When people age gracefully and live a long life, many often credit their lifestyle choices and “good genes.” Similarly, when people fall ill to a serious disease, inherited “bad genes” can be a cause of blame. But what about a variable disease like arthritis?
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“It’s very likely there is a genetic component to arthritis,” says rheumatologist Abrahim Syed, MD. “The exact role of genetics is still not well known.”
Yet it’s important to note that most diseases aren’t determined by genetic makeup alone. Many individuals inherit genes that make them more likely to acquire a certain disease.
The most common type: Osteoarthritis
Easily the most common form of arthritis, osteoarthritis can cause inflammation and damage to joints when cartilage that covers the ends of bones degenerate.
There are hereditary forms of osteoarthritis that are caused by mutations in genes for collagen.
This type of osteoarthritis can first appear at a young age, quickly causing severe damage, though not very common. Around 40 to 65% of osteoarthritis has a genetic component, with a stronger link for hand and hip cases.
Dr. Syed assures that there is not a singular gene that causes cases of osteoarthritis. “Multiple genes are involved,” he comments. “The influence of other factors, such as obesity, joint injuries, aging and joint anatomy, also is quite substantial.”
An autoimmune type: Rheumatoid arthritis
Genetic factors are more strongly linked to cases of rheumatoid arthritis (RA), however. Classified as an autoimmune disease, RA primarily targets the lining of joints, mistakenly attacking the healthy tissue instead of damaged tissue.
Some environmental factors — such as infection, injury or smoking — can trigger immune system response in genetically susceptible people. In addition, there are over 100 genes that may be linked to RA and the damaging effects on the immune system.
A type affecting the spine: Ankylosing spondylitis
This type of arthritis causes inflammation in the spinal joints. Approximately 90% of patients with AS carry a gene called HLA-B27.
Detected by a laboratory test, Dr. Syed warns that “A positive test by itself is not diagnostic. Not everyone with the gene gets AS and some people without the gene develop it.”
Family history also plays a role in a person’s susceptibility. People who have a family member with AS are more likely to develop the disease compared with those without the gene and no family history.
Looking beyond inheritance
A future of more personalized medicine can be achieved when we look to understand the genetics contributing to the cause of disease.
“Eventually, we may be able to modify genetic risk, as opposed to treating the result of genes on inflammatory effects,” explains Dr. Syed.
This article originally appeared in Cleveland Clinic Arthritis Advisor.