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

You are here: Pharmacogenetics » Adverse Drug Reactions due to Cytochrome P450 (Overview) » CYP2C19

Cytochrom P450 2C19 (CYP2C19) [T88.7]

OMIM numbers: 609535, 124020 (CYP2C19)

Dipl.-Biol. Birgit Busse

Scientific Background

The enzyme CYP2C19 is involved in the oxidative metabolism of numerous drugs. Among the substrates of CYP2C19 are antidepressants as well as neuroleptics and proton pump inhibitors or clopidogrel. Different genetic variants either lead to a loss, reduction or increase enzyme activity.

CYP2C19*2 is the most frequent allele associated with reduced enzyme activity within the Caucasian population. Approximately 5% of the population are poor metabolizers, while 20% are intermediate metabolizers. Under standard dose of CYP2C19 substrates, both phenotypes may cause adverse drug reactions. In this case, a reduction in dosage may reduce side-effects and thus have a positive impact on the success of treatment. The CYP2C19*17 allele is associated with an increased substrate metabolism and is present in approximately 20% of all Caucasians. Under standard dose, this phenotype frequently does not respond to the medication (non-responder phenotype). Adaptation of the dose may have a positive impact on the success of treatment.