While the hypophosphatemic rickets phenotypes of 2.3 kb Col 1a1-Cre;Fam20Cflox/flox mice, to a certain degree, resembled those of the Sox-Cre;Fam20Cflox/flox mice in which Fam20C was inactivated in nearly all the tissues, the general health of the former was better than the later. Here, FAM20C is linked to rickets.