1) We estimate the narrow sense heritability of Multiple Sclerosis to be a low number for a few reasons. First, an exact cause has not been identified for MS. Second, it is unknown how much of the progression of the disease is due to the environment, and how much is due to heredity. Given these two points, it would be impossible to calculate an exact number for narrow-sense heritability. However, one study from 1998 suggested genetic heritability is high and includes more genes than originally suggested. Therefore, we believe the h2 value will be somewhat higher, anywhere from 75-85%. This information was gathered from a Brain, A Journal of Neurology article entitled "The genetics of multiple sclerosis: principles, background and updated results of the United Kingdom systematic genome screen" by J Chataway.
Given the high h2 value we chose to use, selection would have a large influence on MS. Along with a high h2 value comes a high degree of genetic variation, thus selection will occur at a higher rate.
2) In order to answer the question, what effect will inbreeding have on multiple sclerosis, we must first know the method of how one comes to be affected by this disease. As of right now, this is unknown. However, studies have shown that women are more affected than men. Also, families that already have someone with the disease are more likely to see another individual with multiple sclerosis. Knowing this, it can be inferred there must be a genetic component to MS that contributes. Therefore, inbreeding can be assumed to have an increased effect upon the prevalence of multiple sclerosis.
As stated above, multiple sclerosis seems to affect women more so than men. This could be a result from the role of the maternal effects upon the egg. Also, women are able to have children before the effects of MS are noticeable so many offspring could be produced before it is known the mother has MS. This would increase the number of people that carry the potential alleles. If inbreeding were to happen these alleles would more frequently come into contact with each other, thus increasing the frequency of the multiple sclerosis phenotype.
Comparing Nerve Cells
Differences in healthy nerve cells (left) and nerve cells affected with MS (right)
2 comments:
due to lack of views by outside sources of our groups Multiple Sclerosis blog, we felt the need to shed some light on our own post. Simply stated, this was a superb effort on our part. Well done. Keep up the good work.
You said it. There is now no need for me to leave a comment. But I will. You guys did an excellent job of speculating and reasoning through the limited information that is available on the causative agents of MS.
The final blog entry will simply involve logging in your group's progress on the project before your presentation.
Well done. Keep up the good work.
Dr. Walker
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