Explore Disease States. TTP Thrombotic Thrombocytopenic Purpura. Thrombotic Thrombocytopenic Purpura (TTP) is a rare, life-threatening disorder of the blood-coagulation system which causes microscopic clots to form in small blood vessels throughout the body. Although it’s rare, TTP affects about 4 to 6 people per million per year, most often women and African-Americans.