Vitamin D-resistant rickets: from clinical examination to genetic investigation. "A round trip"

Key words: Genetic mutation, Terminology of rickets, Vitamin D, Vitamin D-resistant rickets

The term “vitamin D-resistant rickets” was used to describe a clinical condition which was indistinguishable from the common rickets except that the signs occurred in spite of adequate vitamin D treatment. Recent studies showed that vitamin D-resistant rickets is due to genetic mutations of some enzymes involved in vitamin D activation, metabolism or action. This may explain why vitamin D treatment is not able to cure patients affected by these forms of rickets. Indeed, vitamin D metabolites (calcitriol, alfacalcidol) associated with calcium or phosphate salts according to the pathogenesis of the disease are the most effective treatments for patients affected by rickets due to genetic mutations. The evidence of a genetic mutation in a patient with rickets is crucial not only for a correct diagnosis and treatment, but also for prognosis.