A haplotype including UGT1A1*6 and UGT1A7*3, noted in as many as 15% of Japanese patients, and UGT1A1*6 homozygosity, noted in 7% of Korean patients, were significantly associated with decreased glucuronosyltransferase activity for SN-38 and severe neutropenia (Han et al, 2006; Fujita et al, 2007). This evidence concerns the gene UGT1A1 and Decreased total neutrophil count.