PH1, PH2 and PH3 are caused by mutations in AGXT (encoding the liver-specific peroxisomal enzyme alanine-glyoxylate aminotransferase) [12], GRHPR (encoding the cytosolic and mitochondrial enzyme glyoxylate reductase/hydroxypyruvate reductase expressed in many body tissues but predominantly active in the liver) [13] and HOGA1 (encoding liver- and kidney-predominant mitochondrial 4-hydroxy-2-oxoglutarate aldolase), respectively [14]. This evidence concerns the gene AGXT and primary hyperoxaluria type 1.