Once both IE and BCNE have been excluded, supplementary laboratory investigations are needed to search for NBTE-predisposing conditions like autoimmune disorders (particularly LES and APLs), cancer, and hypercoagulability, through immunological assays (i.e., antinuclear antibody, extractable nuclear antigens, anti-double stranded DNA, rheumatoid factor, anticardiolipin, and anti-β2-glycoprotein 1 antibodies), tumor markers, coagulation profile (prothrombin time, partial thromboplastin time, fibrinogen, D-dimers, and cross-linked fibrin degradation products) [3,5,8,25]. This evidence concerns the gene F2 and autoimmune disease.