Rheumatoid Arthritis Risk Factors: Is It Hereditary?
About Rheumatoid Arthritis
Rheumatoid arthritis (RA) is an autoimmune disease in which the body’s immune system mistakenly attacks the membranes that line the body’s joints. The result is inflammation and pain in the joints. RA is a chronic disease that can cause periods of intense activity called flare-ups. Some people experience periods of remission in which symptoms go away. The Arthritis Foundation estimates that 1.3 million people in the U.S. have RA.
What Causes the Faulty Immune System Response?
The exact cause of the immune system’s faulty response is unclear. As with other autoimmune diseases, researchers think some people may be genetically more likely to develop RA. They also theorize that there are environmental factors, such as viruses or bacteria that trigger this faulty autoimmune response. Researchers are also studying the role of emotional stress, physical trauma, and female hormones in RA. Smoking may make people more likely to develop RA, depending on their genetics.
Gender, Age, and Ethnicity
Almost three times as many women have RA than men, according to the Arthritis Foundation. Although adolescents and young adults in their 20s can have RA, overall risk increases as you age. Women tend to be diagnosed between the ages of 30 and 60. Men are usually older than that when they are diagnosed. RA can be found all around the world and in every ethnic group.
Environmental and Behavioral Risk Factors
The U.S. Centers for Disease Control and Prevention say that if you have a history of smoking, your risk for developing RA is increased by 1.3 to 2.4 times compared to nonsmokers. Other potential risk factors include the use of oral contraceptives or hormone replacement therapy. There may be a link between an irregular menstrual history and RA. Women who have given birth or breastfed may have a slightly decreased risk of developing RA.
According to Harvard Medical School, out of 100 people with a first-degree relative (mother, father, sister, or brother) with RA, only four will go on to develop RA. Compare that with the general population, where one out of 100 will develop RA. This means first-degree relatives are only at a slightly increased risk of developing RA. (Note: this does not take various environmental factors into account.)
Scientists have gained a lot of insight into the connection between genetics and disease by studying twins. The genetics of non-identical twins are as similar as any pair of non-twin siblings. Identical twins, however, have exactly the same genes. According to the American College of Rheumatology, four percent of non-identical twins will eventually develop RA. When it comes to identical twins, that figure is more like 12 to 15 percent.
The immune system protects us by attacking foreign substances that invade the body. Sometimes the immune system is fooled into attacking healthy parts of our bodies. Some of the genes thought to be responsible for RA are also involved in other autoimmune diseases, such as type 1 diabetes and multiple sclerosis. This may be why some people develop more than one autoimmune disease. The gene that researchers link specifically to RA is an immune system gene named HLA-DR4. This gene is found in about 30 percent of the general population. Among RA patients of European descent, 60 to 70 percent carry this gene.
So, Is RA Hereditary?
Researchers have established that certain genetic markers may increase your risk of developing RA. The genes in question are related to the immune system in general, to chronic inflammation, or with RA in particular. It is important to note that not everyone with these markers develops RA. Not everyone with RA has the markers, either. RA is not hereditary, according to Harvard Medical School.
- Heredity and Arthritis. (2013, May). American College of Rheumatology. Retrieved October 9, 2013, from http://www.rheumatology.org/Practice/Clinical/Patients/Diseases_And_Conditions/Heredity_and_Arthritis
- Patient Education: 10 Frequently Asked Questions about Rheumatoid Arthritis. (n.d.). Harvard Medical School. Retrieved October 9, 2013, from http://cme.med.harvard.edu/cmeups/pdf/patienteducation.pdf
- Rheumatoid Arthritis. (2012, November 19). U.S. Centers for Disease Control and Prevention. Retrieved October 9, 2013, from http://www.cdc.gov/arthritis/basics/rheumatoid.htm
- What is Rheumatoid Arthritis? (n.d.). Arthritis Foundation. Retrieved October 9, 2013, from http://www.arthritis.org/types-what-is-rheumatoid-arthritis.php
- Who Gets Rheumatoid Arthritis? (n.d.). Arthritis Foundation. Retrieved October 9, 2013, http://www.arthritis.org/who-gets-rheumatoid-arthritis.php