After adjusting for age, gender, BMI, drinking status, smoking status, and the timing of blood collection, a decrease in NAT2 demethylation index observed within 1–7 days of treatment was found to be independently associated with higher serum levels of ALT and AST measured 8–60 days after starting treatment in tuberculosis patients (β-coefficient = − 0.005; 95% CI − 0.007, − 0.002; P < 0.001; β-coefficient = − 0.002; 95% CI − 0.003, − 0.001; P = 0.005, respectively). This evidence concerns the gene GPT and tuberculosis.