Familial occurrence of idiopathic infantile hypercalcemia

Idiopathic infantile hypercalcemia (IIH) is a rare cause of hypercalcemia i n the Ist year of life and was initially considered part of a spectrum enco mpassing vitamin D intoxication, Williams syndrome, and idiopathic hypercal cemia. Identification of the gene for Williams syndrome now allows a clear separation of IIH from Williams syndrome. The inheritance and pathogenesis of IIH remains largely unknown, with only sporadic cases reported to date. This report describes a family with two siblings with IIH. The pedigree is consistent with autosomal recessive inheritance, but more complex inheritan ce is suggested by the occurrence of hypercalciuria in a number of family m embers. Although one affected patient demonstrated elevated 1,25-dihydroxyv itamin D-3 levels, no conclusions regarding the pathogenesis of this condit ion could be drawn.