APS is an autoimmune disorder that causes an increased risk for developing a venous or arterial thromboembolism, as well as recurrent miscarriages. APS frequently occurs in people with lupus, and is referred to as secondary APS in this case. Many people who have APS, however, do not have another autoimmune disorder, and their disease is referred to as primary APS. APS may be a genetic disorder, and identifying the gene(s) that predisposes an individual to develop it could lead to a better understanding of the disease, as well as improved therapies. This study will use a genetic strategy to identify potential risk factors for the development of APS by recruiting people with APS who have family members who are either affected by the syndrome or who have another autoimmune disorder. The results of the genetic testing will be compared among the following two groups of families: people with APS who also have one or more of their family members affected specifically... (for more see dbGaP study page.)