Personal genomic testing
At this time, the clinical utility of personal genomic testing, or online DNA testing, is considered variable and depends on the specific variants that are reported. If patients wish to pursue testing, ensure they opt for a full-service provider that includes the need for referral by a general practitioner (GP), test interpretation and genetic counselling support.
What is personal genomics?
With the advancement of gene sequencing technology, genetic testing is increasingly moving beyond the clinic and tertiary medical centres, and into the community. This new form of testing is readily accessible via the internet, either through a health practitioner or by individuals themselves, and represents the new world of personal genomic testing.
Clinical genetic testing has traditionally been used to gather information or confirm a diagnosis of a condition in an individual showing symptoms. Testing has also been used to screen asymptomatic populations, such as for recessive conditions. Until recently, these genetic tests have been targeted, looking for particular (or mutations) in specific genes. Clinical support, including genetic counselling, has generally been available to help individuals interpret and manage genetic test results.
However, new technology (eg [SNP] ) can now examine thousands of throughout a person’s
New sequencing technology also allows the entire sequencing of an individual genome (whole genome sequencing) at a relatively low cost. The availability of such technology is challenging the traditional model of genetic testing.
Asymptomatic individuals now have the opportunity to access ‘direct-to-consumer’ (DTC), ‘at-home’ testing, or ‘online DNA testing’, through a range of private providers.
Some DTC companies require a health practitioner to order a test on behalf of the consumer and take delivery of the test results, while others do not. A test kit provided by the DTC company is used to collect a cheek swab or saliva sample and mailed back for analysis. In some cases, results are returned to the consumer without comprehensive interpretation and/or clinical support.
While personal genomic testing has predominantly been offered as a direct-to-consumer service through international companies, in Australia clinicians can order certain types of personal genomic test for their patients through commercial laboratories. This includes panels for carrier screening for autosomal recessive conditions, pharmacogenomics and some polygenic risk scores (eg for certain cancers).
What do I need to know?
Personal genomic testing refers to the analysis of some or all of a person’s genome. Personal genomic testing is marketed for a variety of purposes, including:
- identification of susceptibility to a wide range of diseases using polygenic risk scores
- for autosomal recessive conditions
- nutrigenomics (ie diet, nutrition, wellness)
- fitness and sporting abilities
- relationship (eg paternity) testing
The cost of personal genomic testing varies according to the type of test (eg SNP , , , whole genome sequencing ) and how much information is provided with the results. Personal genomic testing is not funded by the Medicare Benefits Schedule (MBS), so consumers incur the full cost.
Personal genomic testing results may be provided with some clinical interpretation in the form of follow-up genetic counselling or a written report, or as raw sequence data. In some situations, the consumer is left to interpret the results without clinical guidance. This can prompt the individual to contact their GP for additional support. Referral of all such patients to public genetics services for assistance is not practicable given the resource implications.
What is tested?
Personal genomic testing can provide information that is health or non-health related. Non-health related information includes:
- physical traits (eg red hair, freckles)
- genetic relationship testing (eg paternity testing)
Some tests offer information that have health-related implications to varying degrees. In some cases, the tests are the same as those offered in regular clinical settings. Personal genomic tests might include genetic variants that:
- are associated with high risk for disease with greater certainty (eg BRCA1, familial breast and ovarian cancer)
- are associated with a wide range of disease risks with variable levels of evidence (eg polygenic risk scores for cancers, heart disease)
- are limited predictors of disease (eg APO-ε4, Alzheimer disease)
- identify carrier status for recessive conditions (eg cystic fibrosis)
- can inform response to drugs (refer to ‘Pharmacogenomics’ ).
Some companies test for variants for other health-related information that are more uncertain, such as variants with low , or with limited evidence to support associations with disease. These tests might include genetic variants that are:
- marketed to predict sporting ability, including fitness and response to training regimens
- professed to provide information about response to diet and nutrition (nutritional genomics) or weight loss (eg MTHFR gene testing). In Australia, these tests are advertised as ‘genomic wellness’ tests, and are increasingly available through naturopaths and nutritionists.
How do I manage personal genomic testing in general practice?
Advising patients who want personal genomic testing
Patients may ask a GP to order personal genomic testing on their behalf. GPs asked to arrange personal genomic testing should consider the following:
- How much does the patient understand about the test?
- What do they want to find out from the test and what will they do with that information?
- Has the patient thought about the possible impact of testing on life insurance? (Refer to ‘Ethical principles’)
- Will the company help interpret the results?
- Do you feel able to assist the patient in interpreting results?
Managing patients who have had personal genomic testing
Patients who have already had personal genomic testing might ask a GP for:
- help in interpreting the results
- further testing
- advice around treatment or management
The majority of patients will have small variations in risks for a range of conditions, which will have limited clinical implications. In these circumstances, general preventive health advice is appropriate.
In a minority of patients, specific variants that put an individual at significantly increased risk of a condition (eg BRCA gene mutations, HFE-haemochromatosis, macular degeneration) will be identified. In these situations, referral to genetics or specialist services is appropriate.
Implications for general practice
The uptake of personal genomic testing is likely to continue, and GPs will increasingly encounter patients who are curious about or have used personal genomic testing.
Commercial companies may begin to promote personal genomic testing to GPs, especially as the evidence builds for the clinical validity and utility of some components of these tests.
Some personal genomic testing companies recommend using specific practitioners (ie those they nominate who may have undertaken some training) who will order the test on behalf of the consumer. Some of these companies may also provide genetic counsellors who can discuss the results with the consumer.
Other companies state that the personal genomic testing reports are provided for information or educational purposes only. They may state that the consumer should talk to their GP or other health practitioners about their results. However, practitioners themselves may have a limited understanding of the nature of the test or its interpretation.
The National Health and Medical Research Council (NHMRC) has developed a personal genomic testing resource entitled ‘Understanding direct-to-consumer (DTC) genetic DNA testing: An information resource for consumers’. GPs can use this document to discuss personal genomic testing with patients who are interested in ordering a test.
- Reihm HL. Evolving health care through personal genomics. Nat Rev Genet. 2017. doi: 10.1038/nrg.2016.162.
- Direct-to-consumer genetic testing. Genetics Education Canada Knowledge Organisation.
- Torkamani A, Wineinger N, Topol EJ. The personal and clinical utility of polygenic risk scores. Nature Genetics Reviews 2018.
- ACMG Board of Directors. Direct-to-consumer genetic testing: A revised position statement of the American College of Medical Genetics and Genomics. Genet Med 2016;18(2):207.Savard J, Terrill B, Dunlop K, Samanek A, Metcalfe SA. Human Genetics Society of Australasia Position Statement: online DNA testing. Aug 2019.
- Savard, J Terrill B, Dunlop K, Samanek A and Metcalfe SA, on behalf of the Education, Ethics and Social Issues Committee of the Human Genetics Society of Australasia. Human Genetics Society of Australasia position statement: online DNA testing. Twin Res Hum Genet, 2020 Aug;23(4):256-258.