The Genetics Behind Fainting

  http://www.sciencedaily.com/releases/2012/08/120806161727.htm

   The act of fainting (vasovagal syncope) has always seemed to me to be the human body's reaction to particular physiological or environmental situations. However, according to recent discoveries by the University of Melbourne (Victoria, Australia) in Neurology®, fainting is not necessarily just due to external triggers. Apparently people can have a strong predisposition to having problems with fainting based on genetics. This brings up the debate of nature vs nurture-- for instance, did a child faint due to a trigger like dehydration or does it just run in their blood? The author of this study, Samuel F. Berkovic, studied twins to determine if fainting can be genetic.

   In this study of 51 same-sex twins (at least one had fainted before), 57% had a history of fainting in the family and those that were identical twins were shown to be twice as likely to have fainting problems as opposed to fraternal twins. This is because identical twins come from one fertilized egg (not two like fraternal) so therefore they inherit the same genes. And the risk of fainting with and without environmental triggers was higher for identical twins than fraternal twins. The article summed up saying that although fainting has been proven to be genetic, it is most likely coded by multiple genes and therefore doesn't have a strong genetic component in non-twin relatives. It also recognizes that fainting is not just genetic as it is often brought about by multiple environmental factors.

  It was interesting for me to see in this article how what we've been learning about the beginning of life and DNA replication takes effect. That identical twins might share this fainting characteristic because they came from the same fertilized egg because of the DNA replication producing the same genes for each child. It also brought me a new understanding of what it means when people say things like, "heart problems run in the family" that it is not just physical characteristics, diseases, and disorders that are determined by genetics but possibly all kinds of physiological problems.

  Admittedly, this study does not seem very revolutionary or dramatic. The science behind it was not particularly technical but it brought about new information nonetheless. Although it may not have drastic effects on the science community, it is still a piece of knowledge scientists have in their back pocket for the future and for further studies. For instance, if a doctor had a patient with frequent fainting they may be able to determine if it is because of genetics or environmental factors and if a twin might suffer the same problems too.