Genetic Predisposition
Posted: Sun Sep 16, 2007 4:48 pm
I know I brought this subject up about a year ago but there is no doubt that we have all learned a lot in the time since.
The assumption of genetic predisposition is one of the earliest and longest held assumptions in the history of modern MS research.
The assumption of genetic predisposition was/is based on incidence data showing that MS predominantly, at that time almost exclusively, affected light skinned caucasians, seemingly regardless of location (either side of the equator, in the midst of populations with low MS incidence, etc..)
This led to, what seemed, the logical assumption that darker skinned people had an immunity to MS or that lighter skinned people have a genetic predisposition.
In the years since, the incidence data has changed drastically and a multitude of studies have shown that darker skinned people have no immunity to MS and therefore Caucasians have no genetic predisposition. Despite it seeming otherwise earlier, the situation is as it always was and MS incidence never has been one of genetic predisposition. Human genetics aren't capable of changing that fast.
Because of "familial clustering" I am not so foolish as to think that genetics aren't involved in MS incidence, but it now seems obvious that MS incidence is owed to "environmental predisposition" (as the only alternative to "genetic predisposition") and genetic factors, and possibly other environmental factors are secondary "triggers" (only after environmental predisposition could these triggers enable the MS process to begin).
Considering the situation, I don't see how anyone could make a logical argument for genetic predisposition. If you think you can, I'd love to hear it.
Bob
The assumption of genetic predisposition is one of the earliest and longest held assumptions in the history of modern MS research.
The assumption of genetic predisposition was/is based on incidence data showing that MS predominantly, at that time almost exclusively, affected light skinned caucasians, seemingly regardless of location (either side of the equator, in the midst of populations with low MS incidence, etc..)
This led to, what seemed, the logical assumption that darker skinned people had an immunity to MS or that lighter skinned people have a genetic predisposition.
In the years since, the incidence data has changed drastically and a multitude of studies have shown that darker skinned people have no immunity to MS and therefore Caucasians have no genetic predisposition. Despite it seeming otherwise earlier, the situation is as it always was and MS incidence never has been one of genetic predisposition. Human genetics aren't capable of changing that fast.
Because of "familial clustering" I am not so foolish as to think that genetics aren't involved in MS incidence, but it now seems obvious that MS incidence is owed to "environmental predisposition" (as the only alternative to "genetic predisposition") and genetic factors, and possibly other environmental factors are secondary "triggers" (only after environmental predisposition could these triggers enable the MS process to begin).
Considering the situation, I don't see how anyone could make a logical argument for genetic predisposition. If you think you can, I'd love to hear it.
Bob