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Early-onset Coronary Heart Disease/Familial Hypercholesterolemia: LDLR (Full Gene Sequencing)

Test Includes This test covers all coding nucleotides of gene LDLR, plus at least two and typically 20 flanking intronic nucleotides upstream and downstream of each coding exon, covering the conserved donor and acceptor splice sites, as well as typically 20 flanking nucleotides in the 5′ and 3′ UTR.
Special Instructions In cases in which a known mutation can be documented, the physician may prefer to order test 252640.

Test orders must include an attestation that the provider has the patient’s informed consent for genetic testing. See sample physician office consent form: Consent for Genetic Testing. In the case of family tests (ie, known mutations), Correlagen requires the result report of the first patient tested in the family (the index case), if not performed at Correlagen. Other family members are subsequently tested for the specific mutation found in the first patient tested.
Specimen Whole blood; DNA is accepted (Call 866-647-0735 for DNA collection information.)
Volume 2 mL
Container Lavender-top (EDTA) tube
Collection Samples may be stored for brief periods at 4°C. Ship overnight at room temperature.
Storage Instructions Maintain specimen at room temperature.
Causes for Rejection Container broken or leaking; container not labeled or label not legible
Reference Interval Normal equals reference sequence or variants that are known or predicted to be benign; abnormal equals all other variants.
Use Confirm a clinical diagnosis of familial hypercholesterolemia; allow early diagnosis in family members, guiding use of pharmacological treatment in children
Limitations This method does not reliably detect mosaic variants; large deletions; large duplications, inversions, or other rearrangements; or deep intronic variants. It may be affected by allele dropout, it may not allow determination of the exact numbers of T/A or microsatellite repeats, and it does not allow any conclusion as to whether two heterozygous variants are present on the same or on different chromosome copies.

This test was developed, and its performance characteristics determined, by LabCorp. It has not been cleared or approved by the US Food and Drug Administration (FDA). The FDA has determined that such clearance or approval is not necessary.
Methodology DNA sequencing
Additional Information Early-onset coronary artery disease (EO-CAD) is a common, progressive heart disease caused by atherosclerosis and is the leading cause of morbidity and mortality in the United States. A major risk factor for EO-CAD is hypercholesterolemia, a common lipid disorder, which is familial in about 10% cases. Mutations in LDLR account for >80% of familial hypercholesterolemia (FH), and mutation carriers typically have 90% to 100% risk of developing symptoms. Genetic testing can confirm a clinical diagnosis of FH/EO-CAD and allow for accurate identification of presymptomatic mutation carriers within affected families.
References Mayer B, Erdmann J, Schunkert H. Genetics and heritability of coronary artery disease and myocardial infarction, 2007. Clin Res Cardiol. 2007 Jan; 96(1):1-7. PubMed 17021678

Varret M, Abifadel M, Rabès JP, Boileau C. Genetic heterogeneity of autosomal dominant hypercholesterolemia. Clin Genet. 2008 Jan; 73(1):1-13. PubMed 18028451