SLC35A2 and Hyperbilirubinemia: Consistent with ATV inhibition of uridine 5’-diphospho-glucuronosyltransferase (UGT),20 the enzyme responsible for bilirubin glucuronidation, hyperbilirubinemia was reported as a clinical or Grade 3–4 laboratory event (total bilirubin elevation > 2.5 x upper limit of normal) in 29.4% and 37.8% of patients, respectively.