The Genetics of Multiple Sclerosis

Immune System Genes Linked to MS

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Your genes are an important factor in whether or not you are at risk for developing MS, as supported by both family and scientific studies.

Family Studies as Proof that Genes Play a Role in MS

In the general population, there is a 1 in 750 chance (0.1 percent) chance that a person will develop MS. But the identical twin of a person with MS has approximately a 25 to 40 percent chance of developing MS, and the sibling or child of a person with MS has a 3 to 5 percent chance.

Scientific Studies as Proof that Genes Play a Role in MS

A 2007 study published in the New England Journal of Medicine found a new genetic risk factor for multiple sclerosis (MS). The study shows that people who have certain variations of two different genes involved in the immune system (IL7RA and IL2RA) are more likely to have MS than people without these mutations.

IZ7RA and IL2RA are proteins that guide the actions of one type of immune cell (T cells). As genes control how proteins are made in the body, changes in protein type represent a difference in genetics.

The MS-related version of the protein may contribute to MS by guiding those immune cells to attack the nervous system, which leads to demyelination and lesions on the brain and spinal cord. This damage, in turn, causes the huge variety of MS symptoms. Interestingly, IL2R mutations have been associated with type 1 diabetes and Graves’ disease, also autoimmune disorders.

A number of other studies have supported a link between MS and the genes that control a person's immune system. The tricky part is that there are likely a vast number of genetic changes, estimated to be 50 to 100 by the National MS Society, that determine a person's risk of developing MS and if they do develop MS, how severe it is.

Analyzing the MS genetic data is complicated and time-consuming, but worthwhile, especially if it can better tailor MS therapies. 

Bottom Line

It's important to understand that while genes do play an important role in the development of MS and potentially the course it follows, they are not everything. In other words, MS is not a directly inherited illness, so there is no guarantee that you will or will not get it based on your family history (or your individual genetic code).

Instead, the manner in which MS develops and manifests in a person is likely complex, involving a dynamic between a person's genes and their environment. For example, a series of genetic changes may make a person more vulnerable to developing MS when exposed to a certain environmental trigger, like a virus (although, we do not know those precise triggers yet).

As of right now, doctors do not do genetic testing on people with MS or family members of those with MS. But as MS genetic research advances (which it is very quickly), treatment may vary based on a person's individual genetic makeup.

 

Sources:

Gourraud, P.A., Harbo, H.F., Hauser, S.L., & Baranzini, S.E. (2012). The genetics of multiple sclerosis: an up-to-date review. Immunological Reviews, Jul;248(1):87-103.

International Multiple Sclerosis Genetics Consortium, et al. (2007). Risk alleles for multiple sclerosis identified by a genomewide study. New England Journal of Medicine, Aug 30;357(9):851-62.

National MS Society. Who Gets MS? (Epidemiology)

National MS Society. The Basic Facts: Genetics. 

Sadovnick, A.D., et al. (1993). A population-based study of multiple sclerosis in twins: update. Annals  of Neurology, Mar;33(3):281-5.

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