ADAMTS13 and congenital thrombotic thrombocytopenic purpura: TTP is suspected when ADAMTS-13 activity is ≤ 10% and is typically acquired due to auto-antibodies against ADAMTS-13 (approximately 95% of cases) but can also be congenital (Upshaw-Schulman syndrome) due to mutations on the corresponding gene affecting ADAMTS-13 function [5, 6].