Genetics apparently does play a role in the development and course of multiple sclerosis (MS), say scientists who released new research about a cluster of genes they focused on that they say plays a key part in the disease.1
A Unique Role in MS
No other genes except for this one cluster has "a similar overall influence on MS genetics," explained Jonathan Haines, PhD, of Vanderbilt University in Nashville, who headed the study and presented the findings at a meeting of the American Neurological Association earlier this year.
Haines suggested that these findings have profound implications for the future direction of MS genetics research.
Genes that Recognize the Body's Cells
Scientists call this group of genes the major histocompatibility complex (MHC). They play a critical role in the recognition of cells in the body as belonging to the body as opposed to cells found on bacteria or other disease-causing organisms.
Thus, when this system of recognition breaks down, the immune system may not recognize that certain cells are those of the body, and go after them as if they were the source of disease. Experts have theorized that MS is an autoimmune disease, in which the immune system goes after healthy tissue in the central nervous system, eventually destroying it and causing the symptoms that are seen in the illness. Depending on what nerve fibers are damaged in the central nervous system, the symptoms of MS can vary.2
More specifically, the body attacks and destroys cells that make myelin, a fatty substance that insulates nerve fibers in the central nervous system.
Researchers also believe that some genetic variations that occur in the major histocompatibility complex may make people more susceptible to the as yet unknown environmental triggers that spark the onset of MS.
Researchers: Other Studies Were Weakly Designed
Haines, head of the Center for Human Genome Research at Vanderbilt, is one of hundreds of scientists who have collected genetic information on 730 families with more than one case of MS in four countries around the world, including the United States. While previous studies have implied that the MHC plays a role in the development of MS, researchers have also suggested that other areas of a person's genome—the collective grouping of all of a person's genes in the body—may also harbor genes that boosts a person's risk of developing the disease.3,4
Haines suggests these studies didn't involve enough patients to make definitive conclusions. "This is the largest genetic linkage study on MS, and the first to be done using the latest technology, which provides very detailed coverage of the entire human genome," Haines said. "Other genes may still play an important role in MS, but finding them will require using new genomic techniques."
1. American Neurological Association 130th Annual Meeting. 2005 September 25-28. San Diego, CA.
2. Multiple Sclerosis Foundation. MS Info. Available at: http://www.msfacts.org/info/info_faq.html. Accessed November 4, 2005.
3. Dyment DA, Ebers GC, Sadovnick AD. Genetics of multiple sclerosis. Lancet Neurol 2004 Feb;3(2):104-10.
4. Tienari PJ, Terwilliger JD, Ott J, Palo J, Peltonen L. Two-locus linkage analysis in multiple sclerosis (MS). Genomics 1994 Jan 15;19(2):320-5.
John Martin is a long-time health journalist and an editor for CuraScript. His credits include overseeing health news coverage for the website of Fox Television's The Health Network, and articles for the New York Post and other consumer and trade publications.
