Is Multiple Sclerosis Genetic?

Perhaps multiple sclerosis (MS) has touched your life personally through your own diagnosis or a loved one developing the condition. Alternatively, you may have no personal experience with the disease but are interested in learning more about it. 

Being an autoimmune disease, MS occurs when the immune system attacks the myelin sheath protecting neurons in the brain, as explained by Mount Sinai. As a result, someone with MS can experience symptoms like muscle weakness, dizziness, balance and coordination problems, trouble walking, vision loss, and disorganized speech. A wheelchair is often used to help individuals with MS move around. 

There's no known cure for the condition, and receiving a diagnosis of MS could feel earth-shattering to the person being diagnosed. Both an individual's physical and mental health can be adversely affected by MS. In about half of all MS patients, depression is a concern while living with the disease, as noted by Cleveland Clinic

Those with MS may wonder what factors could have contributed to their disease. According to UK's National Health Service, researchers have identified a history of smoking, insufficient sunlight exposure, and infections like the Epstein-Barr virus to be some potential risk factors for developing MS. In addition, the chances of a woman developing MS are 2 to 3 times greater than a man's. 

Genetic factors also seem to be at play in the development of the disease. Let's dive deeper into how a family history of MS may increase someone's chances of also being affected by the disease. 

Can multiple sclerosis be inherited?

Although genes appear to play a role in the development of multiple sclerosis (MS), the National Multiple Sclerosis Society explains that it's not a heritable disease, and it doesn't pass down from generation to generation like hair color does. However, having a family member with MS can increase someone's genetic risk of the disease in some cases. According to Healthline, the average person has a 0.1% to 0.3% chance of developing MS. Having a parent or sibling with MS increases the risk to approximately 3%, but most parents with MS will not pass down the disease to their children, as noted by MS Focus Magazine

Studies conducted on identical twins have suggested that if one twin develops MS, there's a 1 in 4 chance the other twin will develop the disease. These studies are particularly insightful in answering the question of heritability because they suggest that MS is partly genetic, but not completely. If one identical twin had MS, the other twin would have to be 100% likely to develop it if MS was truly a genetic disease, as MS Focus Magazine points out.

Like many other medical conditions, researchers believe MS to be a manifestation of both genetic and environmental factors. For example, some evidence suggests that people who live in geographical areas further away from the equator may be more susceptible to developing MS, as explained by the National Multiple Sclerosis Society. 

Which genes are associated with multiple sclerosis?

Multiple sclerosis (MS) isn't hereditary, but genes are still suspected to contribute to its progression. Researchers are actively investigating which of these genes are involved in the development of MS in order to better understand the disease and create successful treatments. According to the MS Society, more than 200 genes have been identified as being associated with MS. In particular, the risk of MS appears to be higher in those who carry genes related to vitamin D deficiency. Higher vitamin D levels have been found to increase the activity of one gene associated with MS. In light of these findings, it's believed that getting enough vitamin D through sunlight, your diet, and supplements may be a protective factor against developing MS, as noted by the Mayo Clinic

One 2022 study published in the Journal of Neurology discovered a potential relationship between a genetic predisposition to elevated body mass index (BMI) in childhood and future MS development. Their results suggested that individuals who were genetically predisposed to a higher BMI in childhood may be more susceptible to developing MS, particularly if their BMI remained consistently high throughout adolescence and young adulthood. 

One important gene that appears to be significantly connected to MS is HLA-DRB1 (per MedlinePlus). Another gene, IL-7R, is also associated with the condition. It's interesting to note that both of these genes play important roles in immune system function, which may be relevant to how the immune system reacts during MS attacks.