Mater Pathology

Massively parallel sequencing for cardiac disorders

February 8, 2016

Mater Pathology is now offering one of the most comprehensive and clinically focussed NATA accredited cardiac genetic test panels currently available. Using 'massively parallel sequencing' technology we are able to simultaneously analyse an entire panel of genes associated with a particular cardiac disorder.

Our expert Genetic Pathologists provide comprehensive interpretation, reporting and advice to referring clinicians utilising this service.

Why do genetic testing for cardiac disorders?

Over  forty  cardiovascular disorders have been recognised  to be caused by genetic mutations [1].  Additionally, around 50% of cases with sudden cardiac arrest under 35 are related to inherited cardiac conditions [2].  Identifying a causative mutation may benefit patients by:

  • Providing a definitive diagnosis/explanation for why the disease has occurred
  • Informing patient treatment or management 
  • Allowing other at-risk family members to clarify and manage their risk
  • Facilitate reproductive options such as prenatal diagnosis from amniocentesis / chorionic villus sampling

Why test a ‘panel’ of genes?

The same cardiac condition may be caused by mutations in any of a number of different genes, while conversely, two people with a mutation in the same gene may present with different cardiac conditions.  Furthermore, some cardiac conditions are caused by a person having more than one mutation in the same or different gene [3].  Panel testing allows all possibilities to be covered simultaneously.  Massively parallel sequencing technology allows large panels of genes of interest to be sequenced simultaneously, significantly reducing the overall cost and time taken to complete such testing.  Importantly, the gene panels have been specifically designed to reduce the likelihood of generating ambiguous results by ensuring that only genes that are known to be associated with the presenting phenotype are analysed. 

Who should be tested?

The probability of identifying a disease causing gene change is higher in patients who have a confirmed clinical diagnosis [4], therefore testing should initially be performed on a family member who is clinically affected.  If a disease causing mutation is identified in that individual, other family members may then access testing to see if they carry the same mutation.  Prenatal testing may also be available through our laboratory for pathogenic variants if required (only available through a clinical genetics service).

What are the cardiac disorders covered by the panels?

The Mater cardiac panels consist of a range of cardiomyopathy panels, arrhythmia panels, as well as a dyslipidaemia and an aortopathy panel. 

The cardiomyopathy tests include hypertrophic, dilated, arrhythmogenic and non-compaction cardiomyopathy subpanels, which can be requested separately or ordered together as part of the ‘comprehensive cardiomyopathy panel’.  The ‘arrhythmia’ tests include subpanels for QT abnormalities, Brugada syndrome, CPVT and Famillial Atrial Fibrilation disorders.  Other conditions covered by remaining panels include, but are not limited to, Familial Hypercholesterolaemia, Marfan syndrome, TAAD, Loeys-Diets syndrome and Ehlers-Danlos Type IV. Please see our online brochure for further details http://pathology.mater.org.au/cardiac.

What is the technology used and what are the limitations of the test?

The test is performed using the Illumina Miseq ‘next generation’ sequencing platform and the Illumina Trusight Cardio Kit with genes which were expertly selected with researchers from the Imperial College of London.  The assay will assess sequence variants in the coding regions of the genes in the appropriate subpanel, with >99% of targeted bases sequenced at >25X read depth. Copy number variations, large deletions or duplications, triplet repeat expansions, structural rearrangements and mosaic states cannot be assessed by this testing methodology.

Practical Information:

Sample required: 9ml EDTA -whole blood OR 5µg genomic DNA

Request / Payment / Consent Form:  The sample being  sent to the laboratory must be accompanied by a completed test request, payment and consent forms, which can be downloaded from our website.  There is currently no Medicare rebate for this test in Australia.

Turnaround time: 8-10 weeks

Further Information:

If you would like to find out more about cardiac gene panel testing or pricing please contact our Molecular Genetics department at Mater Pathology on 07) 3163 6017 or visit http://pathology.mater.org.au/cardiac.

References:

1. Kelly and Semsarian: Circulation: Cardiovascular Genetics.2009; 2: 182-190

2. Deo R, Albert CM. Epidemiology and genetics of sudden cardiac death. Circulation. 2012;125(4): 620-637

3. Guidelines for Genetic Testing of Inherited Cardiac Disorders: The Cardiac Society of Australia and New Zealand (2011).

4.  Ingles and Semsarian; Trends Cardiovasc Med. 2014 Aug; 24(6):217-24.