N-acetyltransferase and cytochrome P450 2E1 gene polymorphisms and susceptibility to antituberculosis drug hepatotoxicity in an Indian population.

Background. Antituberculosis drug hepatotoxicity (ATDH) is common in India. Isoniazid, a constituent of most anti- tuberculosis drug regimens, is metabolized by N-acetyltransferase (NAT2) and cytochrome P450 2E1 (CYP2E1) enzymes. We therefore studied the association of some single-nucleotide polymorphisms (SNPs) in these enzyme genes with ATDH. Methods. Allelic and genotypic frequencies at three SNP loci in the NAT2 gene (rs1799929, rs1799930 and rs1799931) and one locus (rs2031920) in the CYP2E1 gene were studied using restriction fragment length polymorphism in 33 patients who developed ATDH following an isoniazid- containing antituberculosis drug regimen and 173 healthy blood donors. After confirming adherence of the control data to the Hardy-Weinberg equilibrium model, genotype and allele frequencies in the two groups were compared. Results. For SNP rs1799930 in the NAT2 gene, 7 (21%), 21 (64%) and 5 (15%) patients, and 93 (54%), 62 (36%) and 18 (10%) controls had GG, GA and AA genotypes, respectively (p=0.003; odds ratio [OR] for GA v. GG=4.50 [95% CI 1.80-11.22] and for AA v. GG=3.69 [1.05-12.93]). Allele frequency for G nucleotides for this SNP was 0.53 among patients and 0.72 among controls (OR 2.24 [1.31-3.84], p=0.007). The allele and genotype frequencies of the other NAT2 SNPs and the CYP2E1 SNP showed no significant difference between cases and controls. All the 33 patients and 151 (87%) of 173 controls had mutant allele at one or more of the three NAT2 SNP loci (p=0.03). The presence of two or more mutant alleles, a marker of slow acetylator status, was more frequent in patients (23/33 [70%]) than in controls (73/173 [42%]; OR 3.23 [95% CI 1.45-7.19], p=0.004). Conclusion. In India, the risk of ATDH is increased in persons with 'A' allele at SNP rs1799930 in the NAT2 gene, but is not associated with rs2031920 polymorphism in the CYP2E1 gene.

Non-organ-specific autoantibodies in Indian patients with chronic liver disease.

BACKGROUND: Autoantibody testing is used to diagnose autoimmune hepatitis (AIH), a cause of chronic liver disease (CLD). However, various autoantibodies are often detectable in patients with CLD due to other causes too. Since data on autoantibody prevalence in Indian patients with CLD are limited, we decided to undertake the current study. METHODS: Patients with CLD with a known cause other than AIH and a separate group of patients with CLD in whom no cause could be identified were studied. Indirect immunofluorescence assays were used to detect anti-nuclear antibodies (ANA), anti-smooth muscle antibodies (ASMA) and anti-liver-kidney microsomal antibodies (anti-LKM). Serum dilutions tested were 1:80 for ANA and 1:40 for other autoantibodies. RESULTS: Of the 175 patients with CLD of a known cause, 69 (39 %) had one or more autoantibodies, including ANA in 35 (20 %) patients and ASMA in 44 (25 %) patients. None had anti-LKM. The prevalence rates of any autoantibody, ANA and ASMA were similar in patients with CLD due to alcohol (34 %, 20 %, and 24 %, respectively), HCV infection (43 %, 20 %, and 26 %) and HBV infection (40 %, 18 %, and 25 %). The most common ANA pattern observed was speckled (29/35 patients), followed by nucleolar (5/35) and homogeneous (1/35). The ASMA titers did not exceed 1:80. The antibody prevalence rates were similar in patients with liver cirrhosis and chronic hepatitis, and in those with different disease severity. Serum IgG levels were similar in patients with and without detectable autoantibodies. Patients with no known cause of CLD (n = 50) had similar prevalence rates of autoantibodies, ANA or ASMA. CONCLUSION: Autoantibodies were detected in a large proportion of patients with CLD, both cryptogenic and with known cause. Detection of autoantibodies in CLD does not necessarily indicate a diagnosis of AIH, and presence of homogenous pattern of ANA may be more relevant. Indiscriminate testing for autoantibodies in patients with CLD, especially those with a known cause, may not be warranted.