X-linked hypophosphatemic rickets is the most common familial form of rickets and is characterized by hypophosphatemia associated to hyperphosphaturia and abnormal 1,25-dihydroxyvitamin D metabolism. There are several other forms of hereditary hyperphosphaturias, which may indicate the complexity of phosphate homeostasis. As the basic damage has not been defined, its physiology comprehension is still unclear. Recently, using the positional cloning method, a strong candidate gene was identified: the PEX gene (Phosphate-regulating gene homologies to Endopeptidases on the X-chromosome), which seems to be the responsible for the disease. Many types of mutations in PEX were found in more than 60 families. The recent genetic advances in the study of this disease have allowed a much better understanding of its physiopathology.
Rickets; Hypophosphatemia; Hyperphosphaturia; PEX gene