Mood-based disorders are one of the top-ten causes of disability worldwide. However the genes underpinning these disorders have proven to be remarkably elusive.
To try and identify such genes, researchers at Linköping University have used the process of domestication to help shed light on the problem. Domestication has led to a huge raft of changes, but one of the earliest to occur was a decrease in anxiety behaviour.
"Domestication therefore offers a unique opportunity to find the genes responsible for anxiety, by comparing domestic birds with their wild ancestors," says Dominic Wright, the lead researcher of the study now being published in the Genetics journal.
By crossing wild with domestic chickens for multiple generations in a genetic mapping experiment, then measuring a form of anxiety behaviour, gene regions affecting anxiety were identified.
Gene expression in a specific region of the brain, the hypothalamus, was then measured in over 120 individuals, and used to examine the genetic regions more closely, allowing the identification of ten genes affecting variation in anxiety behaviour in these birds.
By then using these genes as the basis for further investigation, additional datasets in humans and mice were then interrogated. Not only were significant associations for these genes found in mice also assayed in an open field arena, but links were also found for some of these genes in humans affected by schizophrenia and bipolar disorder.
"These results point to the same genes affecting anxiety in animals as diverse as chickens and humans. It also demonstrates that chickens may make an excellent model for the genetic basis of anxiety," says Dr. Wright.
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