Is RA Hereditary?
Editor's note: This article was first published in May 2015. Since then, more research has been conducted to understand the role of genetics in rheumatoid arthritis. Read this recent study on genetic susceptibility and RA: Genetics of rheumatoid arthritis: 2018 status that was published in Annals of the Rheumatic Diseases in 2019.
When I made the decision to become a mom after my diagnosis of rheumatoid arthritis, one of the first questions on my mind was this: is RA hereditary? Will I pass RA on to my children? Having suffered for years with RA, the very last thing in the world I would ever want would be to watch my children suffer as I have.
Luckily, the short answer to this question is this: No. You can’t pass RA directly to your children.
Hereditary versus genetic: What's the difference?
There is often a lot of confusion surrounding this issue. Part of the problem is that scientists still aren’t exactly sure what causes RA. However, like most human diseases, scientists do think that there is a genetic component to the disease. But a genetic component that influences susceptibility is not the same as a disease being hereditary.
I am not a scientist – I’m just a concerned mother living with RA! But I am going to try to do my best to explain this issue in order to help other moms (and moms-to-be) who share this concern.
Genetic susceptibility to RA
For starters, it helps to understand a little bit about the disease we are dealing with. RA is an autoimmune disease – meaning the body’s immune system mistakenly attacks the membranes that line healthy joints. The result is inflammation and pain in the joints, which can sometimes affect other bodily systems.
The exact cause of this mistaken attack by the immune system is still not clear but, as with other autoimmune diseases, researchers do think that some people may be genetically more susceptible. This means that it is theoretically possible to pass genes to your children that could make them potentially more susceptible. But it is important to remember that it does not mean they will necessarily develop RA.
The role of genetics in disease
There are approximately 25,000 genes that influence human traits like appearance, personality, and susceptibility to different diseases. These genes vary from person to person, and when these genes are mutated, they can cause disease. In some cases, passing a single mutated gene to your child will be enough for them to develop a disease. These diseases are called unifactorial.
Examples of unifactorial diseases
Sickle cell anemia is an example of a unifactorial disease where, if both parents pass a mutated gene to their child, the child will inherit the disease. Another example is Marfan syndrome, which requires a mutated gene from only one parent for the child to inherit the disease.
Rheumatoid arthritis is a multifactorial disease
But RA is not a unifactorial disease. Instead it is multifactorial, which means that it is caused by a complicated interaction of multiple genes and environmental factors. This means that for a person to be genetically susceptible to developing RA, they need to inherit not just one specific gene from their parents, but several different genes. And having these genes will not necessarily lead to the disease.
For example, of the various genes that affect RA susceptibility, scientists have been able to identify one gene that is linked specifically to RA, named HLA-DR4. This gene is found in about 30% of the general population, and in RA patients of European ancestry, as many as 60 to 70% carry this specific gene. But, importantly, not everyone with this gene will necessarily develop RA. And my understanding is that not everyone who has RA has this gene.
Environmental factors could play a role
That’s because scientists have not been able to identify a single cause for RA. Instead, in addition to genetic susceptibility, scientists think various environmental factors also play a role. This includes theories such as viruses or bacteria that trigger the faulty immune response. Gender, age, ethnicity, and nutrition are also thought to play a role.
Additionally, researchers are studying the effects of physical trauma, emotional stress, and female hormones. And, according to the U.S. Centers for Disease Control and Prevention, smoking can increase your risk for developing RA as compared to nonsmokers. So, even if your child does turn out to be genetically susceptible to developing RA, there are many other factors at play that help determine whether they will actually develop it.
Are my children genetically susceptible to RA?
Unfortunately, it’s not impossible. There are always risks when it comes to having children, and there is a slightly increased risk that my children could be genetically susceptible to eventually developing RA or another autoimmune disease. But this risk is small.
According to a study done by Harvard Medical School, one out of 100 people in the general population will develop RA. But out of 100 people with a first-degree relative (meaning mother, father, sister, or brother) with RA, only four will be likely to develop RA. This means that first-degree relatives have only a slightly increased risk of developing RA than the general population.
Also, given their family history and my own experiences, if my children did develop symptoms someday they would be diagnosed and treated quickly. And they would certainly have an understanding and supportive family to help them through it all.
(Would you like to learn more? Much of this information was taken from the American College of Rheumatology's Heredity and Arthritis).
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