Survey of the genotype for S‐mephenytoin hydroxylase in the Chinese Han population

Abstract

OBJECTIVE: S‐mephenytoin hydroxylase is a polymorphic cytochrome P450 (CYP) enzyme that catalyzes the metabolism of omeprazole, a proton‐pump inhibitor, and some other drugs. The aim of this survey was to investigate the distribution of the genotype of S‐mephenytoin hydroxylase in Chinese people. METHODS: One hundred and fifty‐five unrelated healthy volunteers were selected and their blood samples were used for genotyping by PCR‐restriction enzyme analysis. DNA from homozygous extensive metabolizers (EM) could be digested into two fragments, whereas poor metabolizers (PM) could not be digested and heterozygous EM could be partly digested. RESULTS: Two mutations of CYP2C19 were found; that is, m1 and m2. The frequency of the PM (m/m) genotype was 15.5% (24/155) and that of EM was 84.5% (131/155). The EM included 36.8% (57/155) homo‐EM (wt/wt) and 47.7% (74/155) hetero‐EM (wt/m). CONCLUSIONS: There were two forms of CYP2C19 mutations. The frequency of PM (m/m) and heterozygous EM genotype (w/m) in Chinese people were significantly higher than those of Western white people. Hetero‐EM were more common than homo‐EM in the Chinese population. The genotyping variation might explain the different effect of PPI on individuals.

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