Monday, 2 April 2012

Genetic Factors affecting outcome following Traumatic Brain Injury


Genetic Factors affecting outcome following Traumatic Brain Injury
Research by Ramon Diaz-Arrastia and Victoria Baxter at the University of Texas Southwestern Medical Center in Dallas, provides an insight into how genetic factors play a role in the outcome of traumatic brain injury.  This 2006 research draws on the 1999 work of Friedman, Froom and Sazbon that identified the association between apolipoprotein E4 allele (APOE ε4) and poor outcomes following traumatic brain injury and provides suggestions for future directions in research related to how genetic factors may contribute to explaining the pathophysiology of traumatic brain injury. 
Firstly, I need to explain what traumatic brain injury means and provide some data regarding its occurrence in Australia.  According to information provided by Brain Injury Australia, traumatic brain injury (TBI) is the second largest cause of acquired brain injury in Australia (stroke is the most common cause of acquired brain injury) with over 22 000 people hospitalised annually for the condition.  The Association also reports that two fifths of the injuries resulted from falls, one third were caused by motor vehicle accidents and one sixth were the result of assault.  The impact of TBI varies on an individual basis and can include issues with cognition, psychological problems, communication difficulties and physical and sensory problems.  

The first significant theme identified in Diaz-Arrastia and Baxter’s research is that there are three key pieces of evidence that link functional outcomes from TBI to genetic factors.  The first factor is the already mentioned link between APOE ε4 and the increased possibility of a poor neurological outcome following TBI.  The second factor relates to research on different strains of mice which showed significantly different impacts from neurodegenerative injuries.  Finally, research investigating the relationship between Interleukin-1 (both IL-1α and IL-1β) and TBI is analysed to identify that these cytokines may also be indicators of poor outcomes.  The authors, however, emphasise that while these links have been established, genetics indicators do not predestine a person with TBI to a certain outcome but rather are polymorphic; that is, they are common variants that result in increased risk of a poor outcome.
 

In regard to conclusions and future research areas, the authors make two main points.  Firstly, in contrast to single gene disorders such as cystic fibrosis and haemophilia, genetic research regarding TBI has the potential to provide more accurate prognosis information and identify those at higher risk of poor outcomes, rather than providing a definitive diagnosis.  Secondly, further research is required to determine if particular polymorphisms are associated with poor outcomes following specific types of traumatic brain injuries.  The authors also suggest that the genes which impact in the early phase of treatment when swelling and inflammation are prevalent may be different from the genes which are relevant in the rehabilitation phase of TBI.
Personally, I found this research to be of interest as I had not considered that genetic research could be relevant to illnesses, such as traumatic brain injuries, which are caused by environment factors.  I believe that the insight provided by this research into the role of genetics in prognosis and the potential for genetics to play a role in treatment and rehabilitation is significant.

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