WASHINGTON — You know your cholesterol, your blood pressure … your heart gene score? Researchers say a new way of analyzing genetic test data may one day help identify people at high risk of a youthful heart attack in time to help.

Today, gene testing mostly focuses on rare mutations in one or a few genes, like those that cause cystic fibrosis or sickle cell disease, or the BRCA gene responsible for a small fraction of breast cancer. It is less useful for some of the most common diseases, such as heart disease or diabetes, because they are influenced by vast numbers of genes-gone-wrong working together.

Researchers reported a new way to measure millions of small genetic variations that add up to cause harm, letting them calculate someone’s inherited risk for the most common form of heart disease and four other serious disorders. They estimated that up to 25 million Americans may have triple the average person’s risk for coronary artery disease.

“What I foresee is in five years, each person will know this risk number, this ‘polygenic risk score,’ similar to the way each person knows his or her cholesterol,” said Dr. Sekar Kathiresan, who led the research team from the Broad Institute, Massachusetts General Hospital and Harvard Medical School.

If the approach pans out and doctors adopt it, a bad score wouldn’t mean you’d get a disease, just that your genetic makeup increases the chance – one more piece of information in deciding care. For example, when the researchers tested the system using a DNA database from Britain, less than 1 percent of people with the lowest risk scores were diagnosed with coronary artery disease, compared to 11 percent of people with the highest risk score.

On the flip side, a low-risk score “doesn’t give you a free pass,” he said. An unhealthy lifestyle could overwhelm the protection of good genes.