A saliva tube on your kitchen table and a blood draw at a genetics clinic can both produce a report mentioning a gene like BRCA1. That surface similarity hides large differences in how many variants are examined, how the laboratory is regulated, how the result is confirmed, and — most importantly — what a clinician can responsibly do with it. This explainer walks through what actually differs between direct-to-consumer (DTC) genetic testing and clinical (diagnostic) genetic testing, using published figures so you can read either kind of report with realistic expectations.
What each type of test is designed to do
DTC tests are sold straight to the public, usually for ancestry and general-interest traits, with some health reports bundled in. Clinical genetic tests are ordered by a clinician for a medical question — for example, assessing inherited cancer risk in someone with a strong family history. The design goals are different, and that shapes everything downstream.
The clearest illustration is the BRCA health report many people recognise. When the FDA authorised 23andMe’s BRCA report in 2018, it covered just three founder variants common in people of Ashkenazi Jewish descent: 185delAG and 5382insC in BRCA1, and 6174delT in BRCA2. A clinical hereditary-cancer panel, by contrast, sequences the full coding regions of BRCA1, BRCA2 and often dozens of other genes.
Coverage: three variants versus the whole gene
This is the difference that catches most people out. There are more than 1,000 known pathogenic variants across BRCA1 and BRCA2. A three-variant DTC report can only ever find those three. A 2023 retrospective cohort study in JCO Precision Oncology quantified the gap: limiting analysis to the Ashkenazi founder variants missed more than 90% of pathogenic or likely-pathogenic BRCA1/BRCA2 variants in people of non-Ashkenazi ancestry, and about 10% even within the Ashkenazi group. A “normal” DTC BRCA result is therefore not the same as a negative clinical test — it simply means those specific variants were absent.
Accuracy and the false-positive problem
DTC genotyping arrays are optimised for breadth, not diagnostic certainty. When DTC raw data or third-party interpretation tools flag a variant, that flag is frequently wrong. A 2018 Genetics in Medicine study found that 40% of variants reported in DTC raw data were false positives on clinical confirmation; several flagged as “increased risk” were actually benign common variants. The JCO cohort similarly reported a high false-positive rate for non-founder BRCA calls. This is why a positive DTC result should be treated as a prompt to confirm, never as a diagnosis.
Regulation and laboratory standards
Clinical genetic tests are run in laboratories certified under the Clinical Laboratory Improvement Amendments (CLIA) and often accredited by the College of American Pathologists (CAP), with documented analytic validity. Many DTC services are not held to those diagnostic standards. Clinical reports also classify each variant on the five-tier ACMG/AMP scale — pathogenic, likely pathogenic, variant of uncertain significance (VUS), likely benign, benign — so the clinical weight of a finding is explicit. DTC health reports rarely provide that nuance.
Side-by-side
| Feature | Direct-to-consumer | Clinical / diagnostic |
|---|---|---|
| Ordered by | The consumer | A clinician |
| BRCA coverage (typical) | 3 founder variants | Full BRCA1/BRCA2 sequencing + panel |
| Method | Genotyping array (selected spots) | Next-generation sequencing + del/dup analysis |
| Lab standard | Often not CLIA/CAP diagnostic-grade | CLIA-certified, frequently CAP-accredited |
| Variant classification | Limited or absent | 5-tier ACMG/AMP |
| Result usability | Confirm before acting | Actionable, counselled |
Secondary findings — a clinical concept with no DTC equivalent
When a clinical exome or genome is sequenced, the lab may report medically actionable “secondary findings” unrelated to the original reason for testing. The list is standardised: ACMG SF v3.2 (2023) recommends reporting 81 genes spanning cancer, cardiovascular, and metabolic conditions, with CALM1, CALM2 and CALM3 among the additions. This structured, opt-in framework — counselling included — has no real counterpart in consumer kits.
The heritage behind careful reporting
The value of disciplined, clinically confirmed reporting is exactly what hereditary-cancer registries such as PROMPT helped establish, contributing to the ASCO/JCO evidence base on how inherited variants should be interpreted and acted upon. That history is a reminder that a gene name on a page is only the beginning of the work.
The bottom line
DTC and clinical genetic tests are not two grades of the same product. A DTC kit screens a handful of pre-selected spots and is best treated as a conversation-starter; a clinical test sequences the relevant genes in an accredited lab, classifies each variant, and comes with counselling and confirmation. A reassuring DTC result does not rule inherited risk out, and a worrying one needs clinical confirmation before any decision. If inherited risk is a real question for you or your family, a clinical pathway is the one designed to answer it.
Educational explainer, not medical advice. For your own testing or results, speak with a clinician or genetic counsellor.