A genomic test is a complex process that takes time and involves several specialists. Here, we break it down for you.
Step 1: The right test
The first step is to determine if genomic testing is right for you. Genetic and genomic testing can help provide a definitive diagnosis for many people with a health condition. For some, it can inform treatment or management. For others, it may not be relevant.
Your doctor or another medical specialist will first determine if genomic testing is appropriate for your condition. There are a range of genetic and genomic tests. The right test for you depends on the type of gene or gene change (variant) being looked for.
Step 2: Informed consent
You need to agree to the test. Genomic testing can provide uncertain or unexpected results and can have implications for other family members. Gaining your informed consent is a crucial step before the test.
Your medical specialist, genetic counsellor or oncologist will provide support for you to make an informed decision during this stage, whether it’s proceeding or declining the test.
Step 3: Sample collection
It’s time to get your DNA. Genomic testing is done by collecting a blood, saliva or tissue sample. This sample is sent to the laboratory where a medical scientist extracts the genetic material – your DNA.
Step 4: Sequencing
Now, experts identify your unique genetic code. A medical scientist will use very sophisticated machines to sequence your DNA. Sequencing determines the order of the four ‘letters’ in your genetic code (A, C, T, G), which is unique to you. Depending on the type of test, sequencing will target a specific group of genes, the exome (the protein-coding areas of the genome) or your entire genome.
Step 5: Analysis
Next, experts look for differences. Your DNA sequence data is analysed firstly by a computer using a pipeline – a series of algorithms and statistical steps to check quality, assemble your DNA sequence and compare your DNA against a reference genome, and provide a list of variants that could be relevant to your condition.
A bioinformatician develops and maintains these pipelines. The reference genome used is a sequence compiled from many human genome sequences and is sourced from an international data base.
By comparing your DNA to a reference, a medical scientist can sort through which variants (gene changes) may explain your condition. Not all variants cause disability or a health condition. Every person has lots of variants – they are what makes each of us unique!
|Analysing genomic data for cancer|
At the analysis step when testing for cancer, experts will look for genes associated with cancer. A medical scientist will sort through which variants may 'drive' (cause) your cancer to find a more definitive diagnosis.
This enables clinicians to understand what the cancer may do, such as the symptoms and overall outlook for your health.
Step 6: Variant interpretation
The detective work begins here. An expert team that can include medical scientists, pathologists and clinical geneticists prioritise the variants found based on how likely they are to explain your condition or the cause of your cancer. Information about these variants is examined closely in a process known as ‘curation’.
For inherited conditions, the curated variants are then classified on a scale based on the significance of the change to your condition: benign variants are not the cause of a condition, while pathogenic variants are considered to be the cause of the condition.
For cancer, when the test reveals ‘driver’ variants, experts will scan the available evidence to see if there are effective treatment options for these variants that can help guide your care and improve outcomes.
Step 7: Case review
Experts review the evidence to reach a verdict. Once the list of variants is narrowed, your detective team gets bigger to include clinical geneticists, genetic counsellors, medical scientists and sometimes your referring doctor.
The multi-disciplinary team of experts looks at all the available information, including your condition and history, to determine if any of the variants are relevant to your condition. For example, has the same gene variant been found in other people with a similar condition?
Once a decision is made, a report will be prepared for your referring doctor. Sometimes the team suggest further scientific testing to decide whether the variant is causing the condition or not.
Step 8: Interpret and provide results
Experts explain what has been found. The report can be complex, so your referring doctor – sometimes accompanied with a genomics specialist – will interpret this report and discuss it with you. The results might indicate potential changes to your treatment plan or cancer therapy.
Step 9: Post-test counselling
Your team discusses what the result means. Genomic test results may have significant implications for you and your family.
Your doctor or a genetic counsellor can answer any questions you may have to ensure you understand all aspects of the test results, how the results may change your care, or the care of other family members. They can also talk through the options if nothing is found through your genomic test, and help you find further support.
Frequently asked questions
- Who can order a genomic test?
- What conditions can genomic tests be used for?
- How much does genomic testing cost?
- What happens to my genomic information after testing?
Who can order a genomic test?
Your medical specialist or clinical geneticist will be able to tell you if genomic sequencing will be helpful for your condition. If appropriate, a specialist or a clinical geneticist can order a genomic test from a specialised laboratory with the equipment and expertise to do a genomic test.
What conditions can genomic tests be used for?
Genomic testing can be used for a range of genetic conditions that affect all body systems. It can be helpful for some complex conditions in children. It can also detect the cause of cancer and help in cancer care. Genomic testing can also help to track outbreaks of infectious disease.
How much does genomic testing costs?
In Australia, Medicare or state funded genomic testing is available for some conditions. Your genetics service or medical specialist can advise whether funded testing is available.
What happens to my genomic information after testing?
Your genomic data is stored by the pathology provider who performs the genomic test. Your consent, as well as federal and state privacy laws govern the use of this data.