CYP2B6

CYP2B6 is a gene of the Cytochrome P450 superfamily of enzymes. The enzymes are involved in the metabolism of xenobiotics in the body. The CYP2B6 gene is expressed in the liver and its expression is inducible by phenobarbital. The gene is located on chromosome 19 in a cluster with two closely related genes that encode enzymes with distinct substrate specificities. This gene is oriented in a head-to-tail configuration with the gene for cytochrome P450 CYP2A7, with the coding regions being separated by approximately 20 kb.

Function

The CYP2B6 enzyme is involved in the metabolism of several clinically important drugs including bupropion, efavirenz, and methadone. It is also involved in the metabolism of several carcinogens including 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), a tobacco-specific nitrosamine, and aflatoxin B1.

Polymorphism

There is a high degree of polymorphism in the CYP2B6 gene, with more than 100 variants identified. These variants can have a significant impact on the metabolism of drugs and other xenobiotics. For example, the CYP2B6*6 allele is associated with decreased metabolism of efavirenz, a drug used in the treatment of HIV.

Clinical significance

The CYP2B6 enzyme is involved in the metabolism of several drugs that are used in the treatment of a variety of diseases. Variations in the CYP2B6 gene can affect the metabolism of these drugs, potentially leading to altered drug efficacy or toxicity. For example, individuals with the CYP2B6*6 allele may require a lower dose of efavirenz to avoid side effects.

See also

• Cytochrome P450
• Pharmacogenomics