Does RA Run in Families?
Last updated: August 2022
Editor's note: An earlier version of this article incorrectly stated that vitamin D supplementation increases a person's risk of developing rheumatoid arthritis (RA). Research shows that vitamin D has many potential benefits in people with RA.
While up to 18 million people in the world live with rheumatoid arthritis (RA), many are unsure about what causes a person to develop RA.1
It’s definitely a disease shrouded in mystery. Is RA something you are born with and runs in families? Or is it caused by independent environmental factors throughout your lifetime? In reality, the answer is not as simple as the question.
As researchers have further studied RA, they have started to better understand the causes of the condition. In fact, research shows RA occurs as a result of the relationship between both genetics and environmental factors.2
What causes RA?
The causes of RA can be separated into 2 categories: genetics and environmental factors.2
RA is not directly passed on from 1 generation to the next like with some other genetic disorders. Many people may have a relative with RA but never develop it, while some people diagnosed with RA have no family history of the condition.2
Through the use of twin studies, experts estimate that genetics are a factor in more than 50 percent of people with RA.2
Experts have also studied environmental factors and their link to the development of RA, including:2-4
Smoking – Smoking increases the risk of having RA. In fact, the risk of RA increases with the duration and number of cigarettes smoked. For someone who smokes a pack a day for 40 years, the risk is twofold in comparison to those who never smoked.
Infectious disease – The role of infectious diseases in the development of RA has long been studied. Experts think that some infections may initiate the onset of RA when they trigger the immune system. Some infections that have been linked to RA include Epstein-Barr virus (EBV), Mycobacterium tuberculosis, Escherichia coli (E. coli), Proteus mirabilis, and parvovirus B19.
What’s the risk of developing RA if a family member has it?
While RA is not passed from one generation to another, you have an increased risk of developing the condition if you have a family member with RA. In one Swedish study, people with a first-degree relative (parent, sibling, or child) with RA were roughly 3 times more likely to develop RA compared to first-degree relatives of people in the general population.2
While the estimates vary from one study to another, research shows there seems to be a family link to RA.
What is the role of genetics in rheumatoid arthritis?
You may be wondering why genetics are important if RA does not run in families in a direct line of inheritance like some genetic disorders. While this is true, the study of genetics in RA could lead to advancements in the diagnosis and treatment of RA such as:2
- Predicting a person's response to different treatments
- Predicting who will develop RA
- Predicting how severe someone’s RA will be
- Developing different types of treatments for RA
Does RA run in your families at all? Share your experience between RA and genetics with us below.
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