RESEARCHERS (L TO R) MENA ABDELSAYED, COLIN PETERS AND PETER RUBEN.

New research at Simon Fraser University is shedding light on how sleep and exercise may be dangerous for those with a mutation in a gene that is important for proper heart function.

Peter Ruben, a professor in SFU’s Molecular Cardiac Physiology lab explains that, when sleeping and exercising, our bodies undergo changes. These include fluctuations in body temperature, the level of acid in our blood, and intracellular calcium levels.

Ruben says, “In people who have a rare mutation in their DNA, these changes can lead to cardiac arrhythmias and sudden cardiac death.”

The mutation means a protein is made incorrectly. The protein is vital for proper heart function and is partly responsible for the electrical signal passing through the heart in an organized fashion.

“When the protein is made incorrectly, the electrical signal can become disorganized, leading to parts of the heart contracting before they should,” says Ruben. “When that happens, the heart no longer acts like an efficient pump.”

Colin Peters, a PhD candidate in Ruben’s lab, studied how the mutation itself disrupts the electrical signal as it passes through the heart. Peters says that properly functioning protein moves sodium into the cells of the heart, an important step in coordinating cardiac contraction.

“We found that the mutation changes how quickly the sodium movement stops, which can then lead to arrhythmia and cardiac arrest,” says Peters.

Knowing how calcium levels, blood acidity, and body temperature affect those with the mutation will help cardiologists and patients better understand why some seemingly healthy people can be at risk for sudden cardiac death during exercise and during sleep.

Situations can include the athlete who keels over in the middle of a game, and infants who succumb to Sudden Infant Death Syndrome (SIDS).

“If someone thinks they are at risk because of a family history of sudden unexpected death or unexplained fainting, they should consult their family doctors,” says Ruben.

The research was recently published in PLOS One and the Journal of Physiology.