Antiphospholipid antibodies and stroke in Down syndrome.

Two patients with Down syndrome and the primary antiphospholipid antibody are described. One patient had a vasculopathy similar to that previously described as Moyamoya. Down syndrome is characterized by immune defects including a tendency to autoimmune phenomena. This report extends the scope of these observations and particularly draws out the potential role of antiphospholipid antibodies. Indeed antiphospholipid antibodies may well explain the well-known association of Down syndrome and stroke.