Posted by alexandra_k on September 27, 2006, at 0:07:40
In reply to Re: genetics of schizophrenia, posted by notfred on September 26, 2006, at 23:15:25
> Seems to me you cannot have hybrid vigor without
> some mistakes but they are self limiting via natural selection.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.
The study didn't make it very clear who the control group consisted in. Whether the control group consisted in people with other psychiatric dx or whether the control group were lacking a psychiatric dx altogether or both. That is important... With respect to seeing whether the gene does decrease individual fitness. Were the people in the control group who had the gene suffering from another mental disorder? How were they functioning in general? How many kids did they have?
There was a study done that showed that people with schizophrenia didn't have kids that much less than people without schizophrenia (I think males tended to have less but females tended to have more). That challenged the assumption that people with schizophrenia were less fit than people without. I don't know how much number of offspring is related to presence of the schizophrenia gene. I'm even reluctant to call it 'the schizophrenia gene' since it isn't necessary or sufficient for the development of the disorder.
One notion might be that presence of the gene predisposes... And then there is something environmental (like a virus in the third trimester) so that together those two conditions are sufficient for the development of schizophrenia. Still seems that the gene (and the virus) isn't necessary, however...
There could be something advantageous about 'the schizophrenia gene' so that it increases individual fitness (so long as the virus, lets say, doesn't come along). One idea that comes up is creativity. I guess if you had an operational definition of creativity you could do a survey and figure whether that were true or not.
Another theory is that it could be similar to sickle cell anemia. With sickle cell anemia you want one... Can't remember what it is called... You want Bb to be resistent to malaria. If you are bb then you aren't resistent. If you are BB then you have sickle cell anemia. B (the sickle cell anemia gene or whatever) is maintained in the population because it benefits people in the form of providing resistence against maleria (that is what has maintained the presence of the gene in the population). But the nasty offshoot of that is the possiblity of BB or sickle cell anemia. Whatever genes are involved in schizophrenia could work like that too...
I guess my main worry is that we don't know enough about what the genes do to say whether knocking them out / turning them off (in the form of pre-embryos) would be helpful or harmful to the population as a whole. We don't even know enough to know whether it would be helpful or harmful to the individuals...
Stuffed if I know.
But given the gene (and the virus) don't seem to be necessary or sufficient for the development of the disorder maybe there are different kinds of schizophrenia or maybe we just need more genetic research or maybe... The environment (aka sociological conditions) play a bigger role than is commonly supposed...
Does exposure to a virus count as environmental?
How about adequate nutrition?Stuffed if I know
poster:alexandra_k
thread:689461
URL: http://www.dr-bob.org/babble/20060919/msgs/689506.html