UGT1A1 and Hyperbilirubinemia: Recent studies in patients who received atazanavir and indinavir established that the proportion of grade 3–4 hyperbilirubinemia was 80% among patients homozygous for the UGT1A1*28 allele, 29% in heterozygous patients and 18% in patients homozygous for the wild-type allele, respectively (Rodríguez-No'voa, S. et al, 2007).