INF2 and thrombotic thrombocytopenic purpura: Primary genetic causes encompass: deficiency of ADAMTS13 (known as thrombotic thrombocytopenic purpura (TTP)); complement-mediated hemolytic uremic syndrome (HUS), also known as atypical hemolytic uremic syndrome (aHUS) [1, 2, 5]; cobalamin C hemolytic uremic syndrome, due to a rare autosomal recessive disorder of cobalamin metabolism [2, 5]; and mutations in DGKE (diacylglycerol epsilon), and in the INF2 (inverted formin 2) gene [2].