Background: Congenital deficiency of ADAMTS13 is characterized by systemic platelet clumping, hemolytic anemia and multiorgan failure. Although, more than 100 mutations have been reported, atypical clinical presentation may be involved in diagnostic difficulties.
Case report: A 2 year old Tunisian child presented with chronic thrombopenic purpura which failed to respond to corticosteroids. Hemolytic anemia with schizocytes, occurred ten months later, with no previous history of diarrhea or any neurological abnormality. Renal function, coagulation screening tests and complement assay were normal. The count of platelet improved after fresh frozen infusion (FFP). Extensive investigations revealed a severe deficiency of ADAMTS 13 activity (level< 5%). Gene sequencing identified mutation in exon 18 of ADAMTS 13 gene. Prophylactic regimen with regular infusions of FFP was associated to favorable outcome. Conclusion: Early ADAMTS 13 activity testing and gene sequencing associated to precocious plasmatherapy are crucial to reduce morbidity and mortality of congenital TTP.