The latter is more common than hereditary forms and can result from various conditions, including vitamin K deficiency, liver disease, DIC, nephrotic syndrome due to protein S loss, pregnancy, oral contraceptives, hormone replacement therapy, autoimmune disorders such as APS and systemic lupus erythematosus (SLE), because autoantibodies can bind to protein S, reducing its function. This evidence concerns the gene PROS1 and autoimmune polyendocrinopathy.