Clinical and laboratory characteristics of children positive for antiphospholipid antibodies

in childhood. Materials and methods. Forty-four patients with prolonged activated partial thromboplastin time were enrolled and assigned to group I ("transiently positive") or group II ("persistently positive"), based on the detection of elevated aPL plasma levels [lupus anticoagulant (LA), anticardiolipin (aCL), and anti-β2-glycoprotein I (anti-β2GPI) antibodies] on, respectively, one or more occasions, at least 12 weeks apart, by standard procedures. The clinical history and symptoms of all patients were recorded. Results. Thirty-three (75%) patients 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 aPLpositive and two of them had concomitant systemic lupus erythematosus. The rate of detection of LA-positivity was not signifi cantly 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). Specifi cally, aCL IgG and anti-β2GPI IgM subtypes were signifi cantly 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 taken into account in the classifi cation of criteria for paediatric APS.