Study Reveals Blood Type A is More at Risk of Having a Stroke at a Young Age

JAKARTA - A study reveals interesting findings about the relationship between blood type and stroke risk at a young age. Research results show that people with blood type A, especially certain subtypes, have a higher risk of having a stroke before the age of 60.

The findings, published in a 2022 study, add to the understanding of how unchangeable biological factors, such as blood type, can affect a person's health.

"This important and quite surprising study adds to our knowledge of modifiable risk factors for stroke, including a person's blood type," said Mark Gladwin, a doctor and researcher from the University of Maryland, when the study was released, as quoted from the Science Alert page.

Until now, blood types are known as A, B, AB, and O. This classification is based on chemical markers or antigens found on the surface of red blood cells. However, within each blood group there are still small variations due to certain gene mutations.

In this study, scientists analyzed data from 48 genetic studies involving about 17 thousand stroke patients and almost 600 thousand control people who did not have a stroke. All participants were aged between 18 and 59 years.

The results of the analysis showed a clear relationship between the genes that determine the A1 blood subgroup and the risk of stroke occurring earlier.

"The number of cases of stroke in young people continues to increase," said the lead author of the study and vascular neurologist, Steven Kittner, from the University of Maryland.

"This group has a higher risk of death from stroke, and those who survive can live for decades with disabilities. Unfortunately, research on the causes of early stroke is still very limited," he continued.

Large-scale genetic searches have found two gene locations strongly associated with the risk of stroke at a young age. One of them is in an area of the genome that regulates blood type.

Further analysis showed that people with blood group A gene variants had a 16 percent higher risk of stroke before the age of 60 than people with other blood groups. Conversely, those who have the O1 blood group gene actually have a 12 percent lower risk.

However, the researchers emphasized that the increased risk in blood group A owners is small. Therefore, no special vigilance or additional examination is required based solely on blood type.

"We still don't know for sure why blood type A can increase the risk of stroke," said Kittner.

"However, it is most likely related to blood clotting factors, such as platelets, cells lining blood vessels, and other proteins in the blood that play a role in clot formation," he added.

In order not to cause excessive concern, the results of this study need to be viewed in a broader context. In the United States, nearly 800 thousand people have a stroke every year. About three-quarters of cases occur in those aged 65 years and over, with the risk doubling every decade after the age of 55.

In addition, the majority of study participants came from North America, Europe, Japan, Pakistan, and Australia. Non-European participants only account for about 35 percent of the total sample. Further research with a more diverse population is still needed to clarify the meaning of these findings.

"We clearly need more follow-up studies to understand the mechanisms of this increased stroke risk," Kittner added.

Another important finding was obtained when researchers compared patients who had a stroke before the age of 60 with those who had a stroke after the age of 60. For this analysis, data on about 9,300 stroke patients over the age of 60 and about 25 thousand peer comparison people who did not have a stroke were used.

The results showed that the increased risk of stroke in blood group A was no longer significant in the elderly stroke group. This indicates that the mechanism of stroke in young age is likely to be different from stroke that occurs in old age.

According to the researchers, strokes in younger people tend not to be caused by a buildup of fat in the blood vessels (atherosclerosis), but rather are more related to blood clotting disorders.

The study also found people with blood type B had an approximately 11 percent higher risk of stroke than those who had not had a stroke, regardless of age.

Previous research has shown the part of the genome that regulates blood types, known as the 'ABO locus', is also linked to coronary artery calcification which can hamper blood flow and increase the risk of heart attacks.

In addition, the gene sequence for blood types A and B is also associated with a slightly higher risk of blood clots in veins.