This is a gold-standard, highly specific test for diagnosing Antiphospholipid Syndrome (APS). It detects the "memory" (IgG) antibodies that directly attack Beta-2-Glycoprotein 1, a key protein in your blood. The presence of these long-term antibodies is one of the strongest and most reliable markers for this autoimmune condition, which is a major cause of recurrent blood clots and miscarriages. This simple blood test provides the definitive, specific evidence your doctor needs to confirm your diagnosis and build your long-term care plan.