Siblings, offspring, and parents have approximately 50 percent similarities in their genetic material. This sharing of genetic material allows for traits and risk factors to collect within a family. Similarly, individuals are more likely to share similar genetic variation within their racial/ethnic demographic.
Family history of cardiovascular (heart) disease is potentially one of these shared familial traits. It is not known if family history of heart disease is attributed to shared behaviors (smoking, alcohol use, diet, etc.) or to the accumulation of other risk factors (high blood pressure, diabetes, obesity, etc.) that may have both an environmental and genetic cause.
Genetic research on heart disease is extraordinarily complex and still relatively new; however, there is some data that may be able to help individuals with a family history of heart disease better understand their risk.
Family history of premature (< 50 years old) heart attacks is a good indicator of risk for potential heart disease. It was found that paternal history of a premature heart attack doubles the risk of a heart attack for their son(s) and increased the risk for their daughter(s) by approximately 70%.
A history of heart attack in both parents, especially where at least one is premature, makes their children 3 – 6.5 times more likely to have a heart attack, Table 1. A sibling with heart diseases increases the risk of heart disease by approximately 50% for both their brother(s) and sister(s).
These shared family histories are likely caused, in part, by genetic similarities.
Table 1. Combinations of parental heart attack history (Chow et al., 2011)
The full genetic basis for heart disease has not yet been determined, and currently genetic risk predictions do not add much over family history risk predictions. However, there are a few genetic markers that show potential indication of risk for heart disease.
In addition, studies have shown that risk factors for heart disease such as high blood pressure, obesity, high cholesterol, diabetes, and poor kidney function are moderately heritable. This means that there is a chance that any or all these risk factors could be passed from parents to children.
The most consistently replicated genetic marker for heart disease is located on the genome at position 9p21.3 (Manjula 2020).
This genetic marker is most commonly found in European-derived populations. Approximately 50 percent of this population has one occurrence of this marker, 23% has two occurrences of this marker, and remaining 27% has none.
For a 65-year-old man, that has no other traditional risk factors for heart disease and has no occurrences of this genetic marker, would have a 9.2% chance of developing heart disease over the next 10 years. But the same individual with 2 occurrences of this genetic marker would have a 13.2% of developing heart disease over the next 10 years.
For a 40-year-old woman, that has no other traditional risk factors for heart disease and has no occurrences of this genetic marker, would have a 1.7% chance of developing heart disease over the next 10 years. But the same individual with 2 occurrences of this genetic marker would have a 2.4% of developing heart disease over the next 10 years.
This genetic variation can not only increase the risk of heart disease, but also has been linked to increased risk of stroke, heart failure, aneurysms, and sudden death. While this genetic variation has been seen to increase risk, the biological link between this marker and these various disease outcomes is still unknown.
Several factors play roles in heart health, but family history seems to be a strong indicator of future heart attacks. Data from several studies indicate that people carrying certain genes, and with known history of cardiac issues in family at relatively young age, are at higher risk. They may benefit from genetic testing while careful monitoring their lifestyle and environmental factors.
Chow et. al. Parental history and myocardial risk across the world: The INTERHEART study. Journal of the American College of Cardiology, 57(5), 619 (2011).
Roger et. al. Heart disease and stroke statistics—2012 update: A report from the American Heart Association. Circulation, 125(1), e2 (2012).
Manjula et al. The SNP rs7865618 of 9p21.3 locus emerges as the most promising marker of coronary artery disease in the southern Indian population. Sci Rep 10, 21511 (2020).