Calcification of joints and arteries (CALJA) is a rare autosomal recessive disorder caused by a mutation of the NT5E gene. It is characterized by extensive calcifications in the limb arteries and in the joints of the hands and feet.
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Epidemiology
CALJA is a very rare disorder; up to now, less than 20 patients have been reported 1. Patients may become symptomatic from the second decade of life.
Clinical presentation
The symptoms are associated with the location of the calcifications. Arterial calcifications cause narrowing of the vessels and ischemic symptoms, ranging from paresthesias, pain, and intermittent claudication to occlusion (usually with extensive collateral circulation). The ankle-brachial index is decreased in these patients.
Calcifications of the joints may cause pain, swelling, and stiffness.
Pathology
The disorder is caused by a mutation of the NT5E gene, which encodes enzyme CD73, responsible for converting AMP to adenosine and helping to inhibit the formation of tissue calcifications.
Radiographic features
Plain radiograph
X-rays show extensive calcifications of the limb arteries, with areas of aneurysmatic dilatation. Aorta, carotid, and coronary arteries are spared.
Juxta- and periarticular calcifications are present, most often in the joints of the hands and feet.
CT/CT angiography
CT confirms the presence of calcifications. CTA is used to calculate the degree of arterial narrowing.
Treatment and prognosis
Progressive vessel calcification may lead to limb ischemia and amputation. Vessel occlusion may require arterial bypass surgery.
Differential diagnosis
The appearance of the joints may resemble other entities associated with periarticular soft-tissue calcifications. The key to the diagnosis is the characteristic appearance of arteries, which should prompt genetic testing.
History
The combination of arterial and periarticular calcifications was first described by Magnus-Levy in 1914. The supposition of the hereditary nature of the condition was made by Sharp in 1954 3. In 2011, the mutation causing CALJA have been identified by St. Hilaire et al. 2.