Molecular Genetics Hypercholesterolemia Panel

Familial hypercholesterolemia (FH) is an inherited disorder characterized by severely elevated LDL cholesterol (LDL-C) levels that cause atherosclerotic plaque deposition in arteries. Persons with untreated FH are at an approximately 20-fold increased risk for coronary heart disease (CHD), which may manifest as angina, myocardial infarction, or stroke. Two types of FH can occur: Heterozygous FH (HeFH) and Homozygous FH (HoFH). HeFH results from a single pathogenic variant and is relatively common (prevalence 1:200-500). HoFH results from either two pathogenic variants in a single gene or one pathogenic variant in each of two different genes. HoFH is much rarer with a prevalence of 1:160,000 to 1:1,000,000. Most individuals with HoFH experience severe CHD by their mid-20s and the rate of either death or coronary bypass surgery by the teenage years is high. This next-generation sequencing test is designed to detect mutations in the coding region of 4 genes associated with Hypercholesterolemia.

 Reasons for Referral:

• Elevated LDL cholesterol.
• Clinical presentation consistent with hypercholesterolemia including atherosclerotic plaque deposition or CHD.
• Positive family history for hypercholesterolemia (targeted testing is available if familial mutation is known).
• Carrier testing.

Next generation sequencing using Illumina NextSeq 500/550 technology of the 4 Hypercholesterolemia-associated genes listed below. Samples are prepared using hybridization probes to enrich exonic regions.  This assay does not assess regions of insufficient coverage, introns and promoter regions; pseudogenes; where the reference genome is inaccurate or contains gaps and insertions; and regions of high GC or polynucleotide repeats, but may contain variants that impact gene function.

Exon-level deletion/duplication analysis is performed by running the NGS data through the Genome Analysis Toolkit (GATK) Germline Copy Number Variation best practices pipeline from GATK, version 4.1.4.1. A Bayesian model was validated clinically in our lab. The model can detect copy changes at a resolution of three (3) or more probe targets (exons) for deletions and duplications in genes that do not have pseudogenes, and is not designed to detect low-level mosaicism or balanced alterations.

Hypercholesterolemia (4 genes):  APOB, LDLR, LDLRAP1, PCSK9

Blood: EDTA or ACD (Solution A or B):

• Adult: 5 mL
• Child: 5 mL
• Infant: 2-3 mL

Saliva: 2 ORAgene™ Saliva Collection Kits (OGR-500) used according to manufacturer instructions.  Please contact KDL Client Services for a Saliva Collection Kit for patients that cannot provide a blood sample.

Assisted Saliva: 4 ORAgene™ Assisted Saliva Collection Kits (OGR-575) used according to manufacturer instructions.  Please contact KDL Client Services for an Assisted Saliva Collection Kit for patients that cannot provide a blood sample.

Skin Fibroblast: Punch Biopsy (Cell cultures will be prepared at KDL and used for testing), or 2 T-25 confluent flasks

DNA: 5-10µg at 60-100ng/uL (DNA must be extracted in a CLIA-certified laboratory or a laboratory meeting equivalent requirements as determined by the CAP and/or CMS)

Prenatal: 

• Direct Amniotic Fluid (10-20mL)
• Direct CVS
• Direct POC
• Cultured Amniocytes (2 T-25 flasks)
• Cultured CVS (2 T-25 flasks)
• Cultured Fetal Tissue: Product of Conception (2 T-25 flasks)
• Cord Blood (1-2mL)

Notice Regarding Molecular Genetic Testing on CVS or Amniotic Fluid Specimens:

Maternal cell rule-out testing will be performed on all prenatal specimens received. Please provide maternal blood (or saliva) in addition to the fetal specimen. Additional charges apply for the maternal cell rule-out test.

For routine testing of blood and saliva (or DNA extracted from them), KDL does NOT accept samples from patients within two (2) weeks of a packed cell/platelet transfusion or within four (4) weeks of a whole blood transfusion.  For extraordinary circumstances, where testing must be performed outside of the above windows, please contact our lab.

A REQUISITION FORM MUST ACCOMPANY ALL SAMPLES.  Please include detailed clinical information, including ethnicity, clinical history, and family history.

Weekly

6-8 weeks

• Package and ship specimen to remain cold, but not frozen. 
• Ship via overnight express, using the FedEx priority overnight label provided. 
• Contact Client Services for shipping kits and instructions at (855) 535-1522.

1. GeneReviews:      

         a. Youngblom et al., 2014,http://www.ncbi.nlm.nih.gov/books/NBK174884/