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Scientists in Genome Atlantic project discover gene linked to brain evolution
HALIFAX - Researchers have found a gene that appears to be linked to brain size, a key differentiator between humans and most other mammals.
“When you go back to the basic questions of what makes us human, this is a very interesting discovery,” says Dr. Mark Samuels, Adjunct Professor in Pathology at Dalhousie University and Associate Professor in Medicine at the University of Montreal. Brain size, as well as speech, opposable thumbs and walking upright are generally regarded as some of the major evolutionary steps that separated humans from apes.
The discovery, published July 1st in the online version of the American Journal of Human Genetics, was made by Dr. Mark Samuels and a team of researchers from Dalhousie University and the IWK Health Sciences Centre in Nova Scotia, the Centre de Recherche du CHU Ste-Justine and the University of Montreal in Quebec, and the German Cancer Research Center in Heidelberg, Germany.
The team made the discovery while looking for the cause of a rare genetic disorder known as primary microcephaly, which results in a smaller than average brain and may be accompanied by a range of developmental delays. After mapping a chromosomal region in the genomes of Maritime Canadian microcephaly patients, they found two different mutations in the gene, CEP152, which had not yet been documented for any human genetic disease.
CEP152 normally plays a role in cell division, which could explain the reduced brain size in patients carrying defective copies of the gene. When the team looked at the equivalent of this gene in other species, they found that it had changed a number of times over a relatively short period of time, evolutionarily speaking. In particular, the number of changes between other animals and humans was higher than would be expected by chance. This type of increased gene change is referred to as positive selection, and is usually interpreted as evidence for adaptive evolution in response to new demands on an organism. In this case, the speculation is that our predecessors needed to develop larger brains to allow more complex thought and development for survival.
“Ten years later, projects like ours are still adding valuable insight into the human genome,” says Dr. Guernsey. “Every little piece of this giant puzzle gives us a better understanding of the big picture of life, including how we became what we are.”
At the same time, this team is also having more practical impact; identifying the genes that cause childhood genetic diseases, like the microcephaly search that led to this discovery.
“Discoveries in childhood genetic diseases can lead to earlier diagnosis, particularly in pediatric medicine,” says Dr. Samuels. “And earlier diagnosis can lead to better, more efficient patient care.”
This most recent discovery is part of the Atlantic Medical Genetics and Genomics Initiative, a Genome Atlantic-led project that aims to find the genetic cause of nearly 30 monogenic diseases in Atlantic Canada. The Maritime component is funded in part by Genome Canada/Genome Atlantic, Capital Health, IWK Health Centre, Dalhousie University, Nova Scotia Research and Innovation Trust, Dalhousie Medical Research Foundation, Nova Scotia Health Research Foundation and others as listed at www.amggi.ca
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About the Atlantic Medical Genetics and Genomics Initiative
The Atlantic Medical Genetics and Genomics Initiative is a $9.2M, multi-partner, multi-institution research project designed to find the genetic cause of nearly 30 monogenic diseases in Atlantic Canada. Leveraging the expertise of a wide range of medical and research professionals from medicine to genetics and genomics to ethics, the project aims to integrate gene research into clinical practice for advanced knowledge and improved health care.
The project is funded in part by the Government of Canada through Genome Canada/Genome Atlantic, and by Capital Health, IWK Health Centre, Dalhousie University, Nova Scotia Research and Innovation Trust, Dalhousie Medical Research Foundation, Nova Scotia Health Research Foundation, ACOA, Janeway Children’s Hospital Foundation, Memorial University, Newfoundland and Labrador Centre for Applied Health Research, Newfoundland and Labrador Department of Health and Community Services and others as listed at www.amggi.ca
About Genome Atlantic
Genome Atlantic is a not-for-profit organization that was formed in 2000 with a mission to develop and lead a program of genomics research that delivers tangible economic, social and environmental benefits to Atlantic Canada.
In its first ten years, Genome Atlantic has partnered with government, academic, industry and research institutions to enable ten projects totaling $68 million, ranging from agriculture and forestry, to aquaculture and human health. It is one of six genome centres across the country, under the umbrella of Genome Canada.
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Sue Coueslan
Director of Communications and Government Relations, Genome Atlantic
902.222.3178
