• Katsuyoshi Sugimoto, Tsukasa Uno, Hiroshi Yamazaki, and Tomonori Tateishi.
• Department of Clinical Pharmacology, Hirosaki University School of Medicine, Hirosaki, Aomori 036-8562, Japan.
• Br J Clin Pharmacol. 2008 Mar 1; 65 (3): 437-9.

What Is Already Known About This SubjectA novel CYP2C19 gene variant, CYP2C19*17, is associated with increased metabolic activity. Ethnic differences in the frequency of the variant allele have been reported. However, the frequency of the CYP2C19*17 allele has not been studied in the Japanese population.What This Study AddsIn a population of 265 healthy Japanese subjects, a low frequency (1.3%) of the CYP2C19*17 allele was observed. The limited frequency of the *17 allele and the absence of a subject homozygous for *17 indicated that CYP2C19*17 would play a minor role in a Japanese population.AimsWe investigated the CYP2C19*17 allelic frequency in Japanese subjects, and evaluated whether CYP2C19*17 is an important determinant of interindividual variability of CYP2C19 activity.MethodsWe enrolled 265 subjects to determine their CYP2C19 genotype and plasma metabolic ratio following a single dose of 40 mg omeprazole.ResultsSeven subjects heterozygous for CYP2C19*17 and no *17/*17 subjects resulted in the CYP2C19*17 frequency being 1.3%. These heterozygotes had moderate metabolic activities when compared with the metabolic ratio of the other subjects.ConclusionsThe low frequency of CYP2C19*17 and the absence of *17/*17 indicates that CYP2C19*17 plays a minor role in the Japanese population.

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