Association of Gene Polymorphisms and Serum Levels of ALAS1 with the Risk of Anti‐Tuberculosis Drug‐Induced Liver Injury

The accumulation of protoporphyrin IX in the liver caused by isoniazid and rifampicin through the disorder of heme biosynthesis was considered an important mechanism of anti-tuberculosis drug-induced liver injury (ATLI). Alanine synthase 1 (ALAS1) is a rate-limiting enzyme in the process of heme synthesis. This study aimed to investigate the association between ALAS1 gene polymorphism, serum ALAS1 level, and the risk of ATLI. This study was a case-control study including 58 ATLI cases and 192 controls. Four single nucleotide polymorphisms (SNPs) of the ALAS1 gene were selected for genotyping and serum ALAS1 concentrations were detected using ELISA kits. There was no significant difference in the genotype distribution of four SNPs between the ATLI cases and the controls under different genetic models. Patients carrying the GG genotype of SNP rs352163 in controls had higher baseline ALAS1 levels than those in ATLI cases (243.6 vs 290.2 ng/L, P = .034), and patients with baseline ALAS1 < 337.85 ng/L had a higher risk of ATLI than those with ALAS1 ≥ 337.85 ng/L (HR = 2.679, 95% CI: 1.360-5.278, P = .004). Our findings indicated that the serum ALAS1 concentrations in the ATLI cases were lower than those in the controls, and the lower baseline ALAS1 levels can be associated with higher ATLI risk.