What is familial hyperphosphatemic tumoral calcinosis?
Familial hyperphosphatemic tumoral calcinosis results from inactivating mutations of the gene that encodes FGF 23. FGF 23 normally acts through the FGF 23 receptor and coreceptor Klotho to regulate (lower) serum phosphorus by enhancing renal phosphate loss and reducing intestinal phosphate absorption by lowering serum 1,25 (OH) 2 vitamin D levels through inhibition of renal 1-alpha-hydroxylase. Patients with this condition make insufficient amounts of functional FGF 23 and, consequently, develop painful ectopic calcifications and elevated serum phosphorus levels.
