Asked by Danette, Orange, California
Is multiple sclerosis genetic or hereditary? If so, what are the statistics (for example 1 in 1,000)?
Dr. Otis Brawley
Chief Medical Officer,
American Cancer Society
Multiple sclerosis is a disease of the nervous system. It involves demyelination, and nerve degeneration. Demyelination is the removal of the covering of the nerve through an inflammatory response. A good analogy is to think of the nerve as an electrical wire running from the brain to the periphery. Like electrical wires, nerves convey electricity from the brain to muscles to cause movement or from sensors through the body to the brain to cause sensations such as pain, heat, cold or sight. Myelin is the covering of a nerve, just as plastic covers an electrical wire. Demylination, the hallmark of MS, is the removal of that covering. It begins with an inflammatory reaction in the affected nerve causing the nerve to dysfunction and ends as that nerve dies. Persons with MS will lose the function that nerve carried out.
People with severe MS will lose the function of a number of nerves over time and can lose a number of body functions and have phantom pains as a result.
There are several types of MS. Most but not all patients who have MS develop it in their mid 20s to late 30s. For unknown reasons, women are disproportionately affected compared with men. There are some data to suggest that patients with other autoimmune disorders such as type 1 diabetes mellitus, autoimmune thyroid disease and lupus are at increased risk of MS. Women tend to get more of these diseases compared with men as well.
We do not know the cause of the immune system turning on the nerve's insulator. Viral infections may cause this. There is some interest in the Epstein-Barr virus, which causes mononucleosis, as a possible cause of MS. There are also interesting studies that suggest that kids who have a lot of exposure to other kids and their viruses before the age of 6 are at lower risk of MS compared with folks who were relatively isolated from other kids as children.
In the United States the prevalence is about 100 cases per 100,000 Americans. This means about a quarter-million Americans have the disease. There is a geographic variation in the disease. MS is of higher prevalence in Europe (including Russia), southern Canada, the northern United States, New Zealand, and southeast Australia. The prevalence is 1.5 to 2 times greater in the northern United States compared with the southern states.
A Danish study does suggest that relatives of MS patients may be as much as seven times more likely to get the disease compared to people with no known relatives with the disease. This may be the result of common genetics. It could also be caused by common environmental exposures. No one knows for sure. At this time there is no known prevention.
|Most Viewed||Most Emailed||Top Searches|
CNN Comment Policy: CNN encourages you to add a comment to this discussion. You may not post any unlawful, threatening, defamatory, obscene, pornographic or other material that would violate the law. All comments should be relevant to the topic and remain respectful of other authors and commenters. You are solely responsible for your own comments, the consequences of posting those comments, and the consequences of any reliance by you on the comments of others. By submitting your comment, you hereby give CNN the right, but not the obligation, to post, air, edit, exhibit, telecast, cablecast, webcast, re-use, publish, reproduce, use, license, print, distribute or otherwise use your comment(s) and accompanying personal identifying and other information you provide via all forms of media now known or hereafter devised, worldwide, in perpetuity. CNN Privacy Statement.
The information contained on this page does not and is not intended to convey medical advice. CNN is not responsible for any actions or inaction on your part based on the information that is presented here. Please consult a physician or medical professional for personal medical advice or treatment.