Loeys-Dietz Syndrome — an aggressive connective tissue disorder where aortic dissection occurs at smaller diameters and younger ages than in Marfan syndrome, making genotype the key to setting the right surgical threshold.
Whole genome sequencing evaluates TGFBR1, TGFBR2, SMAD3, TGFB2, and TGFB3 simultaneously, distinguishing Loeys-Dietz from Marfan syndrome and vascular Ehlers-Danlos — a distinction that directly determines aortic surgical intervention timing.
Loeys-Dietz Syndrome
Loeys-Dietz syndrome (LDS) is an autosomal dominant connective tissue disorder caused by pathogenic variants in genes encoding components of the transforming growth factor-beta (TGF-β) signaling pathway. LDS is genetically heterogeneous, with five recognized subtypes: LDS type 1 (TGFBR1), type 2 (TGFBR2), type 3 (SMAD3), type 4 (TGFB2), and type 5 (TGFB3). LDS was first described in 2005 and is characterized by a triad of features: arterial tortuosity and widespread aneurysm formation, hypertelorism (widely spaced eyes), and bifid or broad uvula or cleft palate. The cardiovascular features are the primary source of morbidity and mortality.
The critical clinical distinction between Loeys-Dietz syndrome and phenotypically similar conditions — particularly Marfan syndrome and vascular Ehlers-Danlos syndrome — lies in the aggressiveness of aortic disease. LDS patients experience aortic dissection at significantly smaller aortic root diameters than Marfan patients. While prophylactic aortic root replacement in Marfan syndrome is typically recommended at 5.0 cm, LDS guidelines recommend surgical intervention at 4.0-4.2 cm for aortic root diameter in LDS type 1 and 2. Additionally, LDS produces aneurysms throughout the arterial tree — not limited to the aortic root — requiring whole-body vascular imaging surveillance that is not standard in Marfan management.
Distinguishing LDS from Marfan syndrome requires molecular confirmation because the phenotypes overlap substantially: both can present with aortic root aneurysm, skeletal features (pectus deformity, scoliosis, joint hypermobility), and dural ectasia. A patient with LDS misclassified as Marfan syndrome would have their surgical intervention threshold set 1 cm above their actual safe limit — a difference that can be the boundary between prophylactic repair and emergency dissection. Genetic testing is therefore not ancillary to clinical diagnosis in this population — it is the primary determinant of surgical timing and surveillance strategy.
Five LDS subtypes have been defined based on the causative gene. TGFBR1 and TGFBR2 variants produce the most aggressive vascular phenotype; SMAD3, TGFB2, and TGFB3 variants tend toward milder disease with later onset but require equivalent vascular surveillance.
Marfan panels test FBN1. LDS panels add TGFBR1/2. Neither approach captures all five LDS genes, the full connective tissue differential, and the intronic variants that explain genotype-negative familial aortic disease.
The differential between LDS, Marfan, and vascular EDS determines surgical management — not just diagnosis
Aortic root aneurysm in a young patient with connective tissue features triggers a differential that includes Marfan syndrome (FBN1), Loeys-Dietz syndrome (TGFBR1/TGFBR2/SMAD3/TGFB2/TGFB3), vascular Ehlers-Danlos syndrome (COL3A1), familial thoracic aortic aneurysm (ACTA2, MYH11), and others. Each diagnosis carries a different surgical threshold, different surveillance protocol, and different recommendations for activity restriction and pregnancy management. Sequential single-gene or limited-panel testing introduces delays — every month between clinical suspicion and molecular confirmation is a month during which the aortic root may be enlarging past the unrecognized true safe threshold. Whole genome sequencing evaluates all of these genes simultaneously in a single test.
De novo LDS variants are common — a negative family history does not exclude the diagnosis
Approximately 25-30% of LDS cases arise from de novo variants with no family history of aortic disease or connective tissue disorders. This means the first presentation of LDS in a family may be an acute aortic dissection in a young patient whose prior evaluation found 'no family history' and in whom a clinical-only assessment may not have triggered genetic testing. Having a complete genome result — including the TGF-β pathway genes — in the medical record before an acute vascular event provides the information needed for rapid clinical decision-making if an adverse vascular event occurs.
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.
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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 Loeys-Dietz 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.
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One test.
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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
