Thrombotic thrombocytopenic purpura (abbreviated TTP) is a rare disease that is caused by the occurrence of blood clots (so-called blood platelet thrombi) in small and the smallest blood vessels. Blockage of vessels leads to lesions in the affected organs as a result of which stroke, kidney dysfunction, etc. can arise. If left untreated, the disease leads to death in 90% of cases.
For the most part we now distinguish between two forms, acquired TTP and congenital (= hereditary or familial) TTP. The congenital form is also called Upshaw-Schulman Syndrome, having been named after those who first described it. Upshaw-Schulman Syndrome is caused by genetic defects (mutations) in the ADAMTS13 (= Von Willebrand factor-cleaving protease) gene. This results in functional ADAMTS13 no longer being able to be formed. Hence, ADAMTS13 activity that can be measured in plasma of Upshaw-Schulman Syndrome patients amounts to less than 5% of normal levels.
Various case reports about individual patients have been published since the Von Willebrand factor-cleaving protease (ADAMTS13) and the connection between a serious ADAMTS13 deficiency and TTP have been discovered. Based on this, we estimate that there are currently approximately 150 families with known Upshaw-Schulman in the world. Unfortunately, since too little is known about Upshaw-Schulman Syndrome at this time, the disease is often diagnosed too late or not at all and many patients or their siblings have either died or suffered extremely serious, permanent organ damage from it. This is all the more unfortunate since acute TTP episodes in Upshaw-Schulman Syndrome patients can be successfully treated with simple plasma infusions. Today, there are numerous patients receiving plasma infusions every 2-3 weeks to prevent recurring episodes and living normal lives. These days the question remains open as to whether all patients should receive this type of preventative treatment, or perhaps certain specific situations warrant the use of some other therapy that may not be as effective in reducing the risk of an episode’s occurring. (And what would these specific situations be?)