Although his ADAMTS13 level was not suggestive of TTP, at 54.4% (normal low ADAMTS13: >66.8% activity; severe ADAMTS13 deficiency: <i>≤</i>10% activity), he improved only after plasmapheresis was initiated, supporting a diagnosis of a TTP-like syndrome likely due to his streptococcal meningitis. This evidence concerns the gene ADAMTS13 and thrombotic thrombocytopenic purpura.