Retrospective analysis of a phase I/II clinical trial of nilotinib in patients with BCR-ABL positive CML or acute lymphoblastic leukemia (ALL) found that UGT1A1*28 homozygotes had a significant risk of grade 3/4 hyperbilirubinemia [28]. Here, ABL1 is linked to chronic myelogenous leukemia, BCR-ABL1 positive.