By AMERICAN HEART ASSOCIATION NEWS
Editor’s Note: This is the fourth in a series of stories explaining how the scientific research underway in the Cardiovascular Genome-Phenome Study can save and improve lives.
Day after day at a Veterans Affairs hospital in Florida where Donna Arnett, Ph.D., worked as a research nurse in the field of hypertension, she’d see men on their way to the dialysis unit. Most of them were African-American.
Back then, Arnett was surprised by the impact of high blood pressure on African-Americans’ hearts and kidneys. More recently, through her imaging research, she found that African-Americans often have thicker heart muscles than their white counterparts.
This spurred Arnett to study how genetic factors influence blood pressure and heart structure in African-Americans. The prevalence of high blood pressure in African-Americans is among the highest in the world, affecting nearly half of African-American adults in the U.S., according to 2015 statistics from the American Heart Association.
Arnett, chair of the department of epidemiology at the University of Alabama at Birmingham School of Public Health and a past president of AHA, is one of eight researchers recently awarded $500,000 as part of the AHA’s Cardiovascular Genome-Phenome Study.
CVGPS researchers are using massive amounts of data pooled from major studies to speed the discovery of personalized treatments and prevention for heart disease and stroke, the leading causes of death worldwide.
Arnett recently explained her research to AHA News.
What do we know about how genes affect the heart? “After conception, when the heart is developing, there is a set of genes that governs the growth of the heart. In adulthood, these genes are no longer active. But in some diseases, like enlargement of the heart in response to high blood pressure, this set of genes is reactivated. We believe that the epigenome — a set of chemical factors that helps regulate the behavior of genes — controls the reactivation.”
How do genes specifically influence heart disease? “We know from previous research that sequence variation — the ordering of the links in the DNA chain — influences cardiovascular diseases.
The DNA in our cells can be thought of as a chain with some three billion links, and each link can be represented by the letter A, T, G or C. Sections of this chain are individual genes, and the order of links encodes the instructions that tell our body how to make things like muscles and hormones. Just a one-letter variation — like swapping a T for a G — may change the way heart muscle is manufactured and spell the difference between developing heart failure or not.
But just like computer programs, genes can do their thing only when they are ‘running.’ Genes can be switched off or on when they shouldn’t be. A gene that is turned off may not make a particular hormone, for example, which may predispose a person to heart failure. This is an epigenetic process, and this is the focus of our study.”
How do you plan to uncover the key genetic factors? “In the next six months we’ll use specimens from African-Americans participating in the HyperGEN (Hypertension Genetic Epidemiology Network) study to look for areas of the genome where epigenetic factors are correlated with thicker heart muscles.
Then we will work with the Jackson Heart Study, the largest study in history to focus on the genetic factors related to cardiovascular diseases in African-Americans, to evaluate these regions of the genome using blood samples from participants. Any regions that are found in the HyperGEN study and confirmed in the Jackson Heart Study will be explored in the Framingham Heart Study (the nation’s largest and longest-running heart study) using data already collected.”
For now, what can people do to protect themselves from cardiovascular diseases? “Because many forms of heart disease occur later in life, many people don’t realize the importance of sustaining your health — and your heart — as you age.
Taking steps to ensure that high blood pressure doesn’t develop is important, even in childhood. Developing and maintaining healthy habits, like eating a diet with lots of vegetables, fruits and whole grains, being physically active, staying lean and not smoking can keep hypertension and heart disease from developing. Your health is your own renewable resource — protect it.”