The antiplatelet agent clopidogrel requires metabolic activation by the CYP2C19 enzyme to exert its effects. Individual responses to this medication are influenced by genetic variants in the CYP2C19 gene. In this study, we systematically examined the distribution of CYP2C19 alleles, genotype patterns, and predicted phenotype categories among cardiovascular disease patients originating from the Yunnan-Guizhou Plateau. These findings are intended to serve as a resource for guiding more personalized therapeutic strategies. Using RT qPCR, we genotyped the CYP2C19*2, *3, and *17 alleles in 1,934 individuals with cardiovascular disease recruited from ten distinct locations across the Yunnan Guizhou Plateau. Patient clinical information was evaluated with chi square tests. In the overall study population, the observed frequencies for CYP2C19 alleles were as follows: *1 at 64.94%, *2 at 29.81%, *3 at 4.42%, and *17 at 0.83%. Nine different genotype combinations were detected, with their respective prevalences being *1/*17 (1.03%), *1/*1 (42.09%), *2/*17 (0.57%), *3/*17 (0.05%), *1/*2 (38.73%), *1/*3 (5.95%), *2/*2 (8.89%), *2/*3 (2.53%), and *3/*3 (0.16%). Based on these genotypes, individuals were classified into four metabolic categories: rapid metabolizers (1.03%), normal metabolizers (42.09%), intermediate metabolizers (45.29%), and poor metabolizers (11.58%). Notable variations in both allele frequencies and phenotype distributions were found across different geographical areas within the region. This study provides the first detailed characterization of CYP2C19 genetic variants among cardiovascular disease patients residing in the Yunnan Guizhou Plateau, serving as an important pharmacogenetic resource for guiding the choice of appropriate therapeutic regimens.
