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.
Knowns
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.
Unknowns
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.
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.
Genetic Factors
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 DIL7R: Involved in identifying foreign substances in the body and defending it against diseaseTNFRSF1A: Involved in the cellular process of inflammation
Environmental Factors
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.
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.
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
Early diagnosis and treatment are believed to slow the progression of MS, so being aware of early symptoms is important. Some common early symptoms include:
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
Some studies have identified environmental factors that appear to decrease MS risk. These include:
Cytomegalovirus (CMV) infection Oral tobacco use (“chewing”) Alcohol use Coffee consumption
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.
Summary
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.
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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 Verywell
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.
Cigarette smoking Adolescent obesityHormonesLow vitamin D levelsLiving farther from the equatorExposure to organic solventsExposure to certain viruses such as the Epstein-Barr virus (EBV)Possibly, high levels of dietary salt
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