Abstract Number: PB1293
Meeting: ISTH 2020 Congress
Background: Recent geno-phenotype analyses show a low risk for thromboembolic events (TEE) in patients with heterozygous AT deficiency type II, especially in carriers of variants affecting the Heparin binding site (HBS). Unusual presentations like abdominal thrombosis or arterial thromboembolic events in young children are rare.
Aims: To compare two new cases with unusal presentation with literature data.
Methods: Case report and literature review.
Results: The first patient is a 12 year old boy from Bosnia who presented with intestinal bleeding and a painful right leg. He had a history of short bowel syndrome due to several resections of the intestine performed of unclear reason in the neonatal period. Ultrasound revealed deep vein thrombosis (DVT) of both iliacal and the right femoral vein. An MRI angiography showed agenesis of the infrarenal cava vein with pelvic and lumbar collaterals. Because of persistent AT deficiency of 60% genetic testing was initiated and a heterozygous missense mutation in the SERPINC1 gene was found, which is causing AT type II HBS, known as AT-Rouen I.
The second child was admitted at the age of 4 years due to acute hemiparesis during an episode of acute respiratory infection. MRI and the clinical course of the disease were consistent with hemorrhagic encephalitis. Persistent decreased AT activity of 68% was observed. Genetic testing showed a heterozygous mutation in the SERPINC1 gene, known as AT type II HBS Basel.
Conclusions: We cannot prove that there is a causal relationship of AT deficiency and the unusual and early clinical presentation in our patients. We speculate that, in the first case, vena cava thrombosis in the perinatal period caused perfusion problems of the gut. Although the second case did not reveal typical radiological signs of arterial thromboembolic stroke we assume that AT deficiency together with hyperinflammation triggered thrombosis in small cerebral vessels.
To cite this abstract in AMA style:Beutel K, Liptay S, Makowski C, Eber S, Steinborn M-. Expanding the Spectrum of Heterozygous Antithrombin Deficiency Type II HBS? Unusual Presentation of Thromboembolic Events in Two Children [abstract]. Res Pract Thromb Haemost. 2020; 4 (Suppl 1). https://abstracts.isth.org/abstract/expanding-the-spectrum-of-heterozygous-antithrombin-deficiency-type-ii-hbs-unusual-presentation-of-thromboembolic-events-in-two-children/. Accessed January 26, 2022.
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