Ankylosing spondylitis (AS) is a chronic inflammatory disease that affects the joints between the vertebrae of the spine and the joints between the spine and the pelvis. The purpose of this study is to collect information and blood samples from patients with AS and their relatives for use in genetic studies.

AS is a chronic inflammatory disease that eventually causes the affected vertebrae to fuse or grow together. The cause of AS is unknown, but genetic factors seem to play a role. Risk factors include a family history of ankylosing spondylitis and male gender.

This study will collect patient information and blood samples from affected patients (and when available, both parents of the affected patients) of 400 families with children fulfillling the modified New York criteria for AS. Diagnosis of AS will be verified by patient questionnaire, medical record review, and pelvic radiographs. Information from these patients will be used to search the human genome for disease-associated loci and/or genes. This study will also utilize contributions of investigators who have conducted recent clinical or genetic research in AS at 10 academic medical centers throughout North America (the North American Spondylitis Consortium, or NASC).

Inclusion Criteria:

• Meet modified New York criteria for ankylosing spondylitis (AS)
• AS as confirmed by X-rays of sacroiliac joints (between the pelvis and spine)
• At least two siblings in family with AS
• Parents of the participants with AS have the option of also being enrolled