Studies estimate that one in every three adults around the world has high blood pressure (BP), also known as hypertension. According to the World Health Organization (WHO) high blood pressure is responsible for 7.6 million deaths every year, or around 13 percent of total deaths around the world. Around 54 percent of stroke and 47 percent of coronary heart disease are attributable to high BP.
While certain unmodifiable risk factors, such as age, ethnicity, and some existing health conditions can increase a person’s potential for developing hypertension, there are also a number of lifestyle changes — including losing weight, eating healthy, lowering salt intake, exercising, and not smoking — that can help reduce that risk.
Early detection, adequate treatment, and good control of high blood pressure can lower the risk of complications associated with hypertension. However, early detection of BP is difficult as high blood pressure does not cause any visible symptoms. Currently early diagnosis of high BP is limited to undergoing a screening for hypertension.
Now, researchers from Queen Mary University of London in the United Kingdom say that genetic signals could help doctors identify those at risk of developing high blood pressure early on in their lives.
For their study, researchers analyzed genetic data on more than one million individuals from the UK Biobank, the International Consortium for Blood Pressure, the United States Department of Veterans Affairs’ Million Veteran Program, and Vanderbilt University Medical Center’s biorepository.
The study identified 113 novel regions of the human genome, also known as genomic loci. They also found more than 2,000 independent genetic signals for blood pressure across all loci. They noted that although many genetic variants within the same ‘locus’ — a specifically defined region on a chromosome — will be similar, their study found many examples of ‘loci,’ which contain multiple, independent, distinct ‘signals’.
Blood pressure is a highly polygenic trait, meaning that it is influenced by thousands of different genetic variants, and each of these genetic variants will only have a small effect on increasing or decreasing blood pressure levels. However, if all the effects of all associated genetic variants are combined into one single aggregated risk score, which the researchers called a polygenic risk score, it could indicate larger effects on blood pressure.
A polygenic risk score essentially gives each person a score, according to how many risk variants they carry. Knowing someone’s genetic risk score would enable a doctor to know if the patient was in the high genetic risk group.
By using polygenic risk scores, scientists said they found that study participants with the highest genetic risk for hypertension have mean systolic blood pressure levels that are about 17 millimeters of mercury (mmHg) higher than those with the lowest genetic risk. The highest genetic risk group also has a seven-times likelihood of developing high blood pressure compared to those with the lowest genetic risk.
A main benefit in knowing genetic risk is that our genes are fixed at birth, so the genetic risk score is the same fixed value throughout life. Calculating people’s genetic risk scores before middle-age, when generally other lifestyle risks tend to increase, doctors would be able to target patients at higher genetic risk and recommend earlier lifestyle or therapeutic interventions.
Early detection could help reduce blood pressure before it begins to impact health, and thereby lessen the risk of cardiovascular disease in future. Researchers believe that more knowledge about how genetics impact a person’s blood pressure will ultimately help predict those at risk of high blood pressure in the future
