Next-Generation Sequencing

Next-generation sequencing, or NGS, is a laboratory method for reading many DNA regions in parallel. A sample may come from blood, saliva, a tumour or cells collected for a reproductive test. The laboratory compares the detected sequence with a reference and reports changes that fit the test design. The result is not a complete description of every feature of your health or every genetic change in the sample.

The panel or sequence is selected to answer a defined clinical question. In oncology, genomic tumour profiling may identify changes that the treating team can consider with pathology, scans and your medical history. In inherited-risk care, a panel can examine several genes associated with a family pattern. NGS is also used in carrier screening, reproductive testing and some prenatal tests, each with its own sample, scope and result categories.

NGS only examines the regions and types of changes included in the laboratory method. A result may be positive, negative, uncertain or unable to provide a clear answer. A tumour result may reflect cancer cells rather than an inherited change, while a blood result may not describe every change inside a tumour. Confirmation with another method, a focused test, pathology, imaging or genetic counselling may be appropriate.

The meaning of an NGS result depends on why testing was ordered, which sample was used and how the laboratory classified the finding. A reportable change may guide a conversation; it does not automatically determine a diagnosis or treatment. An uncertain finding should not be treated as proof of disease. Ask whether the result is inherited or tumour-specific, whether relatives might need advice, and what follow-up is recommended.

The physical part of testing is often sample collection, but results can have emotional and family implications. Before testing, ask what the panel covers, whether unexpected findings may be reported, how the sample and data are handled, and who will explain the result. Share relevant family history and tell the clinician if you are pregnant or considering fertility treatment, because the purpose and interpretation of testing can change.