Cancer is not one disease. It's hundreds of diseases, each driven by a unique combination of genetic mutations, environmental exposures, and random biological events. Most cancers — 90–95% — arise from somatic mutations, meaning they develop during your lifetime in specific cells and aren't inherited. These cancers can't be predicted by genome testing.
But 5–10% of cancers are driven, at least in part, by inherited germline mutations — variants you were born with, present in every cell of your body, and detectable through whole genome sequencing. For individuals carrying these variants, early detection through genetic testing can be the difference between proactive screening and a late-stage diagnosis.
Beyond BRCA: The Hereditary Cancer Genes Most People Don't Know
BRCA1 and BRCA2 are by far the most well-known cancer susceptibility genes, largely due to Angelina Jolie's public disclosure in 2013 of her BRCA1 mutation and subsequent preventive surgery. But they're just two genes in a much larger landscape of hereditary cancer risk. Here are others that whole genome sequencing can detect:
TP53
Sometimes called the "guardian of the genome," TP53 normally suppresses tumor formation. Pathogenic variants dramatically increase lifetime risk for sarcomas, breast cancer, brain tumors, adrenocortical carcinoma, and leukemia — often at young ages. Lifetime cancer risk approaches 90–100%.
APC
APC mutations cause hundreds to thousands of polyps to develop in the colon, with near-certain progression to colorectal cancer without intervention. FAP accounts for about 1% of all colorectal cancers and typically manifests in adolescence.
MLH1 / MSH2
The most common hereditary colorectal cancer syndrome. Carriers face a 40–80% lifetime risk of colorectal cancer and a 20–60% risk of endometrial cancer, plus elevated risks for ovarian, gastric, and urinary tract cancers. Affects roughly 1 in 300 people.
CHEK2
Less dramatic than BRCA but far more common. CHEK2 variants approximately double breast cancer risk and moderately increase colorectal cancer risk. Because the risk increase is moderate rather than dramatic, CHEK2 is often missed by targeted panels that focus on high-penetrance genes.
PALB2
PALB2 works directly with BRCA2 in DNA repair. Pathogenic variants confer a breast cancer risk comparable to BRCA2 — roughly 33–58% lifetime risk depending on family history. Now recognized as a high-penetrance breast cancer gene worthy of the same clinical attention as BRCA.
RB1
Germline RB1 mutations cause retinoblastoma (childhood eye cancer) and elevate lifelong risk for osteosarcoma, soft tissue sarcomas, and melanoma. Early detection through genetic testing enables screening that can save both vision and life.
This is not an exhaustive list. Dozens of additional genes have established associations with hereditary cancer risk, including CDH1 (hereditary diffuse gastric cancer), BRIP1 (ovarian cancer), RAD51C and RAD51D (ovarian cancer), MUTYH (colorectal cancer), and many others. The ACMG (American College of Medical Genetics and Genomics) maintains an evolving list of genes recommended for secondary findings reporting in clinical genome sequencing.
What Genotyping Misses — and Why It Matters for Cancer
Consumer genotyping tests like 23andMe check for a small selection of known BRCA1/BRCA2 variants — specifically, three founder mutations common in Ashkenazi Jewish populations. This is dangerously incomplete for two reasons.
First, BRCA1 and BRCA2 have thousands of known pathogenic variants, not just three. If you carry a different BRCA mutation, a genotyping test will return a negative result, potentially giving false reassurance. This has happened to real people with devastating consequences — individuals who tested "negative" on 23andMe's limited panel, only to be diagnosed with BRCA-associated cancer later.
Second, many hereditary cancer genes (TP53, APC, MLH1, MSH2, PALB2, CHEK2, and others) aren't covered by consumer genotyping arrays at all, or are covered only by a handful of common variants. A comprehensive cancer risk assessment requires sequencing the complete coding and non-coding regions of these genes — which is exactly what whole genome sequencing provides.
What Genome Testing Can Tell You
Carrier status for known pathogenic variants. WGS can identify whether you carry established pathogenic or likely pathogenic mutations in cancer susceptibility genes. These classifications follow the ACMG/AMP five-tier framework: pathogenic, likely pathogenic, variant of uncertain significance (VUS), likely benign, and benign.
Variants of uncertain significance. WGS will also identify VUS — genetic variants that have been observed but don't yet have enough evidence to be classified as pathogenic or benign. These are the gray area of genetic testing, and their clinical interpretation requires professional expertise. A VUS today may be reclassified as pathogenic — or benign — as more research data accumulates. This is one reason why keeping your raw data for future re-analysis is so valuable.
Structural variants and copy-number changes. Some hereditary cancer syndromes involve large deletions, duplications, or rearrangements that genotyping arrays cannot detect. WGS can identify these structural changes across the entire genome.
What Genome Testing Cannot Tell You
Genetic testing cannot diagnose cancer. It identifies inherited risk factors, not active disease. A pathogenic BRCA1 variant means elevated risk, not a diagnosis. Many carriers never develop cancer. Many cancer patients carry no identifiable hereditary variants.
Genetic testing cannot capture somatic mutations — the mutations that arise during your lifetime and drive the majority of cancers. These are detected through tumor sequencing (sequencing the cancer itself after diagnosis), not germline sequencing (sequencing your inherited DNA).
Genetic testing cannot account for environmental and lifestyle factors. Tobacco use, UV exposure, diet, alcohol consumption, and dozens of other non-genetic factors contribute significantly to cancer risk. A "clean" genetic profile does not mean low cancer risk if environmental risk factors are present.
What to Do If You Find a Pathogenic Variant
If consumer WGS identifies a pathogenic or likely pathogenic variant in a cancer-associated gene, the single most important next step is a consultation with a certified genetic counselor or clinical geneticist. This is not optional and it is not replaceable by internet research.
A genetic counselor can contextualize the finding against your family history, recommend confirmatory clinical testing through a certified laboratory, outline appropriate screening protocols (such as enhanced MRI screening for BRCA carriers), discuss risk-reduction options, and coordinate with your medical team to implement a management plan.
Consumer WGS providers like Dante Labs deliver ACMG-classified results, which means their reports use the same pathogenicity framework that clinical laboratories use. However, consumer WGS is not a substitute for clinical genetic testing for medical decision-making. If an actionable variant is identified, clinical confirmation through an established genetic testing laboratory is the standard of care.
Comprehensive Cancer Gene Coverage
Dante Labs 30× WGS sequences every cancer susceptibility gene in full — BRCA1, BRCA2, TP53, APC, MLH1, MSH2, PALB2, CHEK2, and hundreds more.
Get 10% Off with Code GENOME → ACMG-classified variants · CLIA certified · From €169 on flash saleThe Bottom Line
Genome testing for cancer risk is a tool, not a crystal ball. It can identify inherited variants in cancer susceptibility genes with high accuracy and clinical relevance — but only when the results are interpreted by qualified professionals in the context of your complete medical and family history.
For individuals with a family history of cancer, particularly early-onset cancer or multiple affected relatives, comprehensive genetic testing through WGS or clinical gene panels is a reasonable and potentially life-saving step. For the general population without a strong family history, the value is less immediate but still real — roughly 1 in 300 people carry Lynch syndrome mutations, and most don't know it until a cancer diagnosis.
What genome testing offers is information. What you do with that information — the screening decisions, the lifestyle adjustments, the conversations with your medical team — is where the real impact happens. The genetics loads the gun. The environment pulls the trigger. Knowing what's loaded gives you the chance to respond before the trigger is pulled.