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. The gene discussed is PROS1; the disease is systemic lupus erythematosus.