If you have high cholesterol, many factors may be contributing to the cause. Poor diet, lack of exercise, smoking, and too much drinking all can alter your cholesterol levels, which can put you at risk of heart disease, the No. 1 cause of death in the United States, according to the Centers for Disease Control and Prevention (CDC).

But what if you were already at risk at birth?

Inherited high cholesterol, scientifically known as familial hypercholesterolemia or FH, is a genetic form of high cholesterol that can pass from parent to child. From birth, those with FH produce more cholesterol than their body can safely handle, causing a buildup of fat and plaque in the arteries that can cause severe problems in the future.

Do you or does someone you know have FH? Here are nine things you need to know.

Your Body Needs Cholesterol

Cholesterol is not the villain in this story. Your body needs cholesterol to build healthy cells properly, and part of your liver’s job is to make all the cholesterol your body needs. But there are different types of cholesterol: high-density lipoprotein and low-density lipoprotein.

“A good way to remember the different types of cholesterol is HDL, or H for happy,” says Leslie Cho, MD, the director of the Cleveland Clinic Women’s Cardiovascular Center. “Then there is bad cholesterol called LDL — L for lousy.”

HDL absorbs cholesterol and carries it back to the liver, flushing it from the body. LDL makes up the bulk of the cholesterol in your body and builds up in plaque on the walls of your blood vessels, constricting blood flow to your heart and other organs.

FH Plays a Trick on the Liver

FH is caused by faulty LDL receptors that can’t cycle cholesterol from the bloodstream through the liver.

But that’s only part of the problem. FH convinces the liver that the body isn’t getting any cholesterol, which forces the liver to manufacture more of its own cholesterol and signals to the intestine to absorb more cholesterol than it usually would because of this perceived scarcity.

This makes it extremely difficult for people with FH to get their cholesterol down. No amount of diet, exercise, or good lifestyle choices can stop the liver from producing more cholesterol.

It’s a Family Affair

If a parent has familial hypercholesterolemia, there is a 50 percent chance a child will inherit the LDL abnormality, known as heterozygous FH.

In rare cases, if both parents have FH, there is a 25 percent chance the child will inherit the FH gene from both of them, known as homozygous FH, the most severe case of high cholesterol, which can develop into heart disease as early as the preteen years.

Cardiologists can perform cascade screenings to reduce guesswork, which means they screen all the first-degree relatives of their initial FH patient.

“I think about my patients with the most severe form of this disorder. I know how many kids they all have,” says James Underberg, MD, a clinical assistant professor at the NYU Grossman School of Medicine in New York City and the president of the National Lipid Association.

“I'm taking care of their family by keeping the patient healthy,” Dr. Underberg explains. “I'm taking care of the kids who may also have the disorder. We tend to take care of families of patients.”

Symptoms Are Few and Mild

Most people don’t have FH symptoms, which makes going undiagnosed so dangerous.

But some people have cholesterol deposits that develop into small bumps around their eyes or tendons.

Some people younger than 45 may also notice a white ring around the eye's cornea, known as a corneal arcus. Typically, it appears as a half-moon on the bottom or top of the cornea, which means you can miss it if it's hidden by your eyelid.

Dr. Cho says the best way to determine if you should get tested is simply to evaluate your family’s history with cholesterol.

More People Have FH Than You Think

More than a third of the population has high cholesterol, according to the CDC, and about 1 in 200 adults are affected by FH in the general population. That means about 1.3 million people in the United States have FH, including children.

FH is frequently diagnosed in insular communities, such as Ashkenazi Jews, Dutch Afrikaners, and French Canadians, who have a greater chance of passing FH among themselves.

Underberg says that FH does not affect any particular race, ethnicity, or gender differently from any other. But in a review published in Circulation in May 2020, researchers found that 60 percent of studies and over 80 percent of reported FH cases are from Europe, with no representation from Southeast Asia and Africa, suggesting that further research is needed on racial disparity.

Undiagnosed FH Can Mean Early Heart Disease for Some

If left undiagnosed and untreated, people with FH have a 20 times greater risk of developing heart disease, according to the American Heart Association. Patients are also susceptible to peripheral vascular disease and stroke much earlier than the general population.

Half of the men with untreated FH will have a heart attack before turning 50, and may have one as early as their twenties. Coronary heart disease in women can appear up to 30 years earlier than usual, and 30 percent of untreated women will have a heart attack before they turn 60, according to the American Heart Association.

FH Is Treatable

While a healthy lifestyle cannot fix familial hypercholesterolemia alone, it is still strongly encouraged. This means following a low-fat diet like the Mediterranean diet or a plant-based diet, and getting about 30 minutes a day of moderate exercise such as brisk walking, running, cycling, or any activity that you enjoy and keeps you moving. It also means ditching bad habits like smoking or drinking too much alcohol.

Statin medications are another layer of treatment for FH. These include PCSK9 inhibitors like Praluent, which lower total cholesterol; ezetimibe (Zetia), which decreases cholesterol absorption in the intestine; and bile acid sequestrants like cholestyramine or colestipol, which lower LDL cholesterol.

Another class of drugs that work by blocking the production of cholesterol in the liver are adenosine triphosphate-citrate lyase (ACL) inhibitors. These are used as a primary prevention of high cholesterol in individuals with heterozygous FH. Bempedoic acid (Nexletol) is the only ACL inhibitor approved by the U.S. Food and Drug Administration (FDA) for reducing LDL cholesterol in this population.

But cholesterol in some individuals can be so high that medication doesn’t work. For them, a nonsurgical therapy called LDL apheresis can be performed every two weeks to remove cholesterol from the blood, similar to dialysis.

A study in the July 2018 Frontiers in Pharmacology identified 14 treatment options for FH ranging from diet to fish oils to genetic therapy. It also found that both children and adults should receive similar treatments. Ultimately, for most people with FH, treatment is some combination of “all of the above.”

“Lifestyle and exercise are good not just for the heart, but it's good for your whole life,” says Cho. “Just because you're taking cholesterol medicine doesn't mean you are done and you can eat whatever the heck you want. Your body is all one connected thing.”

It’s Okay to Treat Young Children

Often, medical treatment is a last resort for children with any condition. But for FH, the earlier treatment happens, the better.

A review published in the Journal of the American Heart Association found that universal lipid screening is recommended in children as early as age 2 for families with a history of high cholesterol and screenings around ages 9 to 11 for everyone else. But only one-third of practicing pediatricians have adopted these recommendations, even though earlier detection means a smaller chance people with FH will need to rely on medication and therapies.

The study found that statins are effective and FDA-approved for children in need of more advanced treatment. Pravastatin and pitavastatin are approved for children age 8 and older, whereas the five other statins on the market are FDA-approved from the age of 10.

Underberg says early diagnosis and treatment are akin to getting a car to a mechanic right away instead of waiting for it to break down.

“It's the same with cholesterol management in these patients,” says Underberg. “If you treat it when the kids are young, you reduce the risk early in life so aggressively that later in life, you don't have to do as much.”

We Know More Now About FH Than Ever Before

Reputable sources like the American Heart Association and advocacy groups like the Family Heart Foundation and Underberg’s National Lipid Association are committed to informing and studying FH through continuing research, which has already pushed the limits of what we know much further than before.

“I would tell you the last 10 years has really been a boom time for awareness around FH, and part of it is because of the emergence of new therapeutics,” says Underberg. “In my lifetime, I've seen this disease go from something that could kill you by the age of 15 to something where you can expect to live a lifetime if treated early and appropriately.”