Patients with severe G6PD deficiency had significantly decreased G6PD activity (1.11 ± 0.90) compared to normal controls (15.96 ± 3.03; P < 0.001), while the G6PD activity of those with moderate G6PD deficiency (8.63 ± 0.67) did not significantly differ compared to normal controls. Here, G6PD is linked to G6PD deficiency.