Below is an instruction from Human. Write a response.
    ### Instruction:
    What causes Antiphospholipid Antibody Syndrome ?
    ### Response:
    Antiphospholipid antibody syndrome (APS) occurs if the body's immune system makes antibodies (proteins) that attack phospholipids.
                
Phospholipids are a type of fat found in all living cells and cell membranes, including blood cells and the lining of blood vessels.
    