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Familial Hypercholesterolemia (FH) Single Site

Test code(s) 94878

Question 1. What is this test used for?

This test is used to determine whether a patient has a certain variant at a single site within the LDLR, APOB, or PCSK9 genes. Variants in the LDLR, APOB, and PCSK9 genes have been associated with familial hypercholesterolemia (FH). A genetic test report from a family member(s) with a previously identified variant(s) is required to perform this test. The test is capable of detecting point mutations as well as deletions/duplications, based on family member test results.

Question 2. Who is this test appropriate for?

This test may be appropriate for patients with a family history of a known variant(s) in the LDLR, APOB, or PCSK9 genes. Variants in these (and other) genes have been associated with FH. Official test results of the family member must be submitted for laboratory review. For more information or to discuss the family history with a Quest Diagnostics genetic counselor, please call Quest Genomics Client Services at 1.866.GENE.INFO.

Informed consent following genetic counseling is strongly recommended.

Question 3. What test should I request if the patient does not have a relative with FH genetic test results?

When FH is suspected and no previous LDLR, APOB, or PCSK9 genetic test result from a family member is available, the Familial Hypercholesterolemia (FH) Panel (Test Code 94877) is the appropriate test to order.

The Familial Hypercholesterolemia (FH) Panel is appropriate for individuals with a personal history of hypercholesterolemia based on the Simon Broome criteria,1 Dutch Lipid Clinic Network criteria,2 or US MedPed Program criteria3; a personal or family history of cardiovascular disease or coronary artery disease at a young age; or a personal or family history of tendon xanthomas or corneal arcus.

Question 4. Whom can I ask for help regarding a specific case?

You can ask one of our genetic counselors. Please call Quest Genomics Client Services at 1.866.GENE.INFO to speak with a genetic counselor.

Question 5. My patient has a positive result. What does this mean?

A patient is considered to have a positive result when at least one pathogenic or likely pathogenic variant has been detected.  The presence of a single pathogenic variant is causative of FH. Individuals with FH are at risk of developing high levels of LDL cholesterol (LDL-C), which may increase the risk for premature coronary artery disease and myocardial infarction. Patientswith FH may also develop visible lipid deposits in the tendons (tendon xanthoma) or eyes (corneal arcus). Individuals with FH may have either heterozygous FH (HeFH) or homozygous FH (HoFH). Patients with HoFH tend to have more severe symptoms or earlier onset as compared to those with HeFH.

The FH Foundation provides information and resources about FH (https://www.thefhfoundation.org). The National Lipid Association, and the European Artherosclerosis Society, also provide management guidelines. Consider referring the patient to a center experienced in treating patients with FH. Such a center can discuss treatment options with the patient. Genetic counseling for family members is advised.

Question 6. My patient has a negative result. What does this mean?

A negative result means that the familial variant was not found. Implications of this result depend on the patient’s personal medical history and family history:

  • Patient with elevated LDL-C levels. Your patient should continue to be managed based on current guidelines. In certain instances, it may be appropriate to test for other variants in the LDLR, APOB, or PCSK9 genes. Please call Quest Genomics Client Services at 1.866.GENE.INFO to discuss possible additional testing with a genetic counselor.
  • Patient without elevated LDL-C levels. Your patient is not at increased risk for hypercholesterolemia based on the result. The risk for hypercholesterolemia is based on his or her personal history.

References

  1. Scientific Steering Committee on behalf of The Simon Broome Register Group. The risk of fatal coronary heart disease in familial hypercholesterolemia. BMJ. 1991;303:893-896.
  2. World Health Organization (WHO). Familial hypercholesterolaemia (FH): report of a second WHO consultation. Geneva: World Health Organization; 1999.
  3. Williams RR, Hunt SC, Schumacher C, et al. Diagnosing heterozygous familial hypercholesterolemia using new practical criteria validated by molecular genetics. Am J Cardiol. 1993;72:171-176.
This FAQ is provided for informational purposes only and is not intended as medical advice. A clinician’s test selection and interpretation, diagnosis, and patient management decisions should be based on his/her education, clinical expertise, and assessment of the patient.
Document FAQS.197 Version: 0
Effective 03/19/2018 to present