Genetic testing is believed to increase the number of people diagnosed with familial hypercholesterolemia (FH), which is an inherited condition that causes very high blood levels of low-density lipoprotein (LDL) cholesterol from birth. People with a family history of the condition and/or very high blood levels of LDL cholesterol should be tested for FH, according to a panel of experts. The improved diagnosis of FH offered by genetic testing can help more people receive appropriate treatment sooner. A consensus statement on FH was recently published in the Journal of the American College of Cardiology by the expert panel, which was convened by the FH Foundation.
People with FH (also known as autosomal dominant hypercholesterolemia) have an increased risk of heart disease and stroke because of the long-term effects of high LDL cholesterol in the blood. Extra cholesterol in blood can be deposited in blood vessel walls, forming plaques that can narrow or eventually block the opening of blood vessels. People with FH are typically treated with statins to lower LDL cholesterol levels and decrease their heart disease risk.
According to the FH Foundation, the condition affects roughly 1 in 200 people in the U.S. and affects over 30 million people worldwide, yet the vast majority (about 90%) go undiagnosed and inadequately cared for. FH causes 20% of the heart attacks in people aged 20 to 40 and is the cause of heart attacks and surgical procedures to open blockages in half of all men with FH before they reach the age of 50, and in a third of all women with FH before they reach the age of 60.
FH can be diagnosed based on a person's LDL cholesterol levels coupled with a family history of high LDL cholesterol levels and heart disease, but genetic testing for the condition is underutilized, according to the expert panel. The value of genetic testing is that it provides a definitive diagnosis, encourages more families of those with FH to get screened, and is likely to result in people at risk starting treatment earlier than they might have. Genetic testing can also improve assessment of an individual's personal risk of a heart attack or stroke based on the specific test results. For example, certain genetic changes cause a substantially higher risk and need more intensive treatment in order to lower LDL cholesterol to safe levels.
The consensus statement recommends that people with persistent very high LDL cholesterol levels (above 190 mg/dL for children and above 250 mg/dL for adults) should undergo genetic counseling and be offered FH genetic screening even if there is no family history of heart attacks or high cholesterol.
For people with a family history of high cholesterol or early heart attack and a personal history of persistently elevated LDL cholesterol (above 160 mg/dL for children and above 190 mg/dL for adults), genetic counseling and FH genetic testing can be considered.
These individuals would be tested for mutations in three genes that cause most FH cases. The genes are:
- LDLR (Low Density Lipoprotein Receptor)
- APOB (Apolipoprotein B)
- PCSK9 (Proprotein Convertase Subtilisin/Kexin type 9)
First degree relatives (parent, child, sibling) of anyone who tests positive for a disease-causing mutation should also receive genetic counseling and be offered testing for the familial mutation.
"Diagnosing and treating FH in childhood reduces the risk of early heart disease by about 80 percent, which is why it’s so important to find families with FH and especially children who have this invisible, life-threatening genetic disorder," said Amy C. Sturm, M.S., C.G.C., Genomic Medicine Institute, Geisinger, and a co-author of the consensus statement. "In addition, understanding the exact genetic mutation can better inform the initiation and treatment of FH with more intense lipid-lowering [drugs] and ultimately improve outcomes," said Ms. Sturm.
People who are offered FH genetic testing may want to check with their insurance companies to determine whether such testing would be covered by their plan.