Familial tumoral calcinosis (FTC)

Familial tumoral calcinosis (FTC) refers to a group of disorders inherited in an autosomal recessive fashion, distinguished by the development of ectopic and vascular calcified masses that occur in settings of hyperphosphatemia (hFTC) and normophosphatemia (nFTC). hFTC is characterized by increased re-absorption of phosphate through the renal proximal tubule, resulting in elevated phosphate concentration and deposition of calcified deposits in cutaneous and subcutaneous tissues, occasionally, in visceral organs. hFTC has been shown to result from mutations in three genes: fibroblast growth factor-23 (FGF23), KL encoding Klotho, and GALNT3, which encodes a glycosyltransferase responsible for FGF23 O-glycosylation; defective function of any one of these three proteins results in hyperphosphatemia and ectopic calcification. nFTC is characterized by absence of metabolic abnormalities. nFTC has been found to be associated with absence of functional SAMD9, a putative tumor suppressor and anti-inflammatory protein.

Inherited metabolic disease

(hFTC) GALNT3 [HSA:2591] [KO:K00710]
(hFTC) FGF23 [HSA:8074] [KO:K04358]
(hFTC) KL [HSA:9365] [KO:K14756]
(nFTC) SAMD9 [HSA:54809]

PMID:19865099 (description, gene)

Sprecher E

Familial tumoral calcinosis: from characterization of a rare phenotype to the pathogenesis of ectopic calcification.

J Invest Dermatol 130:652-60 (2010)

PMID:22142751 (description, gene)

Farrow EG, Imel EA, White KE

Miscellaneous non-inflammatory musculoskeletal conditions. Hyperphosphatemic familial tumoral calcinosis (FGF23, GALNT3 and alphaKlotho).

Best Pract Res Clin Rheumatol 25:735-47 (2011)

PMID:19013236 (description, gene)

Chefetz I, Sprecher E

Familial tumoral calcinosis and the role of O-glycosylation in the maintenance of phosphate homeostasis.

Biochim Biophys Acta 1792:847-52 (2009)