Is Multiple Sclerosis Hereditary?

Other Factors, Besides Your DNA, Are at Play

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Multiple sclerosis (MS) is not a directly inherited disease. This implies that MS is not definitively passed down through generations of a family (for example, you will not automatically develop MS because your mom, dad, or sibling has it).

That said, there is an inherited component to MS. Some people are more likely to develop MS than others, based on their genetic makeup.

Statistics and MS

Looking at statistics can hopefully help you better understand the role genes play in increasing your or your loved one's risk for having MS.

Consider the following:

  • In the general population, a person has a 0.1% to 0.2% chance of developing MS. This means that approximately 1 in 500 to 750 people will get MS in their lifetime.
  • A person's risk increases to 2% to 4% if they have a sibling with MS.
  • Children of people with MS have an even higher risk of developing MS at 3% to 5%.
  • The highest risk of developing MS comes with being an identical twin of a person with MS. In these cases, the risk is around 30%.

Key Point

The fact that an identical twin of someone with MS will not always also develop MS (even though they share the same DNA) drives home the point that other factors must be at play besides genes.

Genetic Studies and MS

Besides family studies and statistics, experts are looking closely at the specific genes linked to MS pathogenesis.

In a large study of over 47,000 people with MS, researchers identified over 230 gene variants associated with an increased chance of developing MS.

A genetic variant is another word for a mutated gene, meaning there is a change in the DNA sequence within the gene.

More specifically, this study found 32 genetic variants within the major histocompatibility complex (MHC), as well as one genetic variant on chromosome X (the first "MS gene" found on a sex chromosome). Two hundred genetic variants were found outside of the MHC.

Major Histocompatibility Complex (MHC)

For a while now, experts have linked MS to genes in the MHC region. The MHC is a sophisticated set of genes that codes for proteins that help the immune system recognize foreign substances in the body.

If one or more of these genes is mutated, the immune system may misguidedly bind to (and promote an attack) against normal, healthy substances (like the proteins that compose the myelin sheath, as in the case of MS).

Besides inappropriate protein-binding in MS, research suggests that genes within the MHC region may influence the severity of a person's MS and interact with potential environmental factors, notably vitamin D.

B Cells

The above study also found an excess of these MS-related genetic variants in B cells. This finding implicates B cells (a type of immune system cell) as perhaps being involved in the earliest stages of MS development.

Interestingly, novel MS therapies, most notably Ocrevus (ocrelizumab), are targeting B cells.

Beyond Your Genes

While your genes may predispose you, or make you more vulnerable, to developing MS, certain factors within your environment must be present to trigger the disease to ultimately manifest.

Even though the precise factors have not been all sorted out yet, researchers suspect the following culprits may be involved:

Bottom Line

It is likely the unique and complex interplay between your genes and your environment that determine whether or not you will develop MS.

A Word From Verywell

The take-home message here is that while not directed inherited, genetics do play a role in MS development, and this is supported by both genetic and family studies.

As of right now, there is no standard genetic test for MS. Even if there was though, it's important to keep in mind that carrying certain "MS-related genes" only makes you more susceptible to developing the disease. Other factors play a role too.

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