Is Multiple Sclerosis (MS) Hereditary?

Multiple sclerosis (MS) is an inflammatory disease in which your immune system attacks your central nervous system, including your brain, spinal cord, and optic nerve, destroying cells, tissue, and protective nerve coverings called myelin. 

Although your genes play a role in whether you develop MS—and the risk is higher if other people in your family also have it—MS is not a hereditary disease passed down directly from one family member to another.  

Hereditary diseases are genetic changes, or mutations, passed down from parent to child. For example, cystic fibrosis is a hereditary disease caused by the mutation of a specific gene called CFTR—and if you inherit a CFTR gene from both of your parents, you will have cystic fibrosis.

Multiple sclerosis is not a hereditary disease, even though genetics play a role.

For example, researchers have identified more than 200 genes associated with an increased risk of MS. But being born with genes associated with a risk of MS is only a piece of the puzzle: You need a combination of genetics and environmental factors to develop the disorder. 

If you’re born with genes that allow for the development of MS under the right circumstances, exposure to some factors or circumstances may trigger the onset of MS. Many people are born with a genetic predisposition and never develop MS.

What’s the Risk If a Family Member Has MS?

Although MS isn’t hereditary, it does tend to run in families. Roughly 15-20% of people with the disease have a family history of it.

The average person in the U.S. has a less-than-1% chance of getting MS, but that risk increases for first-degree relatives:

• There’s a 2% risk for children of parents with MS.
• There’s a 4% risk for siblings and nonidentical twins of someone with MS.
• There’s a 31% risk for the other identical twin when one twin is diagnosed with MS.

In addition to some inherited genes, many factors are associated with an increased risk of MS. These include:

• Epstein-Barr virus (EBV): EBV is the virus that causes infectious mononucleosis, or mono. Experts don’t know why people who have been infected with EBV—especially as adolescents or adults—have a higher risk of MS than people infected as kids or not at all. It may be because the virus triggers a heightened inflammatory response by the immune system. 
• Low vitamin D: People with low vitamin D levels in their blood are at a higher risk for MS, likely because of how important it is for healthy immune function. Most of our vitamin D comes from sun exposure. Researchers have found MS is less common in areas closer to the equator, where there is stronger sunlight for more months of the year.
• Obesity: Having obesity in adolescence and young adulthood may increase the risk of MS later in life, especially in girls. Obesity causes inflammation in the body, which may trigger MS in people with a genetic risk. Research suggests that adolescents with a body mass index (BMI) of 27 or higher are most at risk.  
• Smoking: Smoking is connected to a higher risk of many health conditions, including inflammatory and autoimmune diseases. Smoking increases your risk of MS, and it may also worsen the severity of your symptoms and speed up disease progression.  

If you’re at risk for multiple sclerosis, it may help to know some of the first signs of MS so you can recognize them as soon as possible. The symptoms of MS often begin in young adulthood, between the ages of 20 and 40. Symptoms of MS may include:

• Vision changes such as double vision and eye pain
• Muscle weakness, stiffness, pain, or spasms
• Tingling or numbness in your arms, legs, face, or torso
• Difficulty with balance
• Bladder symptoms, including incontinence
• Dizziness
• Fatigue
• Mood changes
• Difficulty concentrating or remembering

Many of the symptoms overlap with other conditions, so diagnosing MS can be challenging. There is no single test that can confirm you have it. Rather, doctors rely on a combination of strategies, including physical exams, blood tests, spinal fluid testing, and magnetic resonance imaging (MRI) to diagnose or rule out other causes.  

Any change in your neurological health warrants an appointment with a healthcare provider. It’s a good idea to see a primary care provider first to rule out other, more common causes of your symptoms. They may refer you to a neurologist (a specialist in the nervous system) for more evaluation or treatment as needed.

A delay in diagnosing MS also means a delay in treating MS, which can make your symptoms more difficult to manage. Serious and permanent nerve damage can happen even in the early stages of the disease.

Early detection means you can access treatments that are available to help control symptoms and limit the damage to your central nervous system if you have MS.

Multiple sclerosis (MS) is an autoimmune disease that affects your nervous system, damaging your nerves and their protective coverings. MS is caused by a combination of genes and environmental factors, but it’s not an inherited disease.

Your risk for developing MS is higher if you have other risk factors too, such as a parent with MS, Epstein-Barr virus infection, obesity, or low vitamin D levels.