Aside from the star-alleles of the Cytochrome P450 family which are responsible for phase 1 of drug metabolism, we also identify a number of variants located on the genes encoding phase 2 enzymes, such as UGT1A1 (rs4148323 with AF of 10.5%), UGT1A3 (rs45625338 with AF of 2.3%, rs45449995 with AF of 1.4%) and UGT2B10 (rs1976666 with AF of 7.5%). The gene discussed is UGT1A1; the disease is atrial fibrillation.