At present, the use of a quantitative screening tool that informs the relative degree of enzyme activity is the most direct, accessible, and reliable approach, and remains the gold standard for G6PD-deficiency assessment.63 Qualitative tests are also available but only inform whether the person has a certain high level of G6PD in his or her cells. The gene discussed is G6PD; the disease is hyperinsulinemic hypoglycemia, familial, 4.