Our 22-year old son was just diagnosed with ankylosing spondylitis. We've been told this runs in families. Should everyone else be tested? What's the next step?
Talk with the physician who made the diagnosis. There is a familial risk for ankylosing spondylitis meaning it does have a hereditary component and seems to occur within families. Studies show there are both genetic and environmental factors. About 65 per cent of the cases have a genetic basis. The physician can assess the risk of AS and related diseases in the family and make recommendations. Sometimes this involves testing family members for the presence of the HLA-B27 gene. This test is helpful but not conclusive. Some people who have AS don't have this gene. But, in general, people who have the HLA-B27 gene have a higher risk of developing AS than those who don't have this gene. New research also shows there may be other genes involved (e.g., interleukin 23 receptor gene, ARTS1 gene). The presence of back pain in someone with the gene is a yellow (warning) flag. Family members will be questioned closely about their history of signs and symptoms suggestive of AS. An MRI scan of the sacroiliac joints and spine may be needed. The MRI can show early changes that don't appear on X-rays. Men are 10 times more likely to be affected compared to women. When AS affects women (mother, sisters, children) of the patient with AS, they are more likely to have changes in the thoracic spine and costovertebral joints (where the ribs attach to the vertebrae).