A genomic sequencing test aims to identify changes (variants) in any of the large number of genes in your genome that may affect your health.
Genomic sequencing tests - whole exome sequencing
Patients involved in the Melbourne Genomics clinical projects have had different types of genomic sequencing tests performed, depending on their condition.
Most patients have had a test called whole exome sequencing.
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.
Some of Melbourne Genomics' clinical projects performed gene panel tests. These involve looking for changes in a specific list of genes. An example is a comprehensive cancer panel which may include 300 to 400 different genes.
There are other types of genomic tests, such as whole genome sequencing, where the whole genetic code (not just the exons) is sequenced.
You can download our infographic, which explains more about genomic tests.
How are genomic tests performed?
How are samples for the test collected?
A DNA sample is required for a genomic sequencing 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 members Victorian Clinical Genetic Services (VCGS) the Australian Genome Research Facility and Peter MacCallum Cancer Centre Molecular Pathology laboratory.)
How are gene changes or variants identified?
Computer programs are used to analyse genomic data. The computer scans this data for differences (variants) between the sequence of the person being tested and a reference sequence.
This list of variants is filtered further using computing methods, then examined to see if any identified variant might have an impact on health or might explain a person's medical condition.
The first step is to establish whether a variant or change in a gene will stop it working properly. To do this, a scientist considers 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 our Community resources section.
Could I have a genomic test?
Genomic tests are not yet routinely available in everyday healthcare in Victoria. Doctors can usually only access genomic sequencing through Victoria's Genetics Services or research studies, which are generally limited to patients with particular conditions.
More information about genetic and genomic testing in Victoria is available here.
If you would like to learn more about genomic testing for cancer treatment, your oncologist should be able to provide you with further information.
Melbourne Genomics is investigating the best way to offer genomic testing in everyday healthcare, and is generating evidence to show which patients will benefit.
Member organisations of the Melbourne Genomics Health Alliance are gaining experience in the use of this technology, and almost 4,000 patients at Alliance member hospitals who fit specific criteria have been able to access genomic sequencing through our program.
Read more about the work of Melbourne Genomics.
If you are a participant in one of our programs, please see the For patients section.