Multiple sclerosis: is the disease hereditary?

In France, approximately 110,000 people suffer from multiple sclerosis (MS). “It is a pathology that develops more in young adults with a peak of appearance around the age of 30.“underlines Dr. Céline Louapre, neurologist.

Multiple sclerosis, a pathology “which affects the central nervous system, i.e. the brain, spinal cord, cerebellum, brainstem and optic nervess”, can manifest itself through a wide variety of symptoms:

• Motor disorders: difficulty walking or loss of strength, for example,
• Sensitivity disorders: tingling, numbness, pain… in a limb or even in half of the body,
• Balance disorders: dizziness, movement coordination problems, etc.
• Visual disturbances: loss of vision in one eye or double vision, for example,
• Cognitive disorders: difficulties with attention, concentration, memory, fatigue…

What causes multiple sclerosis (MS)?

“For multiple sclerosis, it is complicated to speak of “causes”, in particular because many of them have not yet been determined.explains Dr. Céline Louapre. We prefer to speak of “susceptibility factors”: these are elements that increase the risk of developing the disease.”

Attention ! Having a risk factor for multiple sclerosis absolutely does not mean that you will catch the disease! “A person who smokes will have an increased risk of developing lung cancer because smoking is a risk factor for this disease. But that does not mean that all smokers systematically develop lung cancer!” illustrates the neurologist.

In addition, the epidemiological studies are formal: the different susceptibility factors for MS “have only a modest impact on the risk of developing the diseaseThey are, however, cumulative: the more susceptibility factors there are, the greater the risk of MS.

The susceptibility factors for multiple sclerosis are primarily environmental. We can mention in particular:

• Epstein-Barr virus infection,
• smoking,
• Vitamin D deficiency,
• Geographic location: MS is more common towards the poles.

There are also genetic susceptibility factors: “to date, 200 genetic variants that could potentially increase the risk of MS have been identified: half of them are located in genes that code for the immune system“explains Dr. Céline Louapre.

Is multiple sclerosis (MS) inherited?

First thing to know:90% of patients with multiple sclerosis have no family history, even 2nd or 3rd degree!“says the neurologist. In the vast majority of cases, this pathology is therefore random.

Nevertheless, parents with multiple sclerosis actually have a higher than average risk of giving birth to a child with this disease. So, when both parents have MS, the child is at between 10% and 30% risk ; when only one of the two parents is affected, the risk is between 1% and 2%. As a reminder, when both parents are healthy, the risk of giving birth to a child with MS is around 0.1%.

“Multiple sclerosis cannot be described as a “hereditary disease”: indeed, unlike Huntington’s disease for example, this pathology is not transmitted systematically from parent to child when certain “genetic parameters” are met.explains Dr. Céline Louapre. The child can, on the other hand, inherit genetic susceptibility factors.“

To date, there is no test that would “detect” multiple sclerosis during pregnancy in the unborn child. “It wouldn’t be relevantreacts the neurologist. MS is a complex and multi-factorial disease: the genetic susceptibility factors are numerous, different depending on the patient and in no way predictive!“

Thanks to Dr. Céline Louapre, neurologist and director of the clinical investigation center at theBrain Institute (ICM).

Source :Inserm