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Understanding how and when MS occurs in our bodies remains a research focus, but there are some clear trends that are important to know about. MS can occur at any time, particularly between 20 to 50 years of age, but children and older adults can also get MS. Women are three times more likely to get MS than men.


Is MS genetic? Your genes are a blueprint for what makes you who you are. From hair colour through to predisposition for certain diseases, your genetics work like an instruction book for your body.

Genes can also change over time, either spontaneously or through being inherited, which is why some people ask if MS is hereditary.

People with MS may have slight gene variations, called polymorphisms. These are healthy genes that don’t fit together well. This means the way the cell works is altered, in particular with the brain, immune system and spinal cord.

The Human Leukocyte Antigen (HLA) gene – also known as Major Histocompatibility Complex or MHC – can play a role in a person developing MS. The HLA gene can be found on the surface of all body cells. It signals your body’s immune system to confirm if a cell is part of your body and therefore shouldn’t be attacked.

If something alters the HLA gene, your body may not be able to protect itself from attacks, which can lead to developing MS.


One theory is that a virus may play a role in developing MS. If a person has a virus (that’s either active or dormant in the body), it could disturb the immune system or incorrectly trigger an auto-immune reaction.

While it’s unlikely there’s a multiple sclerosis virus, common viruses, such as measles or the common herpes virus, could act as a trigger for MS.

Having a virus could activate white blood cells (lymphocytes) in the bloodstream, which could enter the brain and weaken its defense mechanisms. If these cells enter the brain, it could make the body attack and destroy myelin (which protects nerve cells used to carry messages from your brain and around your body.)

Other potential factors

Other lifestyle factors and habits have been linked to MS.

These include:

  • Smoking – cigarette smoke damages cells that line the lungs, which could make the blood-brain barrier weaker.
  • Geographic location – MS is more common in countries further away from the equator.
  • Weight – Being overweight or obese may increase your chance of developing MS.

Learn more about MS

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