Thrombotic thrombocytopenic purpura (TTP) is an ultra-rare, life-threatening disorder that is characterised by thrombocytopenia, haemolytic anaemia and organ ischaemia.1 The reported incidence in the UK is estimated to be at 6 per million and is more common in females than males.2,3
Acquired TTP (aTTP) is caused by autoantibody inhibition of the ADAMTS13 enzyme, also known as von Willebrand factor-cleaving protease, and it accounts for 95% of all TTP cases.2,4 The resulting decreased ADAMTS13 activity leads to the build up of the ultra-large von Willebrand factor multimers, which cause spontaneous and unrestrained platelet aggregation and subsequent microthrombi formation.4-6 aTTP episodes are associated with an acute mortality of up to 20%.7
1. Joly B, Coppo P, Veyradier A. Blood. 2017;129(21):2836-2846.
2. Orphanet. Thrombotic thrombocytopenic purpura. Accessed: July 2020.
3. Orphanet. Acquired thrombotic thrombocytopenic purpura. Accessed: July 2020.
4. Scully M, Hunt B, Benjamin S, et al. Br J Haematol. 2012;158:323–335.
5. Saad J and Schoenberger L. Physiology, Platelet Activation. [Updated 2018 Feb 20]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2018 Jan. Available from: . Accessed: July 2020
6. Sadler JE. Blood. 2008;112(1):11–18.
7. Benhamou Y, Boelle PY, Baudin B, et al. J Thromb Haemost. 2015;13(2):293–302.