I often get asked this question. Mostly by worried parents, one of whom has MS, and who are concerned about their children.
If one defines a hereditary disease as a disease that is due to a clearly defined defect in the human genome, which is inherited according to a certain pattern, then the answer is clearly “no”.
But it’s not uncommon for someone to interject “but my sister/mother/aunt also has MS – the disease must be inherited”. And indeed, this is an observation that can sometimes be made. MS often occurs sporadically, but there are families where there is a cluster of MS cases. And this observation is also a reason why it is assumed that genetic factors play a role in the development of the disease, but not the only one, as with a classic hereditary disease.
The risk of developing MS in Germany is about 1:700. If there is a family predisposition, e.g., a parent suffers from MS, the risk increases by about a factor of 3, so to about 1:200. This is a higher risk, but the probability of developing MS is still relatively low. Therefore, a familial burden of MS is no reason to reconsider family planning or to consider not having children at all. And it is certainly no reason to subject children of parents with MS to an MRI examination as a preventive measure. One must clearly advise against this.
It is very interesting that in identical twins, who are genetically identical, both do not necessarily develop MS. The risk for the second twin to develop MS if the first one has been diagnosed with MS is “only” 30%. So despite complete genetic equality, 2/3 of identical twin siblings do not get MS.
This is a pretty strong argument that genetic factors alone are not the cause of MS. There must be additional causative factors. And here so-called environmental factors are held responsible. However, one should not misunderstand the term environmental factors: Many MS patients blame pollution and unhealthy lifestyles in modern industrial society for the disease. But this is too short-sighted with regard to MS, because the disease existed long before industrialization and it can also be found in developing countries.
Environmental factors more accurately describe certain geographical and climatic conditions (i.e., where we live in the world) and certain infectious diseases that we contract during our lives. The current hypothesis of the development of MS assumes that in a genetically predisposed individual – triggered by an infectious disease in adolescence – there is a misdirection of the immune system that leads to the body’s own immune cells recognizing and attacking their own nerve tissue as foreign.
It can be assumed that this does not have to be a specific infectious disease that causes this misdirection. Although certain viruses have repeatedly been held responsible for triggering MS in the past – currently everything revolves around the Epstein-Barr virus, the causative agent of mononucleosis – but ultimately probably any pathogen, if it encounters a person predisposed to autoimmune diseases, can trigger such a disease.
Therefore, I am firmly convinced that we will never identify “the MS pathogen” and that MS is caused by the random convergence of several factors. I’m pretty sure that it will never be clarified for the individual why he and not his neighbor has developed MS.
This ultimately not fully explained cause of MS makes many patients insecure. Not infrequently this also leads to people attributing certain causes such as the birth of a child, a traumatic event in the family, a vaccination…
Ultimately, however, it is probably just a coincidence…
With kind regards
Your Mathias Mäurer
