Other very rare causes of pyridoxine-dependent epileptic encephalopathies are hypophosphatasia due to tissue nonspecific alkaline phosphatase (TNSALP) deficiency, mutation in phosphatidylinositol glycan anchor biosynthesis class V (PIGV) causing hyperphosphatasia, and hyperprolinemia type II secondary to pyrroline 5-carboxylate (P5CD) deficiency [37]. This evidence concerns the gene ALPL and hyperinsulinemic hypoglycemia, familial, 4.