Can you tell me more about Familial Hypercholesterolemia?
A curious adult from California asks:
“My husband was recently diagnosed with FH-Familial Hypercholesterolemia. I’m concerned that the extremely high cholesterol levels will lead to medical problems. Can you tell me more about FH?”
I am sorry to hear about your husband’s diagnosis. To learn more about how he might be affected by his condition and how to stay in good health, he should talk to his doctor.
Familial Hypercholesterolemia or FH is a genetic disease where you get really high levels of the bad cholesterol, called LDL cholesterol. If left untreated, high levels of LDL can lead to early heart attack and stroke.
With FH, the bad cholesterol builds up in the blood because the liver isn’t working quite right. One of the liver’s jobs is to filter out any extra LDL in the blood and get rid of it. The liver does this using a protein called LDLR (Low Density Lipoprotein Receptor).
People with FH often have a mutation or change in the DNA of their LDLR gene. This DNA change mucks up the instructions in the gene so that a broken LDLR protein gets made. When it is broken, the LDLR protein can't do its job and the bad cholesterol builds up in the blood.
All of this extra LDL leads to cholesterol being deposited on the inside of the arteries. There, it can stop the blood from flowing and cause a heart attack or stroke.
How high your cholesterol will be is partly determined by whether you have one or two bad copies of the LDLR gene. (Remember, we have two copies of most of our genes – one from mom and one from dad.)
As you might expect, having two bad copies is much worse than having one. If you have one working copy of the LDLR gene, then you'll have some LDLR protein that can do its job.
People with two bad copies sometimes don’t live past the age of 30 unless they are diagnosed early. Fortunately, this is pretty uncommon as only about 1 in a million people have two bad copies.
Having one bad copy is much more common – around 1 in 500 or so. The statistics I’ve seen are that when left untreated, men with the disorder typically have heart attacks in their 40’s and 50’s – 85% have heart attacks by age 60.
What this means is that your husband is at a high risk for a heart attack or stroke. Luckily, there are things he can do to improve his odds.
Someone with FH needs to eat right and exercise and, if they smoke, stop. If they have high blood pressure, they should take steps to control it.
Having said all of this, these lifestyle changes are often not enough in FH cases. People with FH may have to go on some cholesterol lowering drugs called statins. Statins work by having the liver make less LDL (that's right, the liver makes LDL and clears it away too!).
I hope this helped you better understand FH. Again, for any advice about FH, it is useful for you to talk more with your doctor or to see a genetic counselor.
Author: Dr. Barry Starr
Barry served as The Tech Geneticist from 2002-2018. He founded Ask-a-Geneticist, answered thousands of questions submitted by people from all around the world, and oversaw and edited all articles published during his tenure. AAG is part of the Stanford at The Tech program, which brings Stanford scientists to The Tech to answer questions for this site, as well as to run science activities with visitors at The Tech Interactive in downtown San Jose.