Your son's mind works differently, learns differently — and you've been searching for the explanation. It's written in a repeated sequence of three letters.
Fragile X testing via whole genome sequencing identifies full mutations, premutation carriers, and transmission risk — enabling early intervention, family screening, and access to emerging therapies.
Fragile X Syndrome
Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability and the most common single-gene cause of autism spectrum disorder. Prevalence is approximately 1 in 4,000 males and 1 in 8,000 females. FXS is caused by a CGG trinucleotide repeat expansion in the 5' untranslated region of the FMR1 gene. Normal alleles have 5–44 repeats; premutation alleles have 55–200 repeats; full mutation alleles have more than 200 repeats, which triggers hypermethylation and gene silencing. Inheritance is X-linked, meaning affected males are typically more severely symptomatic (intellectual disability, behavioral issues, characteristic facial features, macroorchidism) while affected females have more variable and milder phenotypes due to random X-inactivation.
Premutation carriers are at risk for distinct conditions: fragile X-associated tremor/ataxia syndrome (FXTAS) — progressive neurodegeneration primarily affecting older males — and fragile X-associated primary ovarian insufficiency (FXPOI), occurring in approximately 20% of female premutation carriers and affecting fertility. The CGG repeat exhibits unstable inheritance: premutation alleles (55–200 repeats) undergo expansion during maternal meiosis and can expand to full mutation in a single generation. Maternal repeat length correlates with expansion risk: mothers carrying higher repeat counts have higher probability of transmitting a full mutation to offspring.
A confirmed FMR1 full mutation diagnosis enables early intervention services (speech, occupational, behavioral therapy from infancy), targeted pharmacotherapy for associated anxiety and ADHD, and educational planning informed by intellectual disability severity. It enables cascade testing of female relatives — identifying premutation carriers at risk for FXTAS (progressive neurodegeneration) and FXPOI (premature menopause affecting fertility planning). Preconception carrier screening for FMR1 premutation is now recommended by ACOG for all women considering pregnancy. Genetic counseling guides prenatal diagnosis options and family planning decisions.
Fragile X has two distinct clinical presentations: full mutation (FXS with intellectual disability) and premutation carriers (who may develop FXTAS or FXPOI without FXS).
Standard short-read sequencing cannot detect CGG repeat expansions. Fragile X is systematically missed unless specifically tested.
Standard Genome Test cannot detect CGG trinucleotide repeats — Fragile X is invisible on most genetic tests
Standard short-read exome and genome sequencing universally FAIL at detecting CGG repeat expansions in FMR1. The repetitive nature of the region causes sequencing reads to fail or collapse, making the repeat invisible to standard bioinformatic pipelines. Fragile X testing has historically required specialized molecular methods: PCR-based repeat sizing followed by Southern blot analysis for methylation status. This means Fragile X is systematically missed by standard next-generation sequencing panels and even many 'comprehensive' genetic tests unless Fragile X-specific testing is explicitly ordered. Long-read sequencing technologies (PacBio, Oxford Nanopore) now enable repeat expansion detection from Genome Test data, but this requires specialized analytical pipelines and Dante Labs must confirm their capability.
Early testing identifies full mutation cases and premutation carriers — enabling prevention of transmission
A confirmed FMR1 full mutation diagnosis guides early intervention services (speech, occupational, behavioral therapy from infancy), enabling optimal neurodevelopmental outcomes with early support. Carrier testing of female relatives identifies premutation carriers who are at risk for FXTAS (progressive neurodegeneration), FXPOI (premature menopause and fertility planning), and transmission of full mutation to offspring. Preconception carrier screening is now ACOG-recommended for all women considering pregnancy. Prenatal diagnosis via CVS or amniocentesis is available for at-risk pregnancies. Genetic diagnosis connects families to the robust Fragile X research community and emerging therapies including gene therapy approaches in development.
Your full DNA (not just a part of it)
Traditional genetic testing looks at narrow sets of genes, missing most parts of your genome. We sequence your full genome — every gene and every region between genes.
Comprehensive insights and specialized reports
Easy to read and with answers you and your doctor can act on. Not a file to interpret — 200+ clinical reports, organized by category.
Your test becomes more valuable every year
Your DNA does not change, but genome science is accelerating. Every month, new variant-disease associations are discovered. We validate these findings and update your reports automatically. Your test becomes more valuable every year.
The results doctors bring to their hardest cases.
Forty years of uncertainty. One test.
A patient had spent decades in the UK healthcare system without a diagnosis. Dante data, accepted by NHS clinical teams at Queen Elizabeth University Hospital Glasgow, identified Noonan Syndrome and a RUNX1 leukemia-associated variant that had gone undetected. After 40 years, they finally had an answer.
A complete read delivers a complete picture.
A patient came to Dante to investigate periodic paralysis. Reading the complete genome identified a concurrent hereditary cardiac finding — Brugada syndrome — that their doctor confirmed with an ECG. The result also explained a family member's unresolved cardiac history. One test. Every answer in it.
Sequenced in 2019. The data worked in 2021.
Jennifer sequenced her genome with Dante two years before her breast cancer diagnosis. When treatment began, Dante's pharmacogenomics data showed her prescribed chemotherapy would cause serious adverse effects. Her doctor selected an alternative — and she started effective treatment from day one.
Every genetic question deserves a complete answer.
Whether you are searching for answers today or protecting your health for tomorrow, a complete read of your entire genome is the only place to start.
It runs in your family. Now you can know if it runs in your genes.
Your genome contains inherited variants associated with medical conditions like cardiac, cancer, and neurological. We read all of them — with the clinical depth to give the result meaning.
Learn more →When traditional lab tests say you're fine. And you know you're not.
Standard diagnostic tests check for a pre-selected set of answers. We sequence your full DNA — including parts that no test was designed to check. If the answer is in your genome, we will help you find it.
Learn more →Your diagnosis may be right. Your treatment plan may be incomplete.
Your genes determine which treatments are most likely to work — and which are not. We give your doctor the tools and insights to inform your treatment plan.
Learn more →You want to know before something forces the question.
Some people don't wait for a diagnosis or a family history to act. Whole genome sequencing gives you the complete genetic picture now — so you and your doctor can make informed decisions before anything becomes urgent.
Learn more →You already took a DNA test. Here's what it couldn't tell you.
Most consumer DNA tests read less than 0.1% of your genome. We read all of it.
Learn more →Clinical-grade results. Chosen by individuals, trusted by doctors for their most complex cases.
Dante Genome Test helped specialists at a UK national acute hospital in the identification of Noonan Syndrome and a rare leukemia-associated genetic variant that had gone undetected. That result changed the medical care of the patient.
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Common questions about whole genome sequencing.
What is the difference between whole genome sequencing and a targeted genetic test?
Targeted genetic tests — including standard hereditary cancer panels — read a pre-defined list of known variants in a specific set of genes. They are designed to find what they already know to look for. Whole genome sequencing reads your entire genome: all 6 billion base pairs, every gene, every region between genes. A Mayo Clinic study published in JAMA Oncology found that standard testing guidelines missed more than half of patients with inherited cancer mutations. Genome Test does not have a fixed list.
What will I receive when my results are ready?
Your Dante Genome delivers 200+ physician-ready reports organized by clinical category — hereditary cancer, cardiac conditions, rare diseases, pharmacogenomics, carrier status, and more. Reports are delivered to your secure Genome Manager and are formatted for direct clinical use. Your genome data is permanently retained and re-analyzed automatically as science advances.
What happens if a clinically significant variant is found?
If a pathogenic or likely-pathogenic variant is identified, it will be clearly flagged in your physician-ready report with clinical context, published evidence, and recommended next steps. We recommend sharing any clinically significant finding with your physician or a genetic counselor, who can guide decisions about surveillance, risk reduction, or cascade testing for family members.
How is this different from a consumer DNA test like 23andMe or AncestryDNA?
Consumer DNA tests use genotyping chips that read less than 0.1% of your genome — a tiny pre-selected set of common variants. They are optimized for ancestry and population-level traits, not clinical genetic findings. The Dante Genome Test sequences 100% of your genome at 30X coverage, the same standard used in clinical diagnostic settings. The two tests are not comparable in scope, methodology, or clinical utility.
How long does it take to get results, and how are they delivered?
Your collection kit ships within 48 hours of ordering. Once your sample arrives at our CLIA-certified laboratory, sequencing and analysis takes 6–8 weeks. Results are delivered securely to your Genome Manager, where you can access your reports, share them with your physician, and receive automatic updates as new findings are validated against your genome.
We work with patient advocacy groups worldwide.
Dante Labs works with patient advocacy groups of any size — for Fragile X Syndrome and other conditions, rare and common. We support groups in any country, including virtual patient advocacy groups.
We can provide customized reports, group discounts, and packages tailored for your members. Please reach out using the form and we'll be in touch within two business days.
- Custom genomic reports for your members
- Group discounts and tailored packages
- Any country — including virtual groups
- Rare and common conditions covered
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We’ll be in touch within 2 business days. To follow up directly: hello@dantelabs.com
One test.
A lifetime of answers.
One kit, sent to your home. Your entire genome sequenced at the clinical standard used for diagnostic decisions. 200+ physician-ready reports delivered to your Genome Manager in 6–8 weeks — permanent and updated as science advances.
Ships within 48 hours · Results in 6–8 weeks
