GSTM1 and G6PD deficiency: The performance of the CareStartTM G6PD in identifying G6PD deficiency at 30% assay-specific G6PD activity cut-off (0.77) U/g Hb is shown in Table 2 with 63% sensitivity, 95% specificity, 57% positive predictive value, 96% negative predictive value, and 92% accuracy.