Genetics of Ankylosing Spondylitis. What’s the risk for your child?

Ankylosing spondylitis (AS) is a type of arthritis that affects the spine and pelvis. Changes in genes contribute to the risk of people developing ankylosing spondylitis.

One gene makes a strong contribution to the risk of arthritis, it’s called HLA-B27. Around 70-80% of people with ankylosing spondylitis have the HLA-B27 gene.

What does that mean for the children of people with ankylosing spondylitis?

Well luckily the risk is pretty low and there are some pretty good treatments for ankylosing spondylitis, so I don’t think that people should be making decisions to have children or not have children based on the fact they have ankylosing spondylitis.

These are the reasons why:

• The HLA-B27 gene is common in the European descendent community, around 7-9% of people carry this gene. 

• Importantly only 1-5% of people who inherit the gene develop AS. So almost everyone with the gene actually doesn’t have AS.

• There are a number of other genes that contribute to your risk of AS, but the effect they have is so tiny as to make it not relevant for people when assessing risk to their family.

• So scientific research has shown that even if you have AS and you have children, the risk of them having AS is only around 8%. If one child has AS the risk that their brother or sister will develop it is also 8%.

It is important to remember that there are a number of good treatments for ankylosing spondylitis, including anti-TNF agents, anti-IL12/23 agents, anti-IL17 agents, non-steroidal anti-inflammatories, and not to forget good old physiotherapy, which has been shown to reduce pain and stiffness and increase function.

People with ankylosing spondylitis usually lead normal lives and have families and do all the things that other people do.

If you would like to read more about the genetics of ankylosing spondylitis, you can read these medical journal articles about it here or here.

About the author: Philip Robinson is a rheumatologist in Brisbane who has a PhD in the genetics of ankylosing spondylitis. He has a blog at arthritiskare.com and is on twitter @philipcrobinson. His practice website is brisbanerheumatology.com.au