Clinical Guidance

No genotype-phenotype correlations are known.

• Sibs with the same GALNT3 pathogenic variants have been reported to have markedly different clinical courses .

• Treatment response does not appear to vary by genotype.

Source: GeneReviews — "Hyperphosphatemic Familial Tumoral Calcinosis"

Diagnostic Criteria

Suggestive Findings

Hyperphosphatemic familial tumoral calcinosis (HFTC) should be suspected in individuals with the following clinical, laboratory, and/or imaging findings.

Clinical Findings

Tumoral calcinosis or ectopic calcifications are typically seen in periarticular soft tissues exposed to repetitive trauma or prolonged pressure, such as the hips, elbows, and shoulders; they can also be observed in other locations ranging from the eyelid to the submucosa of the large intestines . Hyperostosis. Some affected individuals experience transient but recurrent episodes of pain in the long bones, typically the tibia, associated with erythema, edema, and warmth of the overlying skin .

Source: GeneReviews — "Hyperphosphatemic Familial Tumoral Calcinosis"

Differential Diagnosis

Table 2. Genetic Disorders to Consider in the Differential Diagnosis of Hyperphosphatemic Familial Tumoral Calcinosis

Management Guidelines

Evaluations Following Initial Diagnosis

To establish the extent of disease and needs in an individual diagnosed with hyperphosphatemic familial tumoral calcinosis (HFTC), the following evaluations are recommended if not done at the time of diagnosis:

• Physical examination with particular attention to:

• Skin and joints to assess for tumoral calcinosis;

• Lower extremities to assess for edema, erythema, and pain related to hyperostosis;

• Peripheral pulses to assess for clinically significant vascular calcification.

Use ankle-brachial systolic pressure index to confirm clinical suspicion of lower-extremity arterial occlusive disease.

Source: GeneReviews — "Hyperphosphatemic Familial Tumoral Calcinosis"

Clinical Guidance

Because phosphorus-lowering medications are aimed at lowering the calcium X phosphate product, it is prudent to avoid the following:

• Use of calcium salts as phosphate binders

• Excessive dietary calcium intake

• Excessive vitamin D intake and/or supplements

• Foods high in phosphorus

Source: GeneReviews — "Hyperphosphatemic Familial Tumoral Calcinosis"

Therapies Under Investigation

Search ClinicalTrials.gov in the US and EU Clinical Trials Register in Europe for access to information on clinical studies for a wide range of diseases and conditions. Note: There may not be clinical trials for this disorder.

Source: GeneReviews — "Hyperphosphatemic Familial Tumoral Calcinosis"

Surveillance Guidelines

No specific guidelines address the issue of surveillance in HFTC. The frequency of monitoring depends on clinical findings and medical treatment, as there are no data to support an appropriate monitoring interval. Tumoral calcinosis. When initiating medical therapy the following should be monitored regularly:

• Blood phosphorus to help manage medication doses

• Blood calcium and intact parathyroid hormone because levels of 1,25D can be elevated

• Complete blood count, ESR, and CRP to assess for evidence of inflammation

• Renal function because hyperphosphatemia can contribute to development of kidney disease

Source: GeneReviews — "Hyperphosphatemic Familial Tumoral Calcinosis"