Multiple sclerosis (MS) is an autoimmune disease that may run in families. To date, no genetic test can yet reveal whether you or your child will develop the condition, but researchers are making strides in learning about the contributing factors of MS, including the role of genetics and environmental factors.
This article explores the knowns and unknowns of MS genetics, how susceptibility is passed from one generation to the next, the various causes of MS, and how you may be able to lower your risk of developing this condition.
The Problem With MS Genetic Testing
Researchers have found that more than 200 genes appear to contribute to your risk of MS. It may seem like scientists should be able to devise a test based on that, however it’s not that simple. There’s still much about MS that isn’t understood.
What experts do know is:
- MS is an autoimmune disease, which means your immune system mistakenly attack parts of your body as if they were pathogens.
- The targets of these immune system attacks are cells called oligodendrocytes and Schwann cells. Oligodendrocytes and Schwann cells form a protective coating on many nerves called a myelin sheath.
- Damage to the myelin sheath leads to the symptoms of MS and the distinctive brain and spinal cord lesions that are visible on MRI (magnetic resonance imaging).
In some diseases that involve genetics, the responsible genes are defective. They produce abnormal proteins that don’t perform their intended functions properly.
That’s not the case with MS though. Instead, certain genes have minor differences between people with MS and those without it. These differences are called polymorphisms.
You can think of polymorphisms as puzzle pieces that don’t quite fit together the way they should. The cells they produce have subtle differences from the same cells in someone without the polymorphisms.
Thus, people with MS end up with cells that don’t work quite right. These abnormal cells are part of the immune system, brain, and spinal cord.
Experts know that’s not the whole picture. Most people with MS-related polymorphisms never develop the disease. And some people with MS don’t carry any known polymorphisms.
Researchers are still confirming triggers of changes that appear to start the MS disease process. And they’re trying to understand why they have that effect. They believe those triggers are environmental, meaning you encounter them during your life rather than being born with them.
The human genome is incredibly complex. It’s one thing to identify a genetic variation and statistically link it to a disease. Fully interpreting and understanding these variations is far more difficult. In MS, researchers have identified more than 200 variants associated with susceptibility to MS.
That’s an enormous amount of variation to make sense of. Researchers still face gaps in knowledge that may one day be filled in by genetic studies.
MS is autoimmune and tends to run in families, but no genetic test can tell you whether you will develop the condition. More than 200 genes are tied to MS risk, but much is still not understood about them.
Is MS Hereditary?
Multiple sclerosis is not a hereditary disease. Hereditary diseases are caused purely by genetics. If you have the gene, you either have the disease or will develop it eventually.
Because genetics make up part of your MS risk, it is considered a disease with a genetic component. Since people can carry the polymorphisms without ever developing MS, the emphasis is on environmental triggers and how they interact with genetics to cause MS to develop.
Genetic polymorphisms are passed down from parents to children, so MS does run in families. Having a close relative with MS makes it considerably more likely that you’ll have MS one day.
|The Odds of Developing MS|
|No relatives with MS||One in 750|
|Parent with MS||One in 50|
|Sibling with MS||One in 20|
|Identical twin with MS||One in four|
MS doesn’t have one cause—it’s believed to be caused by a combination of genetics and epigenetic changes due to environmental factors.
What Is Epigenetics?
Epigenetics is the study of how your behaviors and environment can cause changes that affect the way your genes work. Unlike genetic changes, epigenetic changes are reversible and do not change your DNA sequence, but they can change how your body reads a DNA sequence.
One of the most important genes linked to MS is from the family of genes called the human leukocyte antigen (HLA) complex. HLA genes affect a protein on the surface of all of your cells.
It’s that protein that tells the immune system that the cell is part of your body rather than something that’ll make you sick. So that may be why the immune system attacks where it does, and that’s what leads to MS symptoms.
The specific HLA gene implicated in MS is called HLA-DRB1. Other major genetic changes known to be associated with MS include:
- CYP27B1: Involved in processing vitamin D
- IL7R: Involved in identifying foreign substances in the body and defending it against disease
- TNFRSF1A: Involved in the cellular process of inflammation
Researchers have identified a range of environmental factors that combine with genetics to trigger MS, including:
- Smoking cigarettes
- Obesity, especially during adolescence
- Hormones, especially female and puberty-related hormones
- Low vitamin D levels
- Climate factors, especially living farther away from the equator
- Night shift work
- Exposure to organic solvents
- Exposure to certain viruses, including the Epstein-Barr virus (EBV)
- Possibly, high salt levels in the diet
Exposures seem to have the biggest impact during adolescence. It’s possible that living far north or south of the equator and working at night contribute to inadequate sun exposure, which leads to low vitamin D levels.
What Is the Epstein-Barr Virus?
The Epstein-Barr virus causes mononucleosis, also called “mono” or the “kissing disease.” It’s a suspect trigger for multiple autoimmune diseases, including MS.
Several of these factors are known to cause epigenetic changes in HLA genes. All of the suspected environmental factors have been shown to influence immune function.
MS isn’t hereditary, but it has a genetic component that combines with environmental factors to trigger the disease. You’re more likely to have MS if a close relative does. Genes linked to MS help the body distinguish its own tissues from foreign invaders like a virus. They’re also involved with vitamin D processing and cellular inflammation.
What You Can Do
While there’s no known way to prevent or delay MS, you may be able to lower your risk by modifying certain environmental factors.
A Healthy Lifestyle
A generally healthy lifestyle may be the most important part of lowering your MS risk. Follow these tips:
- Don’t smoke cigarettes.
- Try to maintain a healthy weight.
- Make sure to get enough vitamin D through diet, sun exposure, or supplements.
- Watch your sodium (salt) intake.
- Avoid exposure to organic solvents.
- Try to avoid working graveyard shifts.
- Avoid viral infection by staying away from sick people, washing your hands frequently, and getting vaccinated.
You may also be able to lower your risk by moving closer to the equator. In the United States, that would mean going south.
Watch for Symptoms
- Optic neuritis: Vision problems and eye pain, usually in just one eye, due to inflammation of the optic nerve
- Facial paralysis: Drooping on one side of your face temporarily
- Ongoing weakness or numbness in a limb: Considered a problem if it goes on for more than a day or so and can make walking difficult
- Ongoing dizziness that’s severe: Often lasts for at least two days
- MS “hug”: A squeezing sensation around your torso
- Bowel and bladder problems: Including constipation, diarrhea, or incontinence
- Pain: Often shooting pains from nerves, especially in the neck, limbs, and feet
- Sexual dysfunction: Changes in arousal and orgasm
While certain symptoms may be more common in the early stages of MS, this disease is highly variable. Don’t assume your symptoms aren’t due to MS just because your early symptoms aren’t typical.
Some studies have identified environmental factors that appear to decrease MS risk. These include:
However, these factors are associated with some increased health risks, so it’s not advisable to pick up these habits or try to be infected by CMV. Focusing on a healthy lifestyle is better for your overall health.
Multiple Sclerosis Doctor Discussion Guide
No genetic tests are available for MS. Changes in 200 genes are linked to the disease, but not everyone with MS has them, and most people with these changes don’t have MS. The changes are polymorphisms, not faulty genes.
MS has a genetic component but isn’t hereditary. You’re at higher risk if you have a close relative with it. Genetics and environment together cause MS. Genes dealing with the immune system and identifying foreign invaders are involved. Environmental factors include smoking, adolescent obesity, hormones, infection with certain viruses, and dietary issues.
A Word From Get Meds Info
While genetic testing can’t currently predict whether you or your child will develop multiple sclerosis, it may someday be able to. Genetic research may lead to better diagnostic tests and treatments, as well.
Until then, talk to your doctor about your risk factors and watch for early symptoms. Above all, focus on living a healthy lifestyle. That’s likely to benefit you in myriad ways, which may include reducing your risk of MS.
Frequently Asked Questions
Can you take a genetic test for MS?
No, genetic testing for MS isn’t yet a reliable predictor of who will develop the disease.
Is MS passed down from parent to child?
The disease itself isn’t directly inherited. However, you can pass a genetic susceptibility to your child. That susceptibility combined with certain environmental triggers (e.g., smoking, certain viruses) could lead to MS.
What environmental factors cause MS?
Environmental factors believed to trigger MS in genetically susceptible people include:
Learn More:The Environment’s Impact on Your Health
- Cigarette smoking
- Adolescent obesity
- Low vitamin D levels
- Living farther from the equator
- Exposure to organic solvents
- Exposure to certain viruses such as the Epstein-Barr virus (EBV)
- Possibly, high levels of dietary salt
How likely are you to develop MS?
Learn More:MS Causes and Risk Factors
- If you don’t have any close relatives with MS, you have between a 0.1% and 0.2% chance of developing it.
- If you have a parent with MS, the risk is about 1.5%.
- If you have a sibling with MS, your risk is around 2.7%.
- If you have an identical twin with MS, your risk is around 30%.
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National Multiple Sclerosis Society. Study question influence of high-salt diet on MS.
Centers for Disease Control and Prevention. What is epigenetics? Updated August 3, 2020.
MedlinePlus. CYP27B1 gene. Updated August 18, 2020.
MedlinePlus. IL7R gene. Updated August 18, 2020.
MedlinePlus. TNFRSF1A gene. Updated August 18, 2020.
Olsson T, Barcellos LF, Alfredsson L. Interactions between genetic, lifestyle and environmental risk factors for multiple sclerosis. Nat Rev Neurol. 2017;13(1):25-36. doi:10.1038/nrneurol.2016.187
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Rush University Medical Center. Early signs of multiple sclerosis.
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