Where Does Multiple Sclerosis Come From?

      The application of the “nature versus nurture” dilemma is all-too-familiar to the scientific community. The role of genetics and environment, and which one is more influential, shapes the modern understanding of diseases, especially those with no clear-cut answer, like multiple sclerosis (MS).  

       Multiple sclerosis is a disease that originates in the body’s central nervous system. It damages nerves, impacting a range of functions like vision and coordination.

       As of right now, there is no cure for multiple sclerosis, and understanding of the disease is still progressing. Basic comprehension of most diseases identifies the cause of the symptoms first, and a group of researchers is doing just that, using the science behind twins.

       Whether multiple sclerosis is hereditary or obtained from one’s lifestyle and surroundings is still mostly undetermined. It would be nice to pin the cause of the disease on one big, easy-to-blame “bad guy”, but, factually, MS research is focusing more on how both genes and environment play a role in the emergence of this disease in individuals. It makes sense that both are influential, but to what extent? 

What is multiple sclerosis? Several of its symptoms occur due to nerve damage.

Twins share DNA.

This is pretty well known, and the fact has led to many useful discoveries in the realm of science. Twins, specifically identical twins, share 100% of their DNA. This means that any genetic trait one of the pair possesses, the other will possess the same, or at least, that is how a heritable disease should work. Multiple sclerosis, unlike typical heritable diseases, can actually present in one twin and not another, even when said twins share 100% of their DNA. But how is this possible? How can one twin present symptoms while another is unimpacted?

The answer lies in their environment, but not in the extent to which you think. 

Recent research used identical twins to pinpoint the exact area of difference that causes the onset of multiple sclerosis in one twin and not the other. As expected, their genes were identical, and the subsequent systems of their bodies were as well, except for a small, detected shift in their immune systems. The research found two subsets of the immune system that were different between twins, both of which had been proved, prior, to be relevant to multiple sclerosis. 

It is still unclear as to which environmental factors influenced this change, but the presence of such a distinct discrepancy confirms the belief that multiple sclerosis is not just a genetic disease, and not just an environmental one either. 

It seems strange that identical twins could differ in their body systems, but the finding has ushered in a new comprehension of how multiple sclerosis arises in individuals, and how it is not entirely up to genetics. 

While the “nature versus nurture” debate will surely bounce around the science forum for several more years to come, it is certain that multiple sclerosis research is underway to finally settle the dilemma and, hopefully, finally address the disease that has yet to be cured. The first step is understanding, and slowly but surely, we are making progress. 

Tammy and Terry Haber: identical twins both diagnosed with multiple sclerosis (MS). Today, they run a blog "Twins Coast 2 Coast: Mirror Image MS" where they share their story to inform and inspire others.