Molecular Genetics Connective Tissue Panel

The inherited connective tissue disorders comprise a group of genetically heterogeneous diseases including: Marfan syndrome, Loeys-Dietz syndrome, and Ehlers-Danlos syndrome. This group of disorders primarily affects the skeletal and cardiovascular systems.  Marfan syndrome is a clinically variable disorder involving the cardiovascular, ocular, and skeletal systems. Primary manifestations for Marfan syndrome include aortic dilation and/or dissection, myopia, retinal detachment, glaucoma, bone overgrowth, and joint laxity. Loeys-Dietz syndrome is characterized by skeletal abnormalities with aneurysms and/or dissections of the cerebral, thoracic, and abdominal arteries. Ehlers-Danlos syndrome is a disorder defined by smooth, hyperelastic skin, abnormal wound healing and bruising, joint hypermobility, and risk for arterial rupture. This next-generation sequencing test is designed to detect mutations in the coding region of 31 genes associated with Connective Tissue Disorders.

Reasons for Referral:

• Aortic or arterial aneurysms and/or dissections.
• Clinical presentation consistent with Marfan syndrome, Loeys-Dietz Syndrome, or Ehlers-Danlos Syndrome.
• Positive family history for connective tissue disorders (targeted testing is available if familial mutation is known).
• Carrier testing.

Next generation sequencing (NGS) will analyze the exons or coding regions of the genes using Illumina NextSeq 500/550 technology and preparing samples 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.

• 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 an Assisted 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: 3-4µg at a minimum of 50-100ng/µL (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 Prenatal Specimens:

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

For routine testing of blood, saliva and buccal swabs, 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

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:
   1. Dietz, 2014, http://www.ncbi.nlm.nih.gov/books/NBK1335/
   2. Loeys et al., 2013, http://www.ncbi.nlm.nih.gov/books/NBK1133/
   3. Malfait et al., 2011, http://www.ncbi.nlm.nih.gov/books/NBK1244/ 
2. Genetics Home Reference:
   1. http://ghr.nlm.nih.gov/condition/marfan-syndrome
   2. http://ghr.nlm.nih.gov/condition/loeys-dietz-syndrome
   3. http://ghr.nlm.nih.gov/condition/ehlers-danlos-syndrome