UGT1A1 and cancer: In Japanese cancer patients, UGT1A1*28, UGT1A9*1b, UGT1A1*6 (211G > A), and UGT1A1*60 (3279 T > G) are closely associated with the UGT1A9 IVS1 + 399 (I399C > T) polymorphism, and linkage of I399C > T with these variants has been shown to affect irinotecan metabolism [15].