Frequency of cytochrome P450 2C9 mutant alleles in a Korean population

Aims: To determine the frequencies of CYP2C9 variants in the Korean population and compare them with the frequencies in other ethnic populations. Methods: Genotyping of CYP2C9*2 and CYP2C9*3 allelic variants was carried out in 574 Korean subjects by PCR and restriction fragment length pattern analysis. Results: Thirteen of 574 subjects (2.3%) were heterozygous for CYP2C9*3 (Ile₃₅₉Leu), but no subjects with a CYP2C9*2 allele or homozygous for CYP2C9*3 were identified. The allele frequency of CYP2C9*3 in Korean subjects (0.0113, 95% CI 0.0066-0.0193) was similar to that of other East Asian populations, but was considerably lower than that of Caucasian populations. Conclusions: CYP2C9*3 seems to be an allelic variant related to the functional polymorphism of CYP2C9, but this variant is rarely seen among Koreans compared with Caucasians. Routine genotyping of the CYP2C9*2 allele is considered to be unnecessary in Korean and East Asians, because this allele appears to be extremely rare or absent in these populations.