An inquiry into the relationship between ABO blood group and thrombotic thrombocytopenic purpura

ABO blood group accounts for up to 40% of the variability in plasma von Willebrand factor (VWF) levels, which vary in the rank order AB > B > A > O > Bombay. This may be due in part to the influence of ABO-associated oligosaccharides on the proteolysis of VWF by the metalloprotease ADAMTS13, which is markedly deficient in thrombotic thrombocytopenic purpura (TTP). Using ABO blood group as a surrogate for baseline VWF levels as well as susceptibility to proteolysis by ADAMST13, we set out to determine whether ABO blood group influences the clinical course of TTP. We conducted a retrospective analysis of the clinical course of 76 patients with primary, sporadic TTP treated at two institutions over the past 10 years. We found no significant differences between group O and non-O patients with respect to presenting platelet count and lactate dehydrogenase concentration, maximum serum creatinine concentration, and total number of therapeutic plasma exchanges per episode. Substrate-related contributors to the highly variable phenotype and clinical course of TTP warrant further investigation.