HYPERPHOSPHATEMIC FAMILIAL TUMORAL CALCINOSIS

Familial tumoral calcinosis (FTC) is a severe metabolic disorder characterised by the progressive deposition of calcified masses in cutaneous and subcutaneous tissues, which results in painful ulcerative lesions with severe skin and bone infections. Patients may also have dental abnormalities, vascular calcifications, cortical hyperostosis and angioid streaks of the retina. Two types of FTC have been recognised, hyperphosphatemic FTC (HFTC) and normophosphatemic FTC (NFTC).

HFTC is an autosomal recessive disorder caused by loss of function variants in the GALNT3 gene (Topaz et al 2004 Nat Genet 36, 579-581) and the FGF23 gene (Benet-Pages et al. Hum Mol Genet. 2005 14:385-390). HFTC with hyperparathyroidism and carotid artery calcifications has been reported in a patient with a homozygous variant in the KL gene (Ichikawa et al 2007 J Clin Invest 117, 2684-269).

Autosomal recessive variants in the SAMD9 gene are reported to cause NFTC (Topaz et al 2006 Am J Hum Genet 79(4):759-64)

The laboratory participates in the European Molecular Genetics Quality Network (EMQN) sequencing scheme.