Ankylosing spondylitis can run in families, and the HLA-B27 gene can be inherited from another family member.
If you have Ankylosing spondylitis and tests show you carry the HLA-B27 gene then there is a 1 in 2 chance that you could pass on the gene to any children you have. It is estimated that between 5 to 20% of children with this gene will then go on to develop Ankylosing spondylitis.
Ankylosing spondylitis is not purely a genetic disease, although it can occur in more than one person in a family. Since the risk of developing the disorder is likely influenced by multiple genetic and environmental factors, if someone inherits a genetic variation linked to ankylosing spondylitis, this does not mean they will develop it. This is true even when more than one family member has the disorder.
The risk of a child developing ankylosing spondylitis is less than 20 percent if their parents carry the HLA-B27 gene. This means that about 80 percent of children who inherit HLA-B27 from a parent with ankylosing spondylitis do not develop the disorder. A person is three times more likely to develop the disease if they have a close relative with the condition.