G6PD and hyperinsulinemic hypoglycemia, familial, 4: Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common human enzyme disorder [Cappellini and Fiorelli, 2008], found throughout malarious regions, with an estimated overall allele frequency of 8.0% (50% uncertainty interval: 7.4%–8.8%) across malaria endemic countries [Howes et al., 2012].