Researchers Explain Why Humans Are Prone to Heart Attacks

Researchers from UC San Diego believe that humans are prone to heart attacks because of a gene that our ancestors lost millions of years ago.

According to a team at the University of California San Diego School of Medicine, our ancestors lost a gene millions of years ago. And this may be responsible for the increased risk of heart attacks or cardiovascular diseases in all humans as a species.

Atherosclerosis – also known as hardening of the arteries – occurs when the arteries become clogged with fatty deposit. When this happens to the arteries that carry blood to the heart muscle, it could lead to coronary artery diseases.

According to WebMD, coronary artery disease is the number one cause of death among Americans.

A decade ago, professor of pathology at UC San Diego School of Medicine Nissi Varkis and his colleagues made an extraordinary discovery. The researchers noted that coronary heart attack due to atherosclerosis doesn’t occur in other mammals.

These include chimpanzees exposed to human-like risk factors such as hypertension, high blood lipids, and physical inactivity.

In their new study, the researchers hypothesized that this is due to the absence of CMAH in humans. It’s the gene that produces a silica acid sugar molecule called Neu5Gc.

How the Absence of a Single Gene Increases Risk of Heart Attacks

For the study, the researchers modified mice to be deficient in Neu5Gc. Unlike the control mice who retained the CMAH, the modified mouse showed a significant increase in atherogenesis or formation of fatty plaques in arteries.

This led to the belief that a mutation occurred millions of years ago in our hominin ancestors, and this must have inactivated the CMAH gene. Furthermore, the researchers believe that the event is linked to the malaria parasite, which recognizes the silica acid sugar molecule.

In their findings, the team wrote that the removal of CMAH and Neu5Gc in the mice increased atherosclerosis severity by almost two-fold.

Co-author of the study and Distinguished Professor Of Medicine and Cellular And Molecular Medicine, Ajit Varki noted:

“The increased risk appears to be driven by multiple factors, including hyperactive white cells and a tendency to diabetes in the human-like mice. This may help explain why even vegetarian humans without any other obvious cardiovascular risk factors are still very prone to heart attacks and strokes, while other evolutionary relatives are not.”

Alongside the absence of CMAH gene, red meat intake also increases the risk factor.

How Red-Meat Increases the Risk of Atherosclerosis

Every time we consume red meat, we become repeatedly exposed to Neu5Gc. According to the researchers, this prompts an immune response and chronic inflammation called xenosialitis.

To test how red meat increases the risk of atherosclerosis, the researchers fed the mice modified to lack the CMAH gene a Neu5Gc-rich, high-fat diet. It resulted in a 2.4-fold increase in the risk of hardening of the arteries.

“The human evolutionary loss of CMAH likely contributes to a predisposition to atherosclerosis by both intrinsic and extrinsic (dietary) factors. And future studies could consider using this more human-like model,” the authors concluded.

The researchers linked the evolutionary loss of the CMAH gene with other significant changes in the human physiology. These include an enhanced ability to run long distances and reduced human fertility.