ADAMTS13 and thrombotic thrombocytopenic purpura: To determine if a similar association is present in ADAMTS13-deficient TTP patients without any known overlapping rheumatic diseases, the patient serum samples were tested for autoantibodies to the Ro, La, Sm and nRNP RNA-binding proteins using antigen-specific ELISAs and the data compared with presence of the type 1 IFN gene signature.