Variants in the gene encoding alanine-glyoxylate aminotransferase (AGXT) are responsible for type I primary hyperoxaluria (PH1; OMIM 259900), type II (PH2; OMIM 260000) is caused by variants in the glyoxylate reductase/hydroxypyruvate reductase gene (GRHPR), and type III (PH3; OMIM 613616) is caused by variants in the mitochondrial dihydrodipicolinate synthase-like gene (HOGA1). The gene discussed is GRHPR; the disease is primary hyperoxaluria type 1.