Although multiple sclerosis was described by Charcot more than a century and a half ago, the causes of this disease of the central nervous system are still unknown.
Genetic factors
Multiple sclerosis (MS) is not an inherited disease. It is a multifactorial condition. Some environmental factors have now been identified without a clear causal relationship. Similarly, genetic predisposition may also be present. The latter can be defined as a combination of genetic variants, which confers a greater risk of developing the disease. It is considered that this alone is not sufficient for the disease to appear, but that it is a breeding ground for its development. It should be noted that most of the genetic variants identified are associated with so-called “immune” genes, that is, genes involved in inflammation.
Epidemiological studies have not been able to identify with any certainty an environmental factor responsible for the outbreak of the disease. Vitamin D deficiency could be a triggering factor, but its implication has not yet been conclusively proven. Many viruses have also been studied with the hypothesis that a viral infection acquired in early childhood may cause illness in genetically susceptible individuals.
The link between multiple sclerosis and infection with Epstein-Barr virus has long been suspected. Very recently, an American study has provided important new information on this association. Epstein-Barr virus belongs to the herpes virus family. Mostly contracted asymptomatically in childhood, it is also responsible for infectious mononucleosis or “kissing disease.” The Epstein-Barr virus is widespread in the general population, with an estimated 90% of adults having had contact with the virus. This infection appears to be a necessary but not sufficient condition for the development of multiple sclerosis. The vast majority of the population infected with the Epstein-Barr virus will never develop multiple sclerosis.
No link between vaccination and multiple sclerosis
Vaccines have long been implicated in the development of multiple sclerosis (MS) and have been the subject of large-scale epidemiological studies. Two million girls vaccinated against HPV were followed over several years in a study conducted by the National Agency for the Safety of Medicines and Health Products. The conclusion of this study is that the occurrence of multiple sclerosis in these girls is no more frequent than in the general population. Several studies on the relationship between the hepatitis B vaccine and the occurrence of multiple sclerosis have reached the same conclusions.
At Paris Brain Institute
The International Multiple Sclerosis Genetics Consortium (IMSGC) involving a research team from Paris Brain Institute published in 2019 a scientific article in the journal Science bringing the number of genetic variants predisposed to multiple sclerosis to 233. The study involved 47,429 patients and 68,374 controls. These findings confirm that multiple sclerosis is the result of a dysfunctional immune system and open the door to functional research into the causes of the disease.
