GRHPR and Pallister-Hall syndrome: According to the defective enzyme (encoded by the corresponding mutated gene) there are different types of PHs, referred to as PH1 (alanine-glyoxylate aminotransferase, AGT) [11], PH2 (glyoxylate/hydroxypyruvate reductase, GRHPR) [12], and PH3 (4-hydroxy-2-oxoglutarate aldolase 1, HOGA1) [13].