UGT1A1 and Decreased total neutrophil count: One well-known genetic variant is UGT1A1*28, the occurance of neutropenia and CID resulting from elevated SN-38 in response to gene exposure following irinotecan dosing as affected by UGT1A1*6 and UGT1A1*28 allele conditions (Man et al. 2018; Nelson et al. 2021).