Prevalence of anaemia was not significantly different between CYP2D6 status on days 3 (x2 = 0.170, p = 0.747) and day 7 (x2 = 1.456, p = 0.228), but was significantly different between G6PD status with higher prevalence occurring in G6PD normal patients on day 3 (93.1% (108/116), trend x2 = 6.136, p = 0.047) and in G6PD deficient patients (100% (20/20), trend x2 = 7.994, p = 0.018) on day 7. The gene discussed is G6PD; the disease is anemia (phenotype).