A meta-analysis demonstrated a significant increase in grade 3/4 neutropenia for UGT1A1 *28/*28 patients at medium (150–250 mg/m2) (OR 3.22, p = 0.008) and high doses (>250 mg/m2) (OR 27.8, p = 0.005) [93]. This evidence concerns the gene UGT1A1 and Decreased total neutrophil count.