People of European and African Descent Share Similar Genetic Predisposition Towards Schizohrenia
by SchwerdtfegerK on May 10, 2017 - 12:35am
Schizophrenia can be a tricky illness to define; not all symptoms are common from individual to individual, and even symptoms like hallucinations and delusions are not universal symptoms. The one correlation that can be found is the presence of Thought Disorder: the loss of logical thought processes that either allow the affected individual to make sense of their own thoughts, or keep their thoughts in a logical pattern and reason away ideas we could easily deem absurd.
Medical criteria aside, it is even more difficult to pinpoint any specific cause for schizophrenia. What genetic correlations have been found are scattered across different chromosomes and would otherwise seem unrelated to one another. Furthermore, one can have a predisposition to the illness but not express it until an environmental force brings it to the forefront.
The American Journal of Human Genetics published a study called “Additive Genetic Variation in Schizophrenia Risk Is Shared by Populations of African and European Descent” back in 2013. In said study, a team of scientists (Teresa R de Candia, et. al.) took on the task of assessing genetic similarities between schizophrenics of differing populations. While studies in genetic factors for developing schizophrenia are nothing new, this study brought forth an interesting assessment. The team collected DNA samples of affected individuals (a total of 2,142 being of African descent, and a total of 4,990 individuals of European descent) and searched for common single-nucleotide polymorphisms (SNPs).
Previous studies had already established a correlation between certain SNPs and schizophrenia affliction, but had only been tested for among people of European descent. The correlation between the observed SNPs and European populations is stated in the aforementioned study to have a correlation rate of 0.665, but in said study, they al
so established a correlation rate of 0.61 for the same SNPs among African populations.
Though the correlation rate is slightly lower, it is still similar enough to imply a common set of genetic traits between distant populations. The interesting implication is that schizophrenia may have an origin in humans that predates out-of-Africa migrations, and that schizophrenia may be a complex multifactorial allele that goes back very far in our evolution.
Personally, I suppose I could call mental disorders an interest of mine, insomuch as I am interested in their implications on the workings of the mind, as well as its limits. The fact that something we understand to be nebulous and undefinable as our perception of the world can be affected by external stimuli, or even just by our genes alone.
I feel I have an odd personal connection with schizophrenia, as well. My uncle developed it in his early adulthood, and it was intense to see someone who once acted normal become something most would never think of as ever having been close to a normal human being. I suppose what I am drawn to is a better understanding of the illness; where it comes from, how it can be counteracted, or how it may even be prevented entirely.
This study, in particular, caught my eye because I find it an interesting idea that schizophrenia could have been a part of our prehistoric evolutionary history and how earlier cultures may have perceived this deviation from typical human cognition. On a more basic scientific level, it intrigues me that the genetic potential for schizophrenia may be rooted enough in our genetic code that unrelated populations could possess almost the same alleles for the condition. I am also intrigued by a possibility that schizophrenia may not just be unique to Homo sapiens, but may have existed in other species of humans that are now long-extinct or have originated in an earlier ancestor of ours.