SLC35A2 and obesity due to melanocortin 4 receptor deficiency: UDP-glucuronosyltransferase nomenclature is similar to that of the CYPs, with the UGT1 and UGT2 subfamilies being the most relevant for drug metabolism (Mackenzie et al., 2005).6 UDP-glucuronosyltransferase activity is influenced by factors including cigarette smoking, obesity, age, and gender (Liston et al., 2001).