Center for Human Genetics and Laboratory Diagnostics, Dr. Klein, Dr. Rost and Colleagues

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Cytochrome P450 2C9 (CYP2C9) [T88.7]

OMIM number: 601130 (CYP2C9)

Dipl.-Biol. Birgit Busse

Scientific Background

CYP2C9 is involved in the metabolism of various drugs. Important substrates of CYP2C9 include NSAIDs, antidiabetic drugs, coumarin derivatives or phenytoin.

Variants in the CYP2C9 gene are associated with reduced enzyme activity, whereby the presence of the alleles CYP2C9*2 and CYP2C9*3 represents the most common genetic cause for enzyme deficiency. Among all Caucasians, approximately 4% are poor metabolizers, while 30% are intermediate metabolizers. Under the standard dose of CYP2C9 substrates, both phenotypes may cause adverse drug reactions. In this case, a reduction in dosage may have a positive impact on the success of treatment.