Genetic and genomic testing both involve looking at a person’s DNA. While genetic testing looks at one or several specific genes, genomic testing looks at an individual’s whole genome (their full set of genes) to identify alterations in DNA which might affect their health.
Some DNA alterations – sometimes called ‘pathogenic genetic variants’ or ‘genetic mutations’ – can cause certain genes not to work, or to work differently. There are thousands of medical conditions that are expressions of particular genomic alterations.
A genetic or genomic test will usually be ordered by your GP or specialist clinician. It involves having samples of your blood, saliva, or tissue taken and sent to a Genomic Laboratory Hub, where some or all of your genome is then analysed.
Test results may take days, weeks, or sometimes months to be finalised, depending on what the test is for. If your doctor thinks genetic or genomic testing may be appropriate for you, you may also be referred for genetic counselling.
Why have a genomic test?
There are a number of reasons why a genetic or genomic test may be suggested to you:
Testing may be performed to help your clinician decide how to treat your condition, or to prescribe medicine that will be most effective for you, with the least side effects. See our page about drug response testing.
If your family has a known history of a genetic condition, such as hereditary cancer
syndromes, or certain heart conditions like long QT syndrome or hypertrophic
cardiomyopathy, predictive or ‘pre-symptomatic’ testing may be offered to assess your risks
of developing the condition, and guiding preventative care.
This may be available to multiple members of your family if there is a risk of passing specific
genetic conditions onto children. Examples of cases where carrier testing is performed
include cystic fibrosis or thalassaemia.
Tests may be used to diagnose genetic conditions in your unborn baby. These might include
Down’s syndrome, or other conditions known to affect your family. See our page on prenatal and newborn testing.
Other reasons for genomic testing:
Genomic testing can be helpful in a wide range of medical scenarios, including in
transplantation, the diagnosis of infectious diseases, and preimplantation genetic diagnosis
Genomic testing enables personalised healthcare
Personalised, or ‘precision’ medicine is a move away from a ‘one size fits all’ approach to the
treatment and care of people with a particular condition. Genomic testing opens up new
approaches for healthcare professionals to treat and manage patient conditions with a
greater focus on individual needs and predispositions.
How do I participate in genomic testing?
There are many NHS clinics across the East of England that support the delivery of genomic
and genetic testing. See our care pages for more details.
- NHS England on personalised medicine
- NHS Choices: an overview of genetic medicine
- Your questions answered: Genetics and inheritance
- Your questions answered: Confidentiality and ethics
- Genomics commentary from Professor Sue Hill, Chief Scientific Officer and Senior Responsible Officer for Genomics in NHS England