PB0637 - A first care report of congenital thrombotic thrombocytopenic purpura (cTTP) in ADAMTS13 gene in Thailand

Background: cTTP, a life-threatening disease with an incidence of 2:1,000,000 per year, is a rare autosomal recessive inheritance disease caused by severe depletion of the von Willebrand cleaving protease, a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13 (ADAMTS13) from ADAMTS13 gene mutation. Clinical presentations are variable from neonate, childhood to adult.

Aims: A first case report with cTTP has identified a genetic mutation of ADAMTS13.

Methods: a case report

Results: A 13-year-old boy presented with acute chest pain at 5 years of age. He has a history of neonatal jaundice and required a phototherapy. He was diagnosed with immune thrombocytopenia (ITP) at 1 year of age with regular red cell and platelet transfusion. ITP was not responding to prednisolone. He also has a history of alteration of consciousness and seizure 2 months before this episode with no evidence of intracerebral hemorrhage. His physical examination demonstrated generalized ecchymosis in both legs. Investigation findings reveal as follows; Hb 4.8 g/dL, MCV 100.2fL, platelet count 21,000/cumm, Reticulocyte 33.5%, NRC 813/100RBC, normal PT and aPTT. A blood smear demonstrates microangiopathic hemolytic anemia. Other investigation shows BUN 53, Creatinine 0.7 mg/dl, LDH 7499, AST 151, ALT 40 U/L. ADAMTS13 levels of the patient, his mother, and his father are less than 3, 34, and 45% (Normal range 58-170%) respectively. Fresh frozen plasma has commenced weekly with platelet count rising at week 2 and hemoglobin at week 3. FFP is given every 2 weeks with no other transfusion requirement. He developed multiple gallstones from abdominal ultrasound surveillance. The ADAMTS 13 gene mutation analysis demonstrates compound heterozygous c.768_774dup, (p.Gly259ProfsTer133 (pathogenic)) and c.304C>T, p.Arg102Cys (pathogenic).

Conclusion(s): The mutation of ADAMTS13 might determine the severity and clinical onset. In case of ITP presenting in a younger age along with hemolytic anemia, ADAMTS 13 should be performed to exclude cTTP.