Diagnostic workup revealed artery dissection (n = 4), rare arterial diseases (n = 3), autoimmune vasculitis (n = 1), hypoperfusion with bilateral watershed infarcts (n = 1), decreased protein S levels (n = 1), and antiphospholipid syndrome with positive test of anticardiolipin antibodies (n = 1). The gene discussed is PROS1; the disease is autoimmune vasculitis.