Genetic testing broadly falls into five categories. Single gene testing looks at one specific gene linked to a known condition. Gene panel testing examines a curated group of genes associated with a disease category. Chromosome testing detects larger structural or numerical abnormalities. Exome sequencing analyses the protein-coding regions of the genome. Genome sequencing analyses nearly the entire genome. Each serves a different clinical purpose, and choosing the right one depends on the specific clinical question being asked.
Genetic testing has moved from a specialised research tool into routine clinical practice. Pediatricians, oncologists, obstetricians, and several other specialties now order genetic tests regularly. Yet the range of test types available, and when each one is actually appropriate, remains unclear to many doctors outside dedicated genetics training.
This guide breaks down the main types of genetic testing, explains where each fits clinically, and looks at which medical specialties rely on this knowledge most.
What Is a Gene, and What Is DNA?
DNA is the molecule that carries the instructions for how the body develops and functions. A gene is a specific segment of DNA that codes for a particular protein or trait. Humans have roughly 20,000 genes, packaged into 23 pairs of chromosomes. When a gene carries an alteration, it may or may not affect health, depending on which gene is involved and what the alteration does.
Understanding whether a condition is inherited matters clinically. Some genetic conditions pass directly from parent to child in predictable patterns. Others result from a new, spontaneous change that isn't present in either parent. This distinction shapes both the testing approach and the conversation a doctor has with a patient's family.
Types of Genetic Testing Explained
Different clinical situations call for different testing approaches. Here's how the main types compare.
Examines one specific gene already suspected based on clinical presentation or family history. Used when a specific condition, such as a known hereditary disorder, is strongly suspected.
Examines a curated group of genes linked to a category of conditions, such as hereditary cancer or epilepsy. Useful when several genes could plausibly explain the same clinical picture.
Looks at the structure and number of chromosomes to detect larger abnormalities, such as an extra or missing chromosome. Commonly used in prenatal and developmental evaluation.
Analyses the protein-coding portion of the genome, roughly 1-2% of total DNA, which contains the majority of currently known disease-causing variants. A broader net than a gene panel.
Genome sequencing goes further still, analysing nearly the entire genome, including regions that don't code for proteins. It's the most comprehensive option, generally reserved for cases where more targeted testing hasn't provided an answer, given its higher cost and complexity of interpretation.
Broader isn't automatically better. A single gene test is often faster, cheaper, and easier to interpret than exome or genome sequencing when the clinical picture already points strongly to one condition. Test selection should follow the clinical question, not default to the most comprehensive option available.
The Role of Genetic Counselling
Genetic testing and genetic counselling are related but distinct. Testing generates a result — and the main types of genetic testing include diagnostic testing, predictive testing, carrier testing, and prenatal testing, each serving a different clinical purpose. Counselling helps a patient or family understand what a result actually means, including its implications for other family members and future pregnancies. Genetic counselling typically happens both before testing, to set expectations and confirm informed consent, and after testing, to interpret results and discuss next steps.
Which Medical Specialties Rely on Genetic Testing Most?
Clinical genetics isn't confined to a single specialty. Several fields depend on it regularly, each for different reasons.
| Specialty | Why Genetic Testing Matters Here |
|---|---|
| Pediatrics | Diagnosing congenital and developmental conditions, often shortly after birth |
| Obstetrics & Gynaecology | Prenatal screening and diagnosis during pregnancy |
| Oncology | Identifying hereditary cancer risk and guiding targeted, genomically informed treatment |
| Neurology | Diagnosing inherited conditions affecting the brain, spinal cord, and nervous system |
| Cardiology | Evaluating inherited heart conditions, including certain cardiomyopathies and arrhythmias |
| Hematology | Diagnosing inherited blood disorders and certain clotting conditions |
In each of these fields, a doctor doesn't need to become a geneticist to benefit from this knowledge. Recognising when a genetic cause should be considered, and which type of test fits the clinical question, is often the more immediately useful skill.
Reading and Interpreting Genetic Test Reports
A genetic test report typically classifies findings using standard categories: pathogenic, likely pathogenic, variant of uncertain significance, likely benign, or benign. The "variant of uncertain significance" category is a common source of confusion. It means a genetic change was found, but current evidence isn't sufficient to say whether it causes disease. This requires careful, honest communication with patients rather than an oversimplified reading of the result.
Family history assessment and pedigree analysis often complement the test report itself, helping place a genetic finding in proper clinical context rather than interpreting it in isolation.
Frequently Asked Questions
What is a pedigree in genetics?▼
What's the difference between clinical genetics and genetic counselling?▼
Recognising when genetic testing is indicated, choosing the right test, and interpreting results confidently takes structured training. MGA's Fellowship in Clinical Genetics helps eligible doctors build this expertise across genetic disorders, family history assessment, testing, and counselling.
Explore Fellowship in Clinical GeneticsThis article provides general educational information on genetic testing categories and their clinical use as of September 2026. It is not a substitute for individualised clinical or genetic counselling assessment. Specific test selection and interpretation should be guided by a qualified clinical geneticist or genetic counsellor based on individual patient and family circumstances.