Stop assuming negative results mean zero risk when variants of uncertain significance require ongoing reclassification monitoring

A variant of uncertain significance (VUS) is a genetic test finding for which available evidence is insufficient to determine whether the change is benign or disease-causing. A negative result, meanwhile, generally means that the test did not identify a pathogenic or likely pathogenic variant within the genes and variant types examined—not that inherited risk is zero. The American College of Medical Genetics and Genomics (ACMG) and the Association for Molecular Pathology (AMP) state that a VUS should not guide medical decision-making, while the National Cancer Institute emphasizes that a negative hereditary-cancer test may still leave residual risk. Because scientific evidence changes, both negative results and VUS findings require appropriate interpretation, family-history assessment, and, when indicated, ongoing reclassification monitoring.

Requires ongoing monitoring: Variant of Uncertain Significance reclassification

Variant of Uncertain Significance reclassification monitoring is the continuing review of genetic findings as laboratories, researchers, and clinical databases obtain new evidence about a variant’s population frequency, biological effect, family segregation, functional impact, or relationship to disease. ACMG/AMP defines a VUS as a variant for which the available evidence is insufficient to classify it as benign, likely benign, pathogenic, or likely pathogenic.

The central safety principle is that a VUS is neither a confirmed diagnosis nor a confirmed explanation for disease. It should not, by itself, trigger preventive surgery, intensified screening, predictive testing of relatives, or changes to treatment. Instead, clinicians generally base care on the patient’s personal history, family history, established risk models, and any pathogenic or likely pathogenic findings reported in the test.

Germline VUS and somatic VUS

A germline VUS is an uncertain change present in inherited DNA and potentially shared by relatives. It may appear on hereditary-cancer, cardiovascular, neurological, or other constitutional genetic testing. A somatic VUS is an uncertain change detected in a tumor or other acquired cell population. In oncology, a somatic VUS generally does not provide sufficient evidence for selecting a targeted therapy, whereas a pathogenic or likely pathogenic alteration may have treatment implications.

These categories have different monitoring pathways. Germline reclassification may use family segregation and long-term population data; somatic interpretation may change as clinical trials, tumor databases, and treatment-response evidence develop. In both settings, the uncertainty label must be read in the context of the laboratory report, the test method, and the clinical question.

Benign, pathogenic, and likely classifications

The ACMG/AMP framework uses five principal categories: benign, likely benign, uncertain significance, likely pathogenic, and pathogenic. Reclassification usually moves a VUS toward a benign or likely benign interpretation, but some variants move toward likely pathogenic or pathogenic when stronger disease-related evidence emerges. A change in classification does not necessarily mean that the patient’s health status has changed; it means that the interpretation of the genetic evidence has changed.

In a study of approximately 1.45 million individuals published in JAMA, Mersch and colleagues reported that about 24.9% received at least one VUS and that 7.3% of VUS findings were later reclassified during the study period. Among reclassified findings, most were downgraded, but a clinically important minority were upgraded. These figures demonstrate why uncertainty should be managed as an evolving interpretation rather than treated as a permanent result.

Does not eliminate: Negative genetic test residual risk

A negative genetic test means that the laboratory did not identify a reportable pathogenic or likely pathogenic variant under the test’s design and analytical limits. It does not prove that no inherited predisposition exists. Residual risk can remain because the relevant gene was not included, the causal variant lies in a region or variant class that the assay cannot reliably detect, the disease is caused by a gene not yet known, or the family’s disease pattern is not explained by a single detectable variant.

True negative versus uninformative negative

A true negative is most informative when a pathogenic familial variant is already known and the tested relative does not carry that specific variant. In that circumstance, the person may be able to avoid increased surveillance associated with the familial condition, subject to professional interpretation.

An uninformative negative occurs when testing finds no pathogenic variant but no confirmed familial variant was available for comparison. This result may reduce the likelihood of some known genetic causes, but it does not eliminate inherited or familial risk. The National Cancer Institute and the Centers for Disease Control and Prevention advise that personal and family history can continue to justify genetic counseling, risk assessment, or enhanced screening after a negative result.

Technical and knowledge limitations

Test sensitivity varies by platform. Sequencing may detect many single-nucleotide changes and small insertions or deletions but may require additional methods to identify some copy-number changes, repeat expansions, structural variants, deep intronic changes, or mosaic findings. A panel can also be negative because the causal gene was not included or because the scientific community has not yet linked the relevant gene or variant to disease.

Interpretation is also influenced by the diversity of reference data. The Genome Aggregation Database has improved population-frequency analysis, but genetic databases remain unevenly representative of global populations. A variant that is rare in one reference group may be more common in another, affecting the confidence of benign or pathogenic classifications. This limitation is one reason that a negative result should be interpreted alongside ancestry, phenotype, and family structure rather than in isolation.

Should be reviewed: VUS reclassification monitoring practices

Reclassification monitoring is the process of checking whether a laboratory has issued an amended report or whether authoritative databases have updated a variant’s interpretation. Many laboratories maintain internal review programs and may notify the ordering clinician when a clinically meaningful classification changes, but notification policies and time frames vary. Patients should not assume that every laboratory automatically contacts them indefinitely, especially after a change in clinician, health system, insurance coverage, or contact information.

What laboratories and clinicians should do

• Document the laboratory, test date, gene, variant notation, classification, and report version.
• Confirm how the laboratory handles amended reports and whether updated contact information is on file.
• Reassess the result when personal or family history changes, when a new diagnosis occurs, or when a relative receives a more informative genetic result.
• Use expert resources such as ClinVar, ClinGen, and gene-specific evidence groups, while recognizing that database entries may differ in quality and purpose.
• Refer unresolved findings to a certified genetic counselor or genetics professional rather than interpreting a VUS independently.

What patients and families should do

Patients should retain the complete laboratory report, not only a summary stating “negative” or “uncertain.” They can ask the ordering clinician or laboratory whether the result is eligible for periodic reinterpretation and how updates will be communicated. A reasonable review interval depends on the disorder, the laboratory, and the strength of the family history; periodic contact with a genetics professional is more reliable than assuming that a result will update automatically.

Relatives should generally not undergo predictive testing solely for a VUS, because the result usually cannot establish whether they inherited disease risk. Testing an affected relative may sometimes be more informative, particularly when the family has a strong pattern of disease and no pathogenic variant has yet been identified. Any such strategy should be designed by a genetics professional.

Illustrates risk: Familial cancer testing after a negative result

Consider a person with several close relatives diagnosed with breast or colorectal cancer who receives a multigene panel reported as negative, or a panel that identifies only a VUS. That result does not automatically reduce the person’s screening needs to average-population levels. The family pattern may reflect an undetected variant, a gene not included on the panel, a combination of lower-risk variants, shared environmental factors, or chance. Management should therefore be based on validated risk assessment and the family history while the VUS remains non-actionable.

A useful visual for patient education would be a two-track flowchart: one track showing “pathogenic familial variant not detected” as a potentially informative true negative, and another showing “no familial variant known” as an uninformative negative requiring continued risk assessment. A second timeline could show how a VUS moves from uncertain to likely benign or likely pathogenic as population, laboratory, family, and functional evidence accumulates.

Conclusion: Reclassification monitoring protects against false reassurance

Variant of Uncertain Significance reclassification monitoring recognizes that genetic interpretation is dynamic. Germline and somatic VUS findings are not diagnoses, and ACMG/AMP guidance says they should not independently direct medical decisions. A negative test is also not synonymous with zero risk: a true negative can be reassuring when a known familial variant is absent, while an uninformative negative may leave substantial residual risk.

The most responsible approach combines accurate classification, documented laboratory follow-up, periodic reinterpretation, and clinical management based on personal and family history. Patients should preserve their reports, confirm the laboratory’s update policy, and consult a genetic counselor or qualified clinician when risk remains unclear. Continued reading from ACMG, ClinGen, the National Cancer Institute, and the Centers for Disease Control and Prevention can help patients and professionals distinguish a negative finding from a guarantee of no inherited risk.

Sources: Richards S, Aziz N, Bale S, et al., “Standards and Guidelines for the Interpretation of Sequence Variants,” Genetics in Medicine, https://www.nature.com/articles/gim201530; Mersch J, Brown N, Pirzadeh-Miller S, et al., “Prevalence of Variants of Uncertain Significance in Multigene Panel Testing for Hereditary Cancer,” JAMA, https://jamanetwork.com/journals/jama/fullarticle/2685556; ClinGen, Variant Classification and Evidence Frameworks, https://clinicalgenome.org/working-groups/variant-curation/; National Cancer Institute, Genetic Testing Fact Sheet, https://www.cancer.gov/about-cancer/causes-prevention/genetics/genetic-testing-fact-sheet; Centers for Disease Control and Prevention, Genetic Testing for Hereditary Cancer Syndromes, https://www.cdc.gov/genomics/disease/hereditary_cancer/index.htm; Genome Aggregation Database, Population Genetic Variation Resource, https://gnomad.broadinstitute.org/