In our human-centric way, one of the biggest questions in modern genetics is what makes us act the way we do? Understanding the genetic basis of human behaviour is a major goal for many scientists, but an important (and difficult) first step is the successful mapping of the genes underlying quantitative trait loci (QTLs) known to contribute to complex phenotypes such as neuroticism. This trait is of particular interest due to its association with many psychiatric disorders including depression and anxiety. A QTL shown to influence neuroticism has been located on human chromosome 1, but just how do we set about finding the genes responsible for regulating this trait?
That’s where the more genetically tractable model organisms come in. By successfully studying QTLs for the quantitative trait, "emotionality" (determined by a quantitative “EMO” score), and subsequently the putative genes, in mice, the human genome can potentially be analysed to see if any of the candidate mouse genes correlate with any of similar function and location in humans.
Validating this comparison, studies show that the mouse EMO QTL is one of the few behavioural QTLs which correlate to human QTL. Further evidence suggesting the comparison between mice and humans is fair includes functional and anatomical similarities between the emotion centres of the brain, and some identical pharmacological treatments for anxiety.
So, by studying mice before humans, we may be able to gain valuable insight into the genetic basis of traits such as neuroticism and emotionality.
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References:
1. Willis-Owen, S.A.G. & Flint, J. (2007), Identifying the genetic determinants of emotionality in humans: insights from rodents. Neuroscience and Behavioural Reviews, 31, 115-124.
2. Fullerton, J., Cubin, M., Tiwari, H., Wang, C., Bomhra, A., Davidson, S., Miller, S., Fairburn, C., Goodwin, G., Neale, M.C., Fiddy, S., Mott, R., Allison, D.B. & Flint, J. (2003), Linkage analysis of extremely discordant and concordant sibling pairs identifies quantitative-trait loci that influence variation in the human personality trait neuroticism. Am. J. Hum. Genet., 72, 879-890.
3. Mackay, T.F.C. (2004), Complementing complexity. Nature Genetics, 36(11), 1145-1147.
