Genetic Test Selection and Interpretation
Genetic test selection and interpretation is the area of genetic counseling concerned with deciding when a genetic test is appropriate, choosing among available test types, and translating the laboratory result into a clinically meaningful statement. It connects the clinical question that motivated testing to the molecular evidence a laboratory can return, and to the uncertainty that often accompanies that evidence.
Definition
Genetic test selection and interpretation refers to the linked processes of choosing a genetic test suited to a clinical question and applying standardized evidence frameworks to classify and report the resulting variants, including their certainty and clinical implications.
Scope
The area orients the reader to the full path of a genetic test: the indications that justify ordering it, the analytic and clinical performance of different testing strategies, the standardized framework used to classify sequence variants from benign to pathogenic, the special problem of variants of uncertain significance, population-level and carrier screening, and the management of results found incidentally rather than sought. It treats these as methodological and interpretive topics, not as a protocol for individual patient management.
Sub-topics
Core questions
- When is a genetic test indicated, and what clinical question is it meant to answer?
- How are different testing strategies (single-gene, panel, exome, genome) chosen for a given indication?
- How is the pathogenicity of a sequence variant classified from available evidence?
- How should uncertainty in classification and incidental findings be handled and communicated?
Key concepts
- Test indication and clinical utility
- Analytic versus clinical validity
- Variant classification (benign to pathogenic)
- Variant of uncertain significance
- Carrier and population screening
- Secondary and incidental findings
- Pre- and post-test counseling
Mechanisms
A genetic test begins with a clinical question that determines which strategy is appropriate, ranging from targeted single-variant assays to panels, exome, and genome sequencing, each with different detection scope and cost (Schwarze et al., 2018). The laboratory then identifies variants and classifies them against a standardized evidence framework that weighs population frequency, computational predictions, functional data, and segregation to place each variant on a benign-to-pathogenic scale (Richards et al., 2015). Interpretation also depends on the clinical context: the same variant may carry different implications depending on phenotype, family history, and the reason for testing. Pharmacogenomic testing illustrates how genotype is linked to a downstream clinical consequence through known gene-drug relationships (Wang et al., 2011).
Clinical relevance
Understanding how genetic tests are selected and interpreted is central to appraising genetic evidence and to genetic counseling practice. The area describes how results are generated and classified and how their certainty is communicated; it is a reference orientation for understanding the testing pathway and not a basis for ordering tests or making individual diagnostic or treatment decisions.
Epidemiology
The clinical use of genetic and genomic testing has expanded substantially as sequencing costs have fallen, broadening from single-gene tests for specific disorders to exome and genome sequencing across many indications; cost-effectiveness evidence for the broader approaches remains heterogeneous (Schwarze et al., 2018).
History
Genetic testing grew from cytogenetic and biochemical assays toward DNA-based and, later, high-throughput sequencing methods. As the volume and breadth of detected variants increased, the field developed shared frameworks for classifying variant pathogenicity, consolidated in the 2015 ACMG/AMP consensus recommendation, which standardized how laboratories weigh evidence and report results (Richards et al., 2015).
Debates
- How broad should first-line testing be?
- Whether to begin with targeted tests or with exome/genome sequencing involves trade-offs in diagnostic yield, cost, and the burden of uncertain or incidental findings, and the cost-effectiveness evidence base is still developing.
Key figures
- Sue Richards
- Heidi Rehm
- Sean Tavtigian
Related topics
Seminal works
- richards-2015
- schwarze-2018
Frequently asked questions
- What does this area cover?
- It covers how a genetic test is chosen for a clinical question and how the laboratory result is classified, reported, and understood in terms of certainty and clinical meaning.
- Is broader sequencing always better than a targeted test?
- Not necessarily; broader strategies such as exome or genome sequencing increase scope but also raise cost and the chance of uncertain or incidental findings, so the appropriate choice depends on the clinical question.