A total of 4 of 9 (44%) patients with a positive fluorescent screening test denoting G6PD deficiency had a normal G6PD genotype, indicating suboptimal specificity of the test, which could be related to the presence of additional sources of oxidative stress (eg, deriving from food or drugs) not accounted for in the test. The gene discussed is G6PD; the disease is G6PD deficiency.