Maleet al

Maleet al. were assigned to group I, while the other 11 (25%) formed group II. Major associated diseases in group I were urticarial vasculitis (21%), acute infections (18%) and thalassaemia (12%). Five subjects (15%) were asymptomatic. Four out of the 11 subjects (36%) in group II had thrombotic events; they were all persistently aPL-positive and two of them had concomitant systemic lupus erythematosus. The rate of detection of LA-positivity was not significantly different between the two groups (76% vs 91%, p>0.05), whereas the percentage of patients positive for overall aCL was higher in group II than in group I (54% vs 42%, respectively; p<0.05). Specifically, aCL IgG and anti-2GPI IgM subtypes were significantly more represented in group II than in group I (100% vs 62% and 75% vs 33%, respectively; p<0.05). == Discussion. == Our study shows that aPL-positive children have different features that should be BMS-582949 taken into account in the classification of criteria for paediatric APS. Keywords:activated partial thromboplastin time, antiphospholipid antibodies, children, thrombosis == Introduction == Antiphospholipid antibodies (aPL) are a heterogeneous class of auto-antibodies directed against BMS-582949 plasma proteins with affinity for anionic phospholipids1. Among the clinically relevant aPL, the most frequently encountered are lupus anticoagulant (LA), anticardiolipin (aCL) and anti-2-glycoprotein I (anti-2GPI) antibodies1. The association of thrombotic events or recurrent miscarriages with the presence of circulating aPL on two individual occasions, at 12 weeks apart, defines the antiphosholipid syndrome (APS)2. APS may be secondary to other underlying conditions, notably systemic lupus erythematosus (SLE), or may occur as an isolated clinical entity, in which BMS-582949 case it is known as primary APS1,2. Not all patients with aPL antibodies develop APS, as such antibodies have been found in about 5% of the healthy populace3,4. There is a high incidence of transient aPL antibodies in children after viral and bacterial infections; these antibodies are thought to be clinically irrelevant58. Although aPL have been mainly associated with thrombotic features, especially recurrent venous thrombosis, some additional clinical manifestations, including bleeding abnormalities, have been described1,9,10. Pathways potentially leading to thrombosis include the direct activation of coagulation, inhibition of anticoagulation and interference with endothelial cells, immunocompetent cells and platelets11,14. Because many individuals with high aPL titres remain asymptomatic, a two-hit hypothesis has been proposed to BMS-582949 explain the mechanisms by which they might cause diseases. According to this hypothesis, the presence of aPL antibodies induces endothelial dysfunction (first hit) and another condition, such as pregnancy, infection, smoking, hypertension, atherosclerosis, obesity or vascular injury (second hit) triggers thrombosis15,16. There are no systematic studies on APS in childhood because of the relatively low prevalence and heterogeneity of this syndrome in paediatric patients, although the Ped-APS Register, a collaborative project of the European Forum on Antiphospholipid Antibodies and the Lupus Working Group of the Paediatric Rheumatology European Society currently contains standardised data from 133 children in 14 countries with aPL-related thrombosis17,18. One of the aims of this project is usually to define the prevalence and prognosis of unusual, different foms of APS. The purpose of this study was to assess Rabbit polyclonal to KATNA1 clinical and laboratory characteristics of a cohort of aPL-positive children to contribute to the understanding of the heterogeneous aPL-related features in childhood. == Materials and methods BMS-582949 == == Study populace == Between January 2000 and December 2010 we enrolled in a prospective study all examined patients aged 6 months to 18 years with prolonged activated partial thromboplastin time (aPTT), not corrected by the addition of normal plasma, whose parents/guardians gave consent to the childrens participation in the study. These subjects were referred to us for pre-operative coagulation counselling or because of abnormal clotting assessments, thrombosis or bleeding. Patients with LA and/or aCL and/or anti-2GPI antibodies positive on only one occasion were assigned to group I (transiently positive), while patients with elevated plasma levels of aPL on two or more occasions, at least 12 weeks apart, were assigned to group II (persistently positive). The clinical and.