = 0.001, odds ratio (OR) = 3.535]. By contrast, the frequency of a wild-type (major) haplotype, "NAT2 4", was significantly lower in TB patients with hepatotoxicity than those without hepatotoxicity (P < 0.001, OR = 0.265). There was no association between NAT2-haplotypes and skin rash or eosinophilia.

Conclusion: The present study shows that NAT2 is one of the determinants of anti-TB drug-induced hepatotoxicity. Moreover, the haplotypes, NAT2 4 and NAT2 6A, are useful new biomarkers for predicting anti-TB drug-induced hepatotoxicity.