Despite this, determination of the genotype of UGT1A1 could have been relevant to contextualise the incidence of diarrhoea and neutropenia, since evidence from the TROPiCS-02 trial has shown that patients homozygous for UGT1A1 *28/*28 had higher rates of grade 3 or 4 diarrhoea and neutropenia than other subgroups [9]. The gene discussed is UGT1A1; the disease is Decreased total neutrophil count.