Medical technology3 min read
Genome sequencing and genetic testing
WGS
A genetic test looks for changes in genes, chromosomes or proteins; more than 77,000 genetic tests are in use. Whole genome sequencing reads the order of every DNA “letter” and is increasingly used in healthcare and research.
Both whole-exome and whole-genome sequencing rely on modern technologies that read large amounts of DNA quickly. According to NHGRI, some large medical centres have begun using sequencing to detect and treat some diseases, and doctors can increasingly use sequencing data to identify a patient's type of cancer.
Sequencing sometimes reveals variants whose meaning is not yet known, or variants linked to another undiagnosed genetic disorder (incidental or secondary findings); so what will be reported is discussed before the test. An NHGRI page (2023) notes that routine sequencing in the doctor's office is still years away.
- In widespread clinical use
- Approved for specific uses
- In clinical trials
- Preclinical
- Concept
Genetic tests are widely used, whereas whole-genome sequencing is used in specific cases and centres and its use is increasing; it has not yet become a routine test in the clinic.
- Targeted genetic testsIn widespread clinical use
More than 77,000 genetic tests are currently in use.1
- Whole-genome or whole-exome sequencingApproved for specific uses
Its use is growing in care and research, and some large centres have begun using it to detect and treat some diseases.23
- Identifying cancer type from sequencing dataApproved for specific uses
Doctors can increasingly use sequencing data to identify the type of cancer.3
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What is it?
A genetic test is a type of medical test that identifies changes in genes, chromosomes or proteins.
Whole-genome sequencing determines the order of all the nucleotides in a person's DNA, and exome sequencing reads the parts that carry the instructions for making proteins.
How does it work?
Both methods rely on new technologies that allow large amounts of DNA to be read quickly.
Where is it used today?
Genetic medicine has already had an impact in fields including oncology and pharmacology, and genetic markers are increasingly being added to cancer tests.
Doctors increasingly use sequencing data to identify the type of cancer, which is the basis of precision medicine.
Limits and risks
Much of the information that sequencing reveals is not yet known to have any meaning.
Sequencing may reveal a variant linked to another genetic disorder not yet diagnosed, which are called incidental or secondary findings.
According to NHGRI (2023), routine sequencing in the doctor's office is still years away.
Common questions
Can genetic testing reveal something I wasn't looking for?
Yes, sequencing may reveal a variant linked to another undiagnosed disorder, which are incidental or secondary findings; it is best to discuss this with the doctor or genetic counsellor before the test.2
Questions for your doctor
- What exactly will this genetic test look for, and what will it not detect?
- How will incidental findings be reported if they appear?
References
- 1MedlinePlus Genetics (NLM). What is genetic testing?. medlineplus.gov/genetics/understanding/testing/genetictesting/Health agencies & guidelines · Accessed 2026-10-08
- 2MedlinePlus Genetics (NLM). What are whole exome sequencing and whole genome sequencing?. medlineplus.gov/genetics/understanding/testing/sequencing/Health agencies & guidelines · Accessed 2026-10-08
- 3NHGRI (NIH). DNA Sequencing Fact Sheet. www.genome.gov/about-genomics/fact-sheets/DNA-Sequencing-Fact-SheetHealth agencies & guidelines · Accessed 2026-10-08
- 4NHGRI (NIH). Genomics and Medicine. www.genome.gov/health/Genomics-and-MedicineHealth agencies & guidelines · Accessed 2026-10-08
Review status: Edited content · Last updated:
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Educational content only — no diagnosis, and no substitute for a clinician.