Although the maximum tolerated dose of IRI was confirmed to be 150 mg/m2 for patients with UGT1A1 homozygous (*28/*28, *6/*6, or *28/*6), grade 3 or higher neutropenia was observed in 62.5% of these patients during the first cycle [215]. The gene discussed is UGT1A1; the disease is Decreased total neutrophil count.