Lightwood syndrome revisited with a novel mutation in CYP24 and vitamin D supplement recommendations.

A novel mutation in CYP24A1 provides insight into idiopathic infantile hypercalcemia. In this report of 3 brothers, in twins supplemented with vitamin D (1900 IU/d), only the twin homozygous for CYP24A1 exhibited idiopathic infantile hypercalcemia. A subsequently affected younger brother given vitamin D 400 IU/d was not hypercalcemic.