Genetic testing can determine if high cholesterol is inherited, study says

NEW YORK, Nov. 12 (UPI) -- Genetic testing can inform patients if they have an inherited form of high cholesterol and prompt them to have treatment that could help prevent a heart attack, stroke and possibly death, a new study says.

The findings of the study -- conducted at Intermountain Health in Salt Lake City -- were to be presented Sunday at the American Heart Association's Scientific Sessions 2023 in Philadelphia.

About 1 in 250 people have this condition -- familial hypercholesteremia, or FH -- that often presents without any signs until they experience a heart attack.

For these people, targeted medication therapy is needed because dietary or behavioral changes won't lower "bad" cholesterol levels, as the problem lies in their genes.

Most patients in the study already had tests that indicated high cholesterol, Stacey Knight, the study's lead author and a cardiovascular and genetic epidemiologist at Intermountain Health, told UPI in a telephone interview.

Knight added that people with unexplained high cholesterol should have genetic testing and pursue aggressive treatment that could reduce their risk of suffering a major cardiovascular event.

LDL, or low-density lipoprotein, cholesterol, sometimes called "bad" cholesterol, constitutes most of the body's cholesterol. High levels of LDL cholesterol raise the risk for heart disease and stroke by causing plaque, or fatty deposits, to accumulate in the blood vessels, according to the National Heart, Lung and Blood Institute.

But high levels of "good" HDL cholesterol may decrease the risk for health problems by transporting cholesterol and plaque buildup from the arteries to the liver, so they can be flushed out of the body.

"There is medication that can lower [people's] LDL cholesterol, and therefore, prevent them from having a heart attack or stroke," Knight said.

She cited guidelines from the American Academy of Pediatrics, which recommend that all children be screened between age 9 and 11 and again between age 17 and 21 for dyslipidemia -- unhealthy levels of one or more kinds of lipid in the blood.

"We need to intervene for people who have [this inherited form of high cholesterol] as early as possible," Knight said, adding that building up plaque at a young age can lead to an early heart attack, stroke or death.

The study's findings come from the HerediGene: Population Study, one of the world's largest DNA mapping initiatives, which is a partnership between Intermountain Health and Icelandic company deCODE. Its goal is to discover new connections between genetics and human disease.

In the study, researchers looked at the first 32,159 sequenced patients, and found 157 with a pathogenic or likely pathogenic variant in the LDLR gene.

Dr. Barry London, a professor and director of the division of cardiovascular medicine at University of Iowa Health Care in Iowa City, told UPI in a telephone interview that carrying a mutation in this gene means there is a 50% chance that a person's offspring will inherit it.

"If you have this genetic condition, you want to test family members and treat early in family members who carry it," London said, adding that people with the condition will often have blocked arteries in their 40s or even younger.

Screening for additional genetic mutations may identify even more at-risk patients, Dr. Robert Nierzwicki, a cardiologist at Northwestern Medicine Central DuPage Hospital in Winfield, Ill., told UPI via email.

A lifetime of being untreated for this condition can raise the overall risk of a cardiovascular event such as a heart attack 10 to 20 times the normal population's risk, Nierzwicki said.

Genetic testing for this inherited condition "is under-utilized, leading to many individuals with [this condition] being unaware of their own cardiac risks or the risks for their family members," he said. Meanwhile, nations with "screening programs have shown a significant reduction in cardiac events by identifying at-risk individuals early in life."

Rebecca VanDyke, a licensed certified genetic counselor at Northwestern Medicine Bluhm Cardiovascular Institute in Chicago, told UPI via email that "there can be a lot of variability in the severity of symptoms" in patients with this inherited condition. That makes it more difficult to know who may suffer a heart attack or a stroke or die suddenly.

"Genetic testing can help us identify individuals with [this condition] that routine cholesterol screening might miss."

If someone is concerned about their personal or family history of high cholesterol, she said they should consider consulting with a lipid specialist or a genetic professional to find out if genetic testing is appropriate.