UGT1A1 and Decreased total neutrophil count: Patients heterozygous for the UGT1A1*28 polymorphism, UGT1A1*1/*28, had significantly higher incidence of leucocytopenia (p = 0.0002), neutropenia (p = 0.0146), thrombocytopenia (p = 0.0032), febrile neutropenia (p = 0.0002), and overall haematologic toxicity (p < 0.00001), than those with UGT1A1*1/*1 and UGT1A1*28/*28 genotype.