Tumoral calcinosis is an inherited disorder that is characterized by the presence of lumps of calcium at inappropriate sites in the body, such as around the hip, elbow, shoulder, and knee joints.
Previously, mutations in two genes (FGF23 and GALNT3) had been shown to cause this disease. Now, researchers from Indiana University School of Medicine have identified in a third gene a mutation that causes tumoral calcinosis.
In the study, which appears online on August 16 in advance of publication in the September print issue of the Journal of Clinical Investigation, Michael Econs and colleagues show that a 13 year old girl with tumoral calcinosis has a mutation in both copies of her KL gene.
In vitro analysis revealed that the KL protein resulting from this mutation was expressed and secreted at lower levels than normal KL and that it was unable to help FGF23 mediate its functions.
This study provides insight into why mutations in the KL gene cause tumoral calcinosis and gives clinicians a new candidate gene to consider when attempting to determine the etiology of tumoral calcinosis.
Article: A homozygous missense mutation in human KLOTHO causes severe tumoral calcinosis
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