Familial Hypercholesterolemia (FH)

Updated:Sep 8,2017

Cholesterol in the family
What is it?

Familial hypercholesterolemia (FH) is an inherited defect in how the body recycles LDL cholesterol. LDL levels in the blood remain very high — in untreated adults, above 190 milligrams per deciliter (mg/dL) of blood. 

Everyone’s cholesterol levels tend to rise with age, but people with FH are basically born with high cholesterol — and as time passes, it gets worse.

familyOver time atherosclerotic plaques develop, leading to a much-higher-than-normal risk of coronary heart disease. Compared to people with average LDL cholesterol levels (less than 130 mg/dL), people with FH have a five times higher risk for coronary heart disease over 30 years.

Men with FH get coronary heart disease up to 20 years earlier. Half of men with untreated FH will have a heart attack or angina before they’re 50. For some it will be as early as their 20s.

In women, coronary heart disease appears up to 30 years earlier. Thirty percent of untreated women will have a heart attack before they’re 60.

These increased risks are independent of other risk factors.

How common is it?
About 1.5 million Americans have the FH genetic mutation. That’s one in 250 adults (an estimated 834,000 people), according to results from the 1999-2012 National Health and Nutrition Examination Survey (NHANES). Men and women are affected equally.

How do you get it?
FH is inherited from one of your parents or, much less often, from both.

There are two types of FH – heterozygous and homozygous. Heterozygous FH occurs when the FH mutation is inherited from one parent.  

Homozygous FH occurs when the FH mutation is inherited from both parents. It’s much rarer.  People with this can have very high LDL cholesterol levels; many need bypass surgeries before adulthood. Without treatment, these people rarely live into their 20s.

If one person in a family has FH, it’s a good idea for all first degree relatives -- parents, siblings, children – to be checked for it.

All people should have their cholesterol tested starting at age 20, but It may be helpful for at-risk children to be evaluated between the ages of 6 and 12. Kids may be started on medication as early as age 8 or 10 if their cholesterol is high enough or if the family history makes it prudent. In teens, if there’s no evidence of FH and LDL levels are normal, it’s unlikely that FH will show up later.

Gene mutations
FH is caused by mutation in the gene for the LDL receptor, which is involved in LDL recycling. Mutations in other genes can also cause inherited high cholesterol. Those genes include the PCSK9 gene and the gene for Apolipoprotein B.

All these genes are connected with one another. If you inherit a specific type of mutation in any of these three genes, you can develop FH or inherited high cholesterol.
  
How is it diagnosed?
If someone in your family has had an early heart attack, it’s wise for everyone to be checked.

FH is often diagnosed based on a combination of laboratory results, physical exam findings and personal and family history. Discovery through molecular diagnosis, genetic diagnosis or genetic testing is also possible. 

Genetic tests don’t always find a mutation when FH is present. However, when they do, it can be very helpful for the person who has it and their relatives. 

Sometimes people with FH have physical symptoms, although many don’t. One symptom is cholesterol deposits in the Achilles tendons or the tendons of the hands or elbows. People with FH can also develop cholesterol deposits in unusual places, like around their eyes. Such visual characteristics are why FH was once classified as a dermatological disease.

How is it treated?
People with FH have an excellent prognosis — when they’re identified early enough and treated aggressively enough.

FH can’t be treated by diet and exercise alone. These lifestyle changes will lower LDL, but when levels must be lowered by 50 or 75 percent, medication is needed.

Treatment usually involves a statin drug. Often FH patients require more than one medication, and sometimes more than two. When statins don’t lower cholesterol enough, more cholesterol-lowering medications like ezetimibe are used. People with extremely high LDL, like those with the homozygous form, may undergo LDL apheresis. This is a dialysis-like procedure that’s done every few weeks to remove cholesterol from the blood.

Another class of lipid-lowering medications (bile acid sequestrants) like cholestyramine or colesevelam may also be used. They reduce the amount of cholesterol absorbed by the intestines. This lowers the amount of cholesterol that gets into the blood.

Two PCSK9 inhibitors are newly developed injectable antibodies that lower cholesterol levels. They target and block the PCSK9 protein. This makes more receptors on the liver available to remove LDL cholesterol from blood. Although FDA-approved, they’re still a new, costly treatment with limited use.
 


This content was last reviewed April 2017.
 

 


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