Genetic Testing: Types, Benefits, and What to Expect
Genetic testing has moved from the realm of specialised medical clinics into everyday life, with consumer DNA kits sold in pharmacies and medical tests capable of detecting disease risk before symptoms ever appear. But the growing availability of genetic testing has also created confusion about what different tests actually measure, what positive and negative results mean, and how to make sense of information that is often complex and probabilistic rather than clear-cut. Understanding the landscape before you test is the best way to make testing genuinely useful.
Types of Genetic Tests
Genetic tests serve fundamentally different purposes and analyse the genome at different levels of resolution. Carrier testing determines whether you carry one copy of a recessive disease allele — relevant if you are planning a family and want to know whether your children could inherit a condition like cystic fibrosis or sickle cell disease. Diagnostic testing confirms or rules out a suspected genetic condition in someone already showing symptoms. Predictive and presymptomatic testing assesses risk for conditions that may develop in the future, such as hereditary breast and ovarian cancer or hereditary haemochromatosis. Prenatal and preimplantation testing screens embryos or foetuses for chromosomal abnormalities or specific genetic conditions before or during pregnancy. Consumer ancestry and health tests from companies like 23andMe or AncestryDNA provide a much less comprehensive analysis focused on ancestry, ancestry-associated traits, and selected health predispositions.
What Tests Can and Cannot Tell You
A critical limitation of genetic testing is that most common diseases are not caused by single gene variants — they are influenced by many genetic and environmental factors. A positive result for a disease-associated variant does not mean you will develop the disease; it indicates elevated probability. A negative result does not eliminate risk entirely. The predictive value of a result depends heavily on what specifically was tested, the penetrance of any variant found, your personal and family medical history, and the current state of scientific knowledge about that variant's clinical significance.
The Role of Genetic Counselling
Genetic counsellors are healthcare professionals trained to help individuals and families understand genetic information in the context of their specific circumstances. Before testing for heritable disease risk, a counsellor helps you understand what a test can measure, what results might mean for you and your relatives, and how to think through the decision. After testing, counsellors help interpret results, discuss implications for family members who may also be at risk, and connect you with appropriate medical specialists. For any test with potential clinical significance, engaging a genetic counsellor before and after testing is strongly recommended.
Privacy and Ethical Considerations
Genetic information is uniquely personal and permanent — unlike a blood pressure reading, you cannot change your DNA sequence. The Genetic Information Nondiscrimination Act (GINA) in the United States prohibits health insurers and employers from discriminating based on genetic information, but protections are incomplete, and life and disability insurance remain unregulated in this area. Before testing, especially with consumer genomics companies, understand their data sharing practices, how they handle security, and whether your data may be used for research or sold to third parties.
Browse educational resources about genetic testing on our genetics platform, or contact us to learn more about responsible approaches to genetic testing and counselling.