Is Multiple Sclerosis Hereditary, or Do Environmental Factors Play a Role?

·5 min read
Photo credit: koto_feja - Getty Images
Photo credit: koto_feja - Getty Images

Multiple sclerosis is an autoimmune condition where, for reasons scientists are still trying to understand, your body’s immune system suddenly attacks the coating covering the nerves in your brain and spinal cord.

“If you think of the nerve cells as wires, the myelin is like the insulation protecting those wires,” explains Josef Gutman, M.D, a neurologist and director of the NYU Long Island Comprehensive Multiple Sclerosis Center. Inflammation and other immune damage to the nerves’ outer coating can disrupt the firing of nerve cells, leading to a wide range of symptoms from muscle weakness to vision problems.

Scientists have not found one true cause behind multiple sclerosis. But what is known is that there is a genetic factor that could influence your disease risk.

How do your genes affect multiple sclerosis?

There is no single gene that directly causes MS

There are many genes—as much as 233—that each have their own small contribution to multiple sclerosis. “There’s a lot of research looking at what alleles, pieces of gene, in people with multiple sclerosis have that aren’t seen in the general population that could make them susceptible to the disease,” adds says Mary Ann Picone, M.D., a neurologist specializing in multiple sclerosis at Holy Name Medical Center.

Dr. Gutman says the ones most relevant to the development of multiple sclerosis are those involved in regulating the immune system. In other words, genes that regulate what your immune system will target versus not target. Indeed, research shows that some of these genes—HLA-DRB1 and the HLA-DRB1*15:01—are involved in innate immunity, the first line of defense when a threat is present in the body, and contributes to the progression of multiple sclerosis.

Your genes play a small role in getting MS

Having a family history of multiple sclerosis can also elevate your risk of the disease, although it’s not something that’s passed down from parent to child. What’s more, even if a relative has multiple sclerosis, Dr. Gutman says the increased risk is very small in the grand scheme of things. “Compare it to sickle cell anemia where if a parent has sickle cell disease, you have a 25% chance of being a carrier, sometimes 50% depending on the other parent.”

“It’s one of the ways we know that multiple sclerosis is an autoimmune disease unlike Alzheimer's, where it's more of a neurodegenerative disease with a weaker genetic link,” adds Sharon Stoll, D.O., a neurologist specializing in multiple sclerosis and neuroimmunology at Yale School of Medicine.

What’s your genetic risk?

You have an estimated 1 in 67 chance (1.5%) of getting multiple sclerosis if mother or father have it as well. A brother or sister with multiple sclerosis translates to a 1 in 37 (2.7%) chance of developing it yourself.

In identical twins whose genes are 100% identical, if one developed multiple sclerosis, the chances of the other getting it is 25%. “If this was a strictly genetic condition, one condition in one twin would mean a 100% chance of getting it for the other,” explains Dr. Gutman.

To put it in perspective, Dr. Gutman says having multiple sclerosis from a close relative makes you 20 times higher than the general population—raising your overall risk to 2% and a 98% chance you won’t ever develop it. “Again, there is a genetic contribution, but by far the most risk is non-genetic.”

Other risk factors for MS

Genetic is only part of the story. There are environmental triggers that can increase your risk for multiple sclerosis. These include:

  • Epstein-Barr infection

  • Low vitamin D levels

  • Age

  • Being of the female gender

  • Having other autoimmune diseases

  • Smoking

  • Obesity

How do you treat multiple sclerosis?

Experts agree you should see your primary care doctor (PCP) if you feel pain or any unusual bodily sensations. Your PCP can assess for symptoms affiliated with multiple sclerosis such as muscle weakness, numbness in the body, vision problems and refer you to a neurologist for further testing.

Though Dr. Gutman says there is no need for people with family members that have multiple sclerosis to undergo preventative routine screening unless you start to experience some concerning and unexplainable symptoms.

There is no single diagnostic test for multiple sclerosis. Instead, a neurologist may have you undergo several imaging scans, blood tests, and a physical exam to rule out other diseases. Dr. Stoll says that because multiple sclerosis has a genetic component, you’ll likely be asked if you have a family history of either autoimmune diseases or a personal history of autoimmune diseases.

Dr. Picone says there are over 20 FDA-approved treatments for multiple sclerosis, and the earlier you start the greater the chance for a good outcome. If you receive an official multiple sclerosis diagnosis, Dr. Stoll says your doctor will likely prescribe you with immunosuppressant medications intended to weaken the immune system partially to prevent further myelin damage. The second medication option are immunomodulators that manipulate immune function and how they respond to a potential threat. Other treatments may involve injectable medications, oral therapies, and other intravenous therapies.

“These are very effective and can go a long way towards preventing relapses, slowing down the progression, and helping you live as normal a life as possible,” says Dr. Picone.

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