Posted by SLS on September 27, 2006, at 1:11:48
In reply to Re: genetics of schizophrenia, posted by alexandra_k on September 27, 2006, at 0:07:40
> If the schizophrenia gene (which isn't even close to being perfectly correlated with schizophrenia) decreased the individuals fitness then it would be hard to see why it is still in the population.
You know this isn't true. We still see Huntington's Chorea in the population.
One thing that we see emerge sociologically during evolution is care of the inferm. It is seen prehistorically as fossil remains have been discovered with clearly disabling skeletal injuries. I wonder to what degree schizophrenia and other mental illnesses were tolerated within the group? Did these people reach reproductive ages? Who cared for their offspring? Perhaps none of the above. Perhaps this is why we see major mental illnesses existing as multi-genetic. The only way these defective genes can exist in an intolerant population is if they do not express a dysfunctional phenotype without the simultaneous expression of other critical genes that themselves do not appear regularly and are not chromosomally linked (as a haplotype).
I think we do see that schizophrenia and bipolar disorder are multi-genetic disorders with several loci on different genes having been identified. I will, for the time being, exclude Major Depressive Disorder from the discussion, even though I believe it deserves a place as a biologically-driven mental illness with multi-genetic components.
> There could be something advantageous about 'the schizophrenia gene'
True.
- Scott
poster:SLS
thread:689461
URL: http://www.dr-bob.org/babble/20060919/msgs/689521.html