Limited frequency of the CYP2C19*17 allele and its minor role in a Japanese population

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT
• A 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 ADDS
• In 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.  

AIMS

We investigated the CYP2C19 * 17 allelic frequency in Japanese subjects, and evaluated whether CYP2C19 * 17 is an important determinant of interindividual variability of CYP2C19 activity.  

METHODS

We enrolled 265 subjects to determine their CYP2C19 genotype and plasma metabolic ratio following a single dose of 40 mg omeprazole.  

RESULTS

Seven 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.  

CONCLUSIONS

The low frequency of CYP2C19 * 17 and the absence of * 17/ * 17 indicates that CYP2C19 * 17 plays a minor role in the Japanese population.