Thursday, 23 August 2012

One Step Closer to Unlocking the Secrets of Schizophrenia and Bipolar


Recent advances in technology have led to the uncovering of multiple genetic variations that cause two debilitating disorders, Schizophrenia and Bipolar together with a previously unknown relationship between the two.

Schizophrenia, sometimes referred to as a split personality disorder, is a mental illness that affects around 1% of the world’s population [1] and yet little is known about the causes [2]. Bipolar, a mood disorder, affects about the same percentage of the population and is characterized by severe mood swings [3]. Until recently, it was thought that these two disorders were just that, two different disorders.

Although little is known about the causes of these two disorders, it is apparent that they both run in families, indicating that these illnesses are inheritable.


When DNA is being replicated, mutations can arise and cause alteration in the structure of the chromosomes. As schizophrenia and bipolar were found to be inheritable, these mutations caused during errors in DNA replication would play a significant role in the appearance of these disorders.


Chromosomes can be mutated as a result of four different errors during this process. The four errors are deletion, duplication, inversion and translocation. Deletion is where a segment of the chromosome is removed, where as duplication is the opposite, a segment has been repeated [4].
Inversion occurs when the code is copied, but a section is reversed and in translocation, a segment of the chromosome is switched with a non-homologous chromosome (A chromosome that differs from the original).

The studies published in the 43rd volume of Nature Genetics focused on looking at the entire genome of subjects. A task that on paper does not seem like much but in reality is herculean, as a human genome is made up of roughly 3.4 billion base pairs [5]. Such a task was impossible until recently when technological advances in computer processing gave computers the ability to handle such a large amount of information.


The study on Schizophrenia was able to identify seven different genetic variations that were present in Schizophrenic patients, five of these seven being new [6]. This indicated that multiple different combinations of genetic mutation cause this illness, not just one isolated mutation.

Similarly the study on Bipolar aimed to isolate the genes directly related to the bipolar disorder as opposed to that of schizophrenia. The bipolar study used around 17,000 participants, with just over half of the individuals suffering from the disorder. This study was able to identify multiple pathways that led to the presence of Bipolar disorder in subjects.

Combined, the two studies uncovered an overlap in the genetic various leading two both debilitating disorders.
The main link was found within a gene, CACNA1C [7], which was first linked to Schizophrenia, but which after the recent study was also identified as taking a part in the manifestation of bipolar disorder.

By discovering that these two disorders are related, it is possible that in the future, with focussed research into that common area some form of treatment could be formulated to better manage both of these disorders.



Reference List:

[1] MedicineNet, 2012, Schizophrenia, viewed 15th March 2012,
<http://www.medicinenet.com/schizophrenia/article.htm>

[2] Frankenburg, F, 2012, Schizophrenia, viewed 15th March 2012,
<http://emedicine.medscape.com/article/288259-overview>

[3] MedinceNet, 2012, Bipolar Disorder (Mania), viewed 15th March 2012,
<http://www.medicinenet.com/bipolar_disorder/article.htm>

[4] Reece, J, Meyers, N, Urry, L, Cain, M, Wasserman, S, Minorsky, P, Jackson, R, Cooke, B 2011, Campbell Biology, 9th edn, Pearson Education, Australia

[5] Lanthier, C, 2008, How big is the human genome?, viewed 15th March 2012,
<http://nature.ca/genome/03/a/03a_11a_e.cfm>

[6] 2011, ‘Nature Genetics’, Genome-wide association study identifies five new schizophrenia loci, Vol.43,  no.10, pp. 969-976,
<http://www.nature.com/ng/journal/v43/n10/full/ng.940.html>

[7]
2011, ‘Nature Genetics’, Large-scale genome-wide association analysis of bipolar disorder identifies a new susceptibility locus near ODZ4, Vol.43,  no.10, pp. 977-983,
<http://www.nature.com/ng/journal/v43/n10/full/ng.943.html>

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