PNPO and hyperinsulinemic hypoglycemia, familial, 4: These include pyridox(am)ine-5′-phosphate oxidase (PNPO) deficiency, ALDH7A1 deficiency, PLP-binding protein deficiency, hyperprolinemia type II, hypophosphatasia, and defects in glycosylphosphatidylinositol anchor biosynthesis.2, 3