Multivariate logistic regression analysis was then used to confirm the significant association between the presence of the homozygous variant UGT1A1 genotype (*6/*28 or *6/*6) and the risk of G4 neutropenia (P=0.029; odds ratio, 6.90; 95% confidence interval, 1.22–38.99). The gene discussed is UGT1A1; the disease is neutropenia.