Genetic predispositions for TPP previously documented in the literature include mutations in the SCN4A (sodium voltage-gated channel alpha unit 4) gene (70% TTP cases) and in the CACNA1s (calcium voltage-gated channel alpha subunit 4 S) gene (10% TPP cases) [12]. The gene discussed is CACNA1S; the disease is thrombotic thrombocytopenic purpura.