Predisposition to brain aneurysm found among Nunavik Inuit

Study highlights unique genetic makeup of the Northern Quebec population

The Kativik Municipal Housing Bureau is leading a wider, more co-ordinated effort to tackle bedbug infestations in its units, starting in Kuujjuaq this week and then in Hudson coast communities later this month. (File photo)

By Elaine Anselmi

A new study has found that an adaptive trait among Nunavik Inuit could explain the prevalence of brain aneurysms among the isolated population.

Published on Monday in the journal Proceedings of the National Academy of Sciences of the United States of America, the study by researchers at the Montreal Neurological Institute and Hospital, which is part of the McGill University Health Centre, sought to explain the high rates of certain health issues and a possible genetic link.

While figures for the rate of brain aneurysm among Nunavik Inuit, a relatively small population at about 13,000, are not tracked, the prevalence was observed through visits to the Montreal General Hospital, where Nunavik residents are flown for medical treatment.

With approval from the Nunavik Nutrition and Health Committee, researchers analyzed the DNA of 170 patients from 10 communities across Nunavik. The DNA samples were taken from blood drawn during visits to the hospital, with the express consent of the patients or their family members, going back 25 years.

Often, notes Dr. Patrick Dion, assistant professor of neurology and neurosurgery at McGill University, very little is known about remote populations who vary from those of European descent, so indicators of certain health problems are difficult to recognize in DNA.

The Nunavik Inuit, for example, have distinct genetic signatures linked to the way lipids—which include fats—are metabolized, which may be the result of the need to adapt to a high-fat diet and extreme cold, according to researchers. This study looked at the genetic architecture of Nunavik Inuit, compared to other DNA profiles, through the scope of natural selection.

“At the fundamental level,” says Dion, “it’s interesting to look at human evolution. Being isolated in regions where there are not so many fruits and vegetables, you adapt to your environment.”

That means your body finds a way to take from that environment what it needs to survive, and this function is imprinted on your DNA. But the researchers also considered how those adaptations could have negative effects if the environment that created those genetic variations changes.

One of the variants observed among the Nunavik Inuit is associated with the risk of intracranial aneurysm, where the wall of a cerebral artery weakens and balloons, potentially fatally rupturing. The study was limited to one-to-two per cent of the genome associated with aneurysms, and lead author Sirui Zhou suspects further investigation would find an even stronger correlation.

“The variants used to be beneficial because they are functioning in the lipid metabolism pathway, which are important for Inuit in their environment,” says Zhou. “But if this changes a bit, they are starting to have a higher risk because those variants are starting to have other effects.”

Some of the environmental change, Zhou says, could be the introduction of Western lifestyles.

“There are more carbohydrates in the food, they rely less on hunting and eating seal or fish every day,” she adds.

While this study looked specifically at brain aneurysms, cardiovascular disease and Type 2 diabetes are also prevalent among Nunavik Inuit. This study offers a baseline for understanding the unique genetic makeup of the population, which researchers compared to every known collection of DNA from populations, including Inuit of Alaska and Greenland, and Indigenous people of Russia, though Zhou says information about other Canadian Inuit is not known.

In general, genetic studies are lacking for remote Indigenous populations, says Zhou.

“It’s important to understand there is a genetic disposition to this kind of disease for the health care benefits for the community,” says Zhou, “and to understand a general way to provide health care.”

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(3) Comments:

  1. Posted by Not flawless on

    Wonderfully cautionary. Inuit have been photographed and studied for eons. We should be cautious about theses studies. Nonetheless let’s be open minded. Hopefully the study will include how inuit have adversely used alcohol overtime, and continue to spiral into intolerance and disease, mentally , socially, and physically. Surely DNA should be analyzed in this research with alcohol.

  2. Posted by Often wondered on

    The relationship between inuit and researchers can be greatly beneficial. I often wondered about the link between intracranial aneurysms suffered by central Nunavut inuit also. There are just so many cases for such a small population. Diet is so very important, evidence based science behind this statement. If inuit have distinct genetic signatures linked to the way lipids are metabolized, why isn’t there a partnership with inuit organizations and health departments that endeavor to educate the populous about their bodies and a creation of a food guide adapted to inuit? At the end of the day, inuit REQUIRE a high-fat diet.

    • Posted by Karl Popper on

      Your thinking is well ahead of the curve. But these are good points.

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