A genomic sequencing test aims to identify changes, or ‘variants’ in any of the large number of genes in your genome that may affect your health.
Genomic sequencing tests - About whole exome sequencing
Melbourne Genomics provided genomic sequencing tests called 'whole exome sequencing' to patients involved in our clinical projects.
We each have about 23,000 genes in our entire genome. Your exome is only about one per cent of your genome – but this is the part most important for health.
A whole exome sequencing test aims to identify changes (variants) in your exome that may help diagnose or treat your medical condition.
How are genomic tests performed?
How are samples for the test collected?
A DNA sample is required for a genomic test. DNA can be obtained from a number of body tissues, but the most common way is from a blood sample. The sample is sent to a pathology laboratory where the DNA can be ‘extracted’ or taken from the sample.
What is genomic sequencing?
Genomic sequencing is a process where DNA is examined and the DNA code is ‘written out’ into a letter code and saved in a computer file as genomic data. The sequencing is done by laboratories that specialise in genomic sequencing (for instance, Alliance partners Victorian Clinical Genetic Services (VCGS) , the Australian Genome Research Facility and The University of Melbourne Centre for Translational Pathology.)
How are gene changes or variants identified?
Computer programs are used to analyse genomic data. The computer scans this data for differences or ‘variants’ between the sequence of the person being tested and sequences from other people.
This list of variants is then examined to see if any might have an impact on health or might explain a condition someone might have.
The first step is to establish whether a variant or change in a gene will stop it working properly. To do this, a specialist examines each variant using large databases or scientific papers.
Then a team of experts, including medical laboratory scientists, bioinformaticians (computer specialists who deal with biological data), doctors and geneticists, match the list of variants which may impair gene function against a person’s health and family medical history. This is how they determine if a particular variant is likely to be the underlying cause of a genetic disease. Or, in other cases, whether a variant might affect how a person might respond to particular treatments.
For more on genomic testing, see the For participants section.
Could I have a genomic test?
At present, genomic tests are still being developed and are not yet routinely available in everyday healthcare in Victoria. Doctors can usually only access genomic sequencing through research studies, and these studies are generally limited to a small number of conditions. This means that relatively few patients can access genomic sequencing through clinical genetic services in Australia. It can be difficult to access such testing even if doctors think it might be useful. Talk to your GP or healthcare provider if you have any questions about genomic testing.
Melbourne Genomics is working to determine the best way to offer genomic tests in everyday healthcare. Member organisations of the Melbourne Genomics Health Alliance have some experience in the use of these technologies, and patients at Alliance member hospitals who fit specific criteria are having genomic sequencing.
Read more about the work of Melbourne Genomics.
If you are a participant in one of our programs, please see the For participants section.