Apart from conventional biological markers (LA, aCL and aβ2GP1), numerous other markers of APS have been studied such as antibodies against phosphatidyl-ethanolamine (16), phosphatidylserine-prothrombin (17), that could be helpful in the diagnosis of so-called seronegative APS (SNAPS) (18, 19), which defines a group of patients with clinical manifestations of APS but with persistently negative aCL, aβ2GP1 antibodies and LA. This evidence concerns the gene F2 and autoimmune polyendocrinopathy.