Hereditary vitamin D resistant rickets (HVDRR) case series: phenotype, genotype, conventional treatment, and adjunctive cinacalcet therapy.

Introduction: Hereditary vitamin D resistant rickets (HVDRR) is a rare autosomal recessive disorder marked by end-organ resistance of 1,25-dihydroxyvitamin D secondary to various mutations in the vitamin D receptor gene. The currently accepted treatment modality involves bypassing the affected receptors in the gut with high-dose intravenous calcium. In a few limited case reports, cinacalcet, a calcimimetic, has been used as an adjunctive therapy.