To investigate the physiopathology of PH and perform proof of concept studies that might lead to novel therapies, we cloned the mouse Agxt gene [198] and used standard gene targeting via homologous recombination in ES cells to generate an AgxtKO mouse model [20] that reproduced the main features of PH1, although with a milder phenotype than most human patients. Here, AGXT is linked to primary hyperoxaluria type 1.