Effect of blood groups on acquired and congenital thrombotic thrombocytopenic purpura and clinical correlation: Multi-center Turkish cohort study Cevat ¿lteri¿ K¿k¿l¿; Damla Ortaboz; Melek Yana¿¿k; Muhlis Cem Ar; Sevgi Kalayo¿lu Be¿¿¿¿k;