Does RA Run in Families?
Although rheumatoid arthritis (RA) is the most common autoimmune inflammatory joint disease in the world, many people are unsure about what causes an individual to have RA.2
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 studied RA further, they have begun to understand the causes of RA more and more. In fact, research shows RA occurs as a result of the relationship between both genetics and environmental factors. Simply, RA occurs when a predisposition of RA in your genetics is then turned on by something in our environment.1
What causes RA?
The causes of RA can be separated into 2 categories: genetics and environmental factors.
RA is not directly passed on from 1 generation to the next such as some other genetic disorders. Many patients may have a relative with RA but never get it, or vice versa, as a patient diagnosed with RA may have no family history.2
Through the use of twin studies, it’s estimated that genetic factors account for more than half the disease susceptibility, between 53 and 68 percent in an individual.2
There are numerous environmental factors that have been studied and are thought to be connected to the development of RA.
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.2
Vitamin D - In many disorders, vitamin D supplementation is thought to be protective. However, in the case of RA, the opposite is true. There’s an inverse association between Vitamin D supplementation and RA, meaning study participants who received supplementation had an increased risk of developing RA.2
Infectious disease - The presence of infection has been thought to initiate the onset of RA due to its activation of the immune system as a whole. Some of the different infections that have been connected to RA include Epstein-Barr virus (EBV), Mycobacterium tuberculosis, Escherichia coli, Proteus mirabilis, retroviruses, and parvovirus B19.3,4 This section of the field of study into the causes of RA is increasingly growing.
What’s the risk of developing RA if a family member has it?
Although RA isn’t passed from one generation to another, there is an increased risk of developing RA if you have a family member with RA. In one Swedish study, there was 3x greater risk of developing RA with a first-degree relative (parent, sibling, or child) with the condition, in comparison to the general population.2 Although the estimates vary from one study to another there seems to be a familial connection to RA.
What is the role of genetics in rheumatoid arthritis?
You may be wondering why genetics are important if RA doesn’t run in families in a direct line of inheritance like some genetic disorders. Although this is true, the study of genetics in RA could lead to advancements in treatment and detection of RA such as:1
- Predicting an individual’s response to different treatments
- Predicting who will develop RA
- Predicting how severe someone’s RA will be
- Developing different type of treatments and medications
Does RA run in your families at all? Share your experience between RA and genetics with us below.
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