UGT1A1 and neutropenia: Moreover, Guangxi Zhuang patients with UGT1A1*6 mutations had a higher risk of 3~4 grade delayed-onset diarrhea after receiving irinotecan (45% vs. 9.1%, p = 0.001), and an increased risk of 3~4 grade neutropenia (40% vs. 15.2%, p = 0.017), which was consistent with numerous clinical studies in Japan [23–25].