Wednesday, April 30, 2014
Stats and Reflection
Our BOINC GPU grid computed 131 units for the Barcelona Biomedical Research Park - Molecular Simulation of Proteins. This means that through the duration of this project, our computer looked at 131 units of proteins using its computational power. 19,111 tasks are currently in progress on this grid, and we have contributed to one of them. This company currently has 45,000 computers computing for this research. It really shows how much power is needed to do these simulations for their research. We find this incredible because we feel like we helped make a difference without really doing direct work. It's crazy how technology is advanced enough that we were able to contribute to research. It's amazing how anyone in the world with an electronic device with computational power can help contribute to any research that they are interested in by simply downloading a program. This project really helped bridge the gap between the concepts we were learning in class to real world research and issues. We were able to make new connections between a commonly known disease to evolutionary ideas we learned. We would have never taken this approach in looking at Schizophrenia. If it weren't for this project, we wouldn't know about the power of grid mapping and using blogs.
Wednesday, April 2, 2014
Schizophrenia Q&A
Questions – Schizophrenia
These questions address the Schizophrenia Bulletin article entitled “Schizophrenia, Psychiatric
Genetics, and Darwinian Psychiatry: An Evolutionary Framework” by Peralson and
Folley, 2008.
- Is
schizophrenia a qualitative or quantitative trait? What is the estimated heritability of
this phenotype?
This is most likely a multi-gene
trait with common alleles that are risks to causing this disease. By themselves, those genes would not cause
the disease, but when they all come together the disease is manifested
(polygenic disease). All genes are
needed for the disorder to be present.
This makes it a quantitative trait.
No specific genes are linked to Schizophrenia, but a number of genes
contribute to causing the disorder. They
increase the probability of the disease manifesting in a person.
In
concordance studies with twins, in identical twins, they are forty to sixty
percent likely to get the disease, as opposed to fraternal twins that are ten
to twenty percent likely to get the disease.
This indicates that genetics has a lot to do with the cause of the
disease, but environment still plays a point (“The Heritability of
Schizophrenia”). Disequilibrium studies
have also been performed. In these
studies, large families affected by the disease are studied and their
chromosomes are compared to families who are not affected. From these studies, it has been shown that no
specific chromosomal locations have been found that specifically cause the
disease. A variety of loci contribute to
causing the disease. When assessing
families with Schizophrenia, the family genes are combined for assessment
because of the smaller family size. This
can cause issues to identifying specific genes that cause the disorder because
some families may have different genes specifically causing the disease than
another family (“Schizophrenia and Genetics”).
- What
kind of inheritance explains the observed patterns seen in schizophrenia?
It is the unfavorable combination
of specific genes that contribute to neuron and brain development. These changes in the genes are due to copy
number variance and single nucleotide polymorphisms within the normal
range (refer back to question 1 for more specifics).
- Why
do schizophrenia risk genes persist in evolution?
The genes themselves are not
selected against when inherited singly.
They are “below the radar” of selection.
Some inherited individually have a compensatory advantage or are neutral,
keeping them in the population. These
genes are only selected against when the right combination is inherited and the
disease occurs.
- What
are the possible heterozygote advantages associated with schizophrenia? Do you agree?
These alleles alone can be
associated with normal or increased fertility, making them advantageous. Another advantage associated with Schizophrenia
for the genes would be in an ancestral environment. An example of how these genes came to be
would be through “broken genes”. For
example, some genes provided protective advantage with salt retention when salt
was not readily available in the environment.
Overtime, keeping this trait when sodium is now plentiful contributes to
the elevated levels of hypertension seen in society today. There is a similar idea with diabetes. In the ancestral environment, these genes
expressed hormones that caused insulin resistance that helped with more
effective fat storage, helping with limited availability of food. Now this trait is disadvantageous and causes
elevated levels of obesity in people with this disease because of unnecessary
fat storage. These genes are associated
with causing diabetes. There might have
been adaptations that Schizophrenia susceptibility genes caused, but they have
yet to be identified. Schizophrenia
might have been advantageous in causing paranoia in ancestral environments,
helping protect the person from predators or other possible dangers. We agree with these ideas the paper
presents. As the environment changed
over time, the advantages the genes offered also changed. Because of modern medicine, these traits will
be retained in the population, as these issues most likely can be treated. Also, carriers will continue to contribute
these traits to the next generation.
- If
heterosis is acting on the schizophrenia alleles, what might you expect
will happen to these alleles over the long term ? (Think fitness tables...)
If heterosis is acting on the
schizophrenia alleles, you would expect that over a long period of time the
heterozygote genotype will become fixed in the population with the homozygote
dominate and homozygote recessive genotypes going to an equilibrium based on
the frequency they are at during the time heterosis is selected for. This means that the schizophrenia alleles
will always be in the population. There
will always be a small population of people who are affected by schizophrenia
because currently only one percent of people are affected.
- This
paper, and much of evolutionary psychology, is panselectionist or
ultradarwinist. What does that
mean? What other mechanisms of
evolution might be at play here?
A panselectionism is the belief
that the only mechanism of evolution was natural selection and that all genes
are inherited (“Neo-Darwinism”). An
ultra-darwinist is a person who believes in Darwin’s idea of natural selection,
but thinks that it is the only mechanism of evolution (Cain 220). This paper emphasizes these ideas greatly,
putting great consideration on natural selection in the evolution of the
schizophrenia genes. The paper briefly
mentions that sexual selection may have caused schizophrenia to appear in the
population. Exaptation is also
mentioned, as some of these genes may have started being used for other
functions like speech and art. Other
mechanisms of evolution that should be considered when analyzing these traits
should be mutations, genetic drift, and gene flow. There might have been disadvantageous
mutations that caused these alleles to become present in the population. Founder affect might have occurred, bringing
together a population with these alleles that would increase the frequency of
inheriting schizophrenia susceptibility genes.
Gene flow might have then integrated these alleles into larger
populations over time.
If you want to read more, check out this link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2632450/
Works Cited
Cain, Clifford Chalmers. "Darwin's Pious Idea: Why
The Ultra-Darwinists And Creationists Both Get It Wrong - By Conor
Cunningham." Reviews In Religion & Theology 19.2 (2012): 220-221.
Academic Search Complete. Web. 2 Apr. 2014.
"The Heritability of Schizophrenia." Biological
Basis of Mental Health. Open Educational Resources, n.d. Web. 2 Apr. 2014.
"Neo-Darwinism." Princeton University.
N.p., n.d. Web. 02 Apr. 2014. <http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Neo-Darwinism.html>.
"Schizophrenia and Genetics: Research Update | Psych
Central." Psych Central.com. N.p., n.d. Web. 02 Apr. 2014.
<http://psychcentral.com/lib/schizophrenia-and-genetics-research-update/0008736>.
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