Pediatric antiphospholipid syndrome.

Antiphospholipid syndrome is a multisystem autoimmune disease , characterized by arterial and venous thrombosis, recurrent fetal loss, and persistent circulating antiphospholipid antibodies [1]. This syndrome with protean clinical manifestations can be either primary or secondary to other autoimmune disease, mainly systemic lupus erythematosus. Whereas APS in adults has been well characterized, only a few studies of children with APS have been reported, most of them case reports [2-5]. The first pediatric series, published in 1996, included nine patients [6]. In a review of 50 case reports of children with APS, Ravelli and Martini [7] concluded that pediatric APS is similar to adult APS. Later it was shown that patients with childhood-onset APS presented with significantly more episodes of chorea and jugular vein thrombosis than did adults [8]. Pediatric primary APS is very rare, and disease onset before age 15 occurred in only 2.8% of patients from a large APS cohort [8]. The prevalence of secondary APS in children with SLE is 9–14% [9,10]. The recently revised criteria for the diagnosis of APS in adults are currently used for pediatric patients, but there is no validation of these criteria for children [5]. Laboratory tests The aPL antibodies, directed against phospholipids and phospho-lipid-binding proteins, are tested by coagulation or immunologic assays. The aPL antibodies have both pro-and anti-coagulant properties; they alter coagulation tests, causing inhibition that is not corrected by addition of normal plasma. Several tests for aPL are available. The prolonged activated partial thromboplastin time test has a low sensitivity; kaolin clotting time is too complicated to assay. dRVVT (Russell viper venom time) is very sensitive to phospholipid interference and is currently the preferred test for lupus anticoagulant detection. Other tests for measuring aPL antibody are immunological, namely, the enzyme-linked immuno-sorbent assay, which detects different isotypes of anticardiolipins and antibodies to many other phospholipids (phosphatidylserine, phosphatidylinositol, phosphatidylcholine) [11]. Their specificity increases with the titer, and immunoglobulin G anticardiolipin is more specific than immunoglobulin M. Another group of antibod-APS = antiphospholipid syndrome aPL = antiphospholipid ies is directed against protein co-factors that bind the phospho-lipids, such as beta-2 glycoprotein-1 and annexin. Although there is some overlap between all these antibodies, it is important to use more than one test to detect them. The revised criteria for the definition of APS include a combination of one of two clinical (thrombosis/recurrent abortions) and one of three laboratory features. The laboratory criteria are positive lupus …