Distribution of Common CYP2C19 Alleles in the Telangana Population of South India: Implications for Pharmacogenomics and Personalized Medicine

Aim and Scope: This study aimed to characterize the distribution of major CYP2C19 alleles (*1, *2, *3, and *17) and their predicted metabolizer phenotypes in a clinical cohort from Telangana, South India, to establish a baseline for regional population pharmacogenomics and personalized medicine. Background: Cytochrome P450 2C19 (CYP2C19) metabolizes clinically vital therapeutics, including antiplatelet agents (clopidogrel) and proton pump inhibitors. Genetic polymorphisms alter enzyme activity, leading to substantial interindividual variation in drug response. Because allele frequencies exhibit geographic heterogeneity, population-specific data are essential for clinical implementation. Materials and Methods: In a retrospective study evaluating 275 individuals in Hyderabad, South India, genomic DNA was extracted from whole blood. Genotyping for CYP2C19*2, *3, and *17 was performed using TaqMan probe-based real-time PCR. Hardy–Weinberg equilibrium (HWE) was assessed using exact and chi-square tests, and diplotypes were mapped to predicted metabolizer phenotypes. Results: Across 550 alleles, the wild-type *1 allele was predominant (65.09%), followed by *2 (18.00%), *17 (16.55%), and *3 (0.36%). Observed genotype distributions complied with HWE (p = 1). Phenotype mapping revealed 45.5% Normal Metabolizers (*1/*1), 36 % Intermediate Metabolizers (*1/*2, *1/*3, *2/*17), 18.18% Rapid Metabolizers (*1/*17), and 0.36% Poor Metabolizers (*2/*2). Conclusion: Over half of the cohort (54.55%) carried actionable non-normal metabolizer phenotypes. The high combined prevalence of intermediate and rapid metabolizers underscores the utility of genotype-guided therapy for antiplatelet and acid-suppressive regimens in regional South Indian clinical practice.