Genes and MS
In August 2011, the MS society announced the publication of the results of a global collaboration to investigate the genetic underpinnings of MS. This was a major scientific undertaking that yielded impressive results. Almost 10,000 patients with MS and 17,000 controls without MS were involved in the study. According to a press release put out by the MS Society, the researches “identified 29 new genetic variants associated with MS, and confirmed 23 others previously associated with the disease, verifying a major role for the immune system in the development of MS.”
This is certainly an impressive body of work and will serve to further our understanding of the disease. However, what does this mean for an individual patient with MS, or her family members wishing to know about their potential risk for the disease? Unfortunately, I don’t think these results will translate into anything meaningful for individual patients with MS anytime soon.
There are many diseases, both neurologic and otherwise, where the genetics are almost entirely understood. These include diseases such as Huntington’s disease, cystic fibrosis, and muscular dystrophy. These illnesses are all caused by a defect in a single gene, and in the case of Huntington’s disease, this gene has been known since 1993. Unfortunately, these illnesses are no closer to a cure despite a thorough understanding of their genetic underpinnings. Certain illnesses, caused by a single defective gene, have been aided by the use of gene therapy. But despite some amazing successes, this field has not so far fulfilled the promise many thought it would several years ago.
For a field like MS and many other autoimmune diseases, the finding of over 50 genes linked to the illness makes understanding and putting these discoveries to practical use that much more difficult. Clearly genes play a role in MS, but they are not the major determinant in getting the disease. As I have pointed out in previous posts, if one identical twin has the illness, the chances that his twin will have the illness are only 30%. And since identical twins share the exact same DNA, some unknown factor must who influence who gets the illness and who does not. Moreover, as the MS Society states, “To date, the results of genetics studies in MS do not significantly improve the ability to provide genetic counseling to individuals.”
I have little doubt that in the future, genetic testing will play a powerful role in determining who gets MS and determining who will best respond to certain treatments and who won’t. Unfortunately, no one knows when that day will arrive.