ALPL and hypophosphatasia: Both Akp2-deficient mice and patients with severe hypophosphatasia (HPP), a heritable disease due to defective TNAP function, suffer from bone hypomineralization, abnormalities in brain development including hypodensity of the white matter, dilated ventricles, polycystic encephalopathy, atrophy of the hemispheres, and cortical malformations, and also epileptic seizures [28–32].