Examples of Pharmacogenomics Research in Action
- Warfarin - may cause severe, possibly fatal, bleeding complications. Patients with variants CYP2C9 and VKORC1 alleles require lower doses of this oral anticoagulant. Genotyping prior to therapy has been recommended, and large prospective clinical trials are being planned.
- Antidepressants - CYP2D6 and CYP2C19 polymorphisms account for the inter-individual variability in the pharmacokinetics of antidepressants. Increased or decreased enzyme activity leads to increased or decreased metabolism of these drugs.
- Anticancer Drugs - the American Food and Drug Administration (FDA) has approved label changes for anticancer drugs to include pharmacogenetic testing as a means for reducing the rate of severe toxic events, a direct result of pharmacogenomic research.
- Abacavir - causes hypersensitivity in 5% of patients and has shown strong associations with the MHC allele HLA-B*5701. Genotyping prior to this drug’s use has proven cost effective and reduces the incidence of hypersensitivity.
- Lipodystrophy - dependent on promoter region polymorphism (-238) in the TNF-alpha gene, this condition is characterized by fat accumulation, fat atrophy and insulin resistance.
- Breast Cancer - among women with breast cancer treated with tamoxifen, there was an association between CYP2D6 variation and clinical outcomes, such that the presence of 2 functional CYP2D6 alleles was associated with better clinical outcomes and the presence of nonfunctional or reduced-function alleles with worse outcomes.