PH1 (OMIM # 259900) represents the most common and severe type of primary hyperoxalurias, caused by mutations in the AGXT gene encoding the liver peroxisomal enzyme alanine:glyoxylate aminotransferase (AGT; EC 2.6.1.44) [2, 3]. The gene discussed is AGXT; the disease is primary hyperoxaluria type 1.