Thrombotic events in patients with congenital prekallikrein deficiency: a critical evaluation of all reported cases.

The occurrence of thrombotic events in patients with congenital bleeding conditions has received considerable attention in recent years. The same is true for asymptomatic defects of factors of the contact phase of blood coagulation, mainly FXII. Anecdotal reports on thrombosis in patients with prekallikrein deficiency have occasionally been reported. These involved both arterial and venous thrombosis. The purpose of the present article is to analyze the stories and the clinical pictures of all 75 cases of prekallikrein deficiency published so far. Among these patients were 9 with thrombosis, 6 arterial (myocardial infarction and ischemic stroke) and 3 venous (deep vein thrombosis with or without pulmonary embolism). In 6 cases acquired thrombosis risk factors were present; in 2 cases no associated risk factors were present and in 1 case no information was supplied in this regard. One patient who presented both a stroke and a pulmonary embolism had a fatal outcome. The article clearly indicates that prekallikrein deficiency does not protect from thrombosis in spite of the severe in vitro coagulation defect.

Sebastian syndrome: report of the first case in a South American family.

The Sebastian syndrome (SS) is a MYH9-related disorders, which are an extremely infrequent group of four autosomal dominant illnesses. SS consist of giant platelets, leukocyte inclusions and thrombocytopenia. To our knowledge, there are no case reports of this syndrome in South America. The propositus was a 35-year-old Argentine woman with a history of purpuric lesions in her lower limbs and thrombocytopenia. Idiopathic thrombocytopenia purpura (ITP) was previously diagnosed, but she did not respond to treatment with steroids. Family history failed to provide any evidence of hearing loss, easy bruising, nephritis, renal failure or cataracts. The patient and 11 members of her family were evaluated. The diagnosis of SS was established by demonstrating giant platelets, thrombocytopenia and leukocyte inclusions in peripheral smear in two relatives and by peripheral smear and electronic microscopy in the propositus. MYH9-related disorders should be suspected whenever a patient has a low platelet count or a bleeding diathesis of unknown origin. In these cases, the history, carefully peripheral smear exam, immunocytochemistry and electronic microscopy will be of great help. Differentiation ITP with SS is important to avoid unnecessary diagnostic studies and treatments.