The first case reports of HCINF1 were published in the 1950s, when approximately 200 cases of PTH-independent hypercalcaemia in infants were noted in the United Kingdom because of the wide use of formula milk enriched with increased doses of vitamin D (up to 4000 International Units (IU)) (14, 15). Here, CYP24A1 is linked to Hypercalcemia.