Genetic advantage now puts Inuit at risk of SIDS, research confirms

This graph shows the distribution of the CPT1a enzyme.

In the past, it was an advantage for Inuit to be able to thrive on fat from sea mammals and other wildlife for energy, but these days, that same genetic advantage may prove life-threatening for their babies.

Medical researchers believe a variant of the CPT1a enzyme offered an advantage to people who migrated to North America from Siberia 3,000 to 5,000 years ago.

Their high-fat diet would have favoured a different kind of metabolism, one that used fats, rather than sugars, for energy.

“With agriculture being unsustainable in this part of the world as a result of its extremely cold environment, these coastal populations mostly fed on marine mammals for a high-fat diet,” says a recently-published paper in the American Journal of Human Genetics.

But the authors of this paper now say CPT1a “joins the short list of known human variants where ill health in present-day populations is a likely consequence of the same variant’s being selectively advantageous in the past.”

That’s because this form of CPT1a, also found from Alaska to Greenland, can lead to severe low-blood-sugar complications.

These may become worse during illness — and the effects can range from seizures to sudden unexpected death.

The Arctic variant of CPT1a has been associated with infant mortality in all populations where it’s found, according to information presented at the International Conference on Circumpolar Health in Oulu, Finland earlier this year.

As well, babies with this CPT1a variant enzyme appear to be at risk of lung and ear infections, although with age, this apparent susceptibility to dangerous low-sugar events appears to decrease.

But the CPT1a variant may be associated with the overall high mortality of infants from one month to one year old in Nunavut, which is nine times higher in the territory than nationally in Canada.

However, a newborn screening program or easy-to-access information for parents or health staff is not yet available in Nunavut to help prevent life-threatening health reactions that could affect the majority of babies born in the territory.

This information is already available in British Columbia to health workers and First Nations families whose babies share the same enzyme variant CPT1a. And in Alaska, CTP1a screening has taken place since 2003.

There’s even a YouTube video with information about CPT1a and how to keep babies with the variant healthy.

Earlier research has shown that seven in 10 infants in the Kitikmeot and Kivalliq regions of Nunavut and about half of the babies from the Baffin region are born with this variant of the CPT1a enzyme.

This same enzyme variant, found in the majority of Nunavut babies, can lead them in some cases, about one in 300, to develop severe low blood-sugar, or hypoglycaemia, when they are sick or not eating properly.

Dr. Laura Arbour, a medical geneticist at the University of Victoria and expert on the CPT1a variant, told Nunatsiaq News in Oulu that she received money from the Canadian Institutes of Health four years ago to pursue research on CPT1a in Nunavut, but this research has not yet taken place.

A 2012 paper published in BMC Pediatrics, with input from Arbour, the Government of Nunavut and Nunavut Tunngavik Inc., on the “Causes and risk factors for infant mortality in Nunavut, Canada 1999—2011,” suggested the association between CPT1a and unexpected infant death could represent “a complex interaction of the variant with environmental risk factors including sleep position, bed-sharing, prenatal and postnatal tobacco smoke exposure and food security.”

That paper was openly followed two years later by an advisory suggesting Nunavut parents make sure their babies sleep on their backs.

Medical professionals in Oulu said what to do about CPT1a in Nunavut remains a highly “political issue,” due to the ongoing public health debate around what information to give people about the health risks they face, even when some of these are preventable.