# Compare a genetic panel’s scope before counting its genes

*Draft • Research checked 4 October 2026 • AI-assisted DomDNA editorial content. No independent clinical review or publication is claimed. General education, not individual medical advice.*

Two laboratories advertise genetic panels for a similar question, but one lists more genes. Before treating the longer list as the better answer, compare the test’s purpose, the changes it can detect and the regions its analysis includes. A gene count leaves several technical questions unanswered.

Your reader question is: “Which parts of this test produced a valid result, and what remained outside its scope?” This also helps you preserve the difference between a negative finding and a no-call, where the laboratory could not make a valid call.

## Match the test to the question

[MedlinePlus describes different genetic-test types](https://medlineplus.gov/genetics/understanding/testing/types/), including targeted variants, individual genes, panels and broader sequencing. Clinicians choose among them according to the question. The word “panel” does not establish identical content or methods across services.

Consider two invented panels. Panel A analyses 20 genes and includes a validated method for detecting a specified class of deletions. Panel B analyses 80 genes, but its stated method excludes that class. For a question involving those deletions, the gene totals alone cannot tell you which test provides the needed information.

These fictional panels do not rank real laboratories or recommend a test. They show why you need the methods and limits beside the gene list. Ask the ordering team which changes it needs to investigate and whether the proposed assay can detect them.

## Read the performance description

The [Genetic Testing Registry’s submission guidance](https://www.ncbi.nlm.nih.gov/gtr/docs/submit/test_submission/) separates test targets, methodology and performance. It asks laboratories for analytical-validity information and assay limitations. These fields give you useful terms for a question; a registry entry does not itself verify a personal finding.

Write down the test name and version, then ask for the relevant regions and variant types. If the report mentions coverage limits, keep them with the result. Ask whether an excluded region is a design choice or a measurement problem. The testing team can explain what each means for the original clinical question.

Avoid translating “sequenced” into “fully assessed for all conditions”. A provider may measure information without analysing or reporting every possible finding. Its report needs to describe the analysis it performed.

## Keep a no-call visible

In its [GenCall technical note](https://support.illumina.com/content/dam/illumina-marketing/documents/products/technotes/technote_gencall_data_analysis_software.pdf), Illumina defines a no-call as failure to make a valid genotype call at a particular site. We use that definition for this specific genotyping context. Laboratories and formats may use different missing-result codes, so consult the test’s own documentation.

Imagine an invented table with three rows. One says “outside panel”. Another says “no valid call”. The third says “assessed; specified variant not detected”. The first describes scope, the second missing measurement, and the third a result within a defined assay. Combining them under one reassuring label would erase the distinction.

A missing result does not establish which DNA letters are present. Nor does it explain why the laboratory could not call that position. Ask whether the gap affects the intended interpretation and whether the laboratory recommends any further step. Do not replace the gap with a result from a different online tool.

## Compare the report’s boundaries

The [FDA’s consumer-test guidance](https://www.fda.gov/medical-devices/in-vitro-diagnostics/direct-consumer-tests) notes that companies may test different sets of variants. A negative consumer result does not remove all disease risk. That warning concerns consumer testing; a clinician can explain the different scope of a diagnostic panel.

For a side-by-side comparison, copy the purpose, targets and limitations from each service’s technical description. Add a row for how the laboratory handles failed or missing calls. Leave unknown information marked as unknown until the provider answers.

Keep each service’s reply with the version you compared. A later panel with the same marketing name may need its own technical description. Date your comparison so another reader can identify the documents behind it.

Your next step is to request a scope-and-limitations statement for the panel you are considering, including its missing-result policy. [DomDNA’s educational quiz](https://domdna.com/quiz) covers general lifestyle topics. It does not select genetic panels, repair no-calls or provide clinical test interpretation.