Pharmacogenomics is the study of the role of the genome in drug response. Its name reflects its combining of pharmacology and genomics. Pharmacogenomics analyzes how the genetic makeup of an individual affects his/her response to drugs. One current use of pharmacogenomics involves people infected with the human immunodeficiency virus (HIV). Before prescribing the antiviral drug abacavir, doctors now routinely test HIV-infected patients for a genetic variant that makes them more likely to have a bad reaction to the drug.