The prevalence of the GSTM1 null genotype differed within India. The frequency of GSTM1 null in South Indians was significantly lower than that in Caucasians. The frequencies of both GSTM1 and GSTT1 null genotypes in South Indians were significantly lower than in the Japanese.

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To investigate the relationship between CYP2C19 genotypes and the hydroxylation index (HI) of omeprazole in the South Indian population. Healthy unrelated South Indian subjects (n=300) were separated into three groups based on their CYP2C19 genotypes. They were administered a single oral dose of 20 mg omeprazole, and venous blood was collected 3 h later. Plasma was assayed using reversed-phase high-performance liquid chromatography, and the omeprazole HI was calculated. The means of HIs in individuals with CYP2C19*1/*1 (n=124), *1/*2 (n=129) and *2/*2,*2/*3 (n=47) were 2.4, 5.3 and 22.5, respectively, and were found to be significantly different between any two groups (P<0.0001). A good correlation was established between CYP2C19 genotype and omeprazole HI (r=0.54, 95% CI 0.45-0.62; P<0.0001). Of the 300 subjects, 42 (14.0%; 95% CI 10.1-17.9) were phenotypic poor metabolizers (PMs), but only 33 of them had two mutant alleles and the remaining 9 PMs had at least one wild-type allele. Among the 258 extensive metabolizers, 14 had two mutant alleles. The prevalence of PMs in the South Indian population was 14.0%, which is similar to that in North Indians and Orientals but significantly higher than in Caucasians and Africans. A genotype-phenotype relationship was established between the CYP2C19 genotype and HI of omeprazole, but 7.7% of subjects deviated from expected genotype-phenotype associations. This could be due to an additional mutation, either in the exons/introns or in the 5'-regulatory region of the CYP2C19 gene.

Apolipoprotein (ApoAI) is the major protein constituent of high density lipoproteins (HDL). Apolipoprotein (apo) B-100, a component of low density lipoprotein (LDL), serves as a ligand for the removal of LDL from the circulation by the LDL receptor. Genotyping of ApoAI and ApoB polymorphisms was carried out in 185 healthy Tamilian volunteers of south India after clinical examination. Lipid profile was estimated and polymorphisms were detected by the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method. The frequency of the rare M1-, M2- and R- alleles were 21%, 4.3% and 5.4%, respectively. An increase of 9.1 mg dL(-1) (0.23 mmol L(-1)) in HDL-cholesterol (HDL-C) levels was observed with M1-/- genotype when compared to M1+/+ genotype, which was not found after adjustments were made for confounding risk factors. A paradoxical increase in levels of total cholesterol and LDL-cholesterol (LDL-C) was observed with M2+/- genotype when compared to M2+/+ genotype. Analysis of combination of genotypes of ApoAI revealed no influence on the lipid parameters. ApoB EcoRI in contrast to ApoAI polymorphisms had no significant effect on lipid profile..

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