Marfan Syndrome and FBN1 Genetic Testing: What Research Says About Inheritance and Aortic Risk

Marfan Syndrome and FBN1 Genetic Testing: What Research Says About Inheritance and Aortic Risk

This article is for educational purposes only. It does not replace diagnosis, treatment or genetic counseling. It is not a substitute for advice from a licensed physician, board-certified medical geneticist, or board-certified genetic counselor. For any decisions about testing, treatment, or care, consult a qualified clinician. In emergencies, call 911.

Bottom line: Research shows that an FBN1 gene change is not, by itself, a Marfan diagnosis. In a large US study, 58 of every 100 people with a disease-causing FBN1 variant had no Marfan diagnosis in their health records. The real danger is a tear in the body’s main artery. Regular scans, blood pressure drugs and planned surgery lower that danger. Many people with Marfan now have a normal lifespan.

What you’ll learn

• How Marfan passes through families, and why a gene result alone is not a diagnosis
• What registries and trials say about aortic risk, in plain “out of 100 people” terms
• How clinical gene panels differ from consumer tests such as 23andMe
• What the 2022 ACC/AHA guideline says about scans, drugs, surgery, pregnancy and family testing

How Marfan syndrome is inherited: FBN1, fibrillin-1 and one altered copy

Marfan syndrome is a condition of the body’s connective tissue. Connective tissue is the material that holds organs, joints and blood vessels together. Marfan affects about 1 in 5,000 people worldwide. That is about 2 in every 10,000 people.

The cause is a change in a gene called FBN1. FBN1 holds the recipe for fibrillin-1. Fibrillin-1 is a protein that helps build stretchy fibers in tissue. Think of it as the elastic thread woven through a sweater. When the thread is weak, the fabric stretches out of shape over time.

Marfan follows autosomal dominant inheritance. That means one altered copy of FBN1, from either parent, is enough to cause the condition. The key facts are below.

• Each child of an affected parent has a 50% chance of inheriting the variant. That is 50 out of 100 per pregnancy.
• About 75 of every 100 people with Marfan have an affected parent.
• About 25 of every 100 have a brand-new (de novo) variant, with no family history.
• The same variant can look very different in two relatives. Signs vary in severity, timing and speed.

Some other conditions look like Marfan but come from different genes. Examples include Loeys-Dietz syndrome, vascular Ehlers-Danlos syndrome and familial thoracic aortic aneurysm and dissection. This is one reason doctors often order a panel of several genes. Genetic counseling helps here. It is a visit with a trained expert who explains gene tests and family risk. A genetic counselor can say which genes make sense for a family.

Section recap: Marfan comes from one altered FBN1 gene. Each child of an affected parent has a 50 in 100 chance of inheriting it, but severity varies a lot.

How doctors diagnose Marfan: the revised Ghent criteria

Doctors diagnose Marfan mainly by looking at the body, not just the genes. They use a set of rules called the revised Ghent nosology, published in 2010. These rules put the most weight on two “cardinal” features.

• Aortic root enlargement. The aorta is the large artery that carries blood from the heart. The aortic root is the first part, right where it leaves the heart. In Marfan, it can widen and form an aneurysm (a bulge).
• Ectopia lentis. This means the lens inside the eye has slipped out of place.

To judge the aortic root, doctors use a z-score. A z-score compares a measurement with the average for people of the same body size. A z-score of 0 is average. A z-score of 2 or more means clearly larger than expected.

The table below sums up the main rules in plain terms.

Situation	What is enough for a diagnosis
No family history	Aortic root aneurysm plus ectopia lentis
No family history, only one of the two cardinal features	A true FBN1 variant or a mix of body features is needed
Person with a known Marfan FBN1 variant	Root z-score of 2.0 or more, or ectopia lentis
Relative in a well-defined Marfan family	Familial variant, ectopia lentis, systemic score of 7 or more, or root enlargement
Root enlargement cutoff for relatives	z-score 2.0 or more at age 20 and up, 3.0 or more under age 20

The “systemic score” adds up other body features. Common ones are listed below.

• Tall, slender build and arms that span wider than height
• Long, thin fingers (arachnodactyly) and loose joints
• A sunken or jutting chest bone, or a curved spine
• A collapsed lung that happens on its own
• Widening of the sac around the spinal cord (dural ectasia)
• Nearsightedness, which affects most people with Marfan

More than half of people with Marfan are nearsighted, and about 60 in 100 have a slipped lens. Mitral valve prolapse, a floppy heart valve, is also common. Signs can show up at any age, from infancy to adulthood.

Testing usually includes three steps. An echocardiogram is an ultrasound picture of the heart and aortic root. A slit-lamp eye exam checks the lens with a special microscope. CT or MRI scans can show the whole aorta, including parts that ultrasound cannot see.

The panel noted that a Marfan label can affect careers and life insurance. Careful rules help prevent a wrong or early label. Ask a cardiologist or clinical geneticist which of these exams a family needs.

Section recap: Marfan is diagnosed from the aortic root, the eyes and other body features, with gene results as one piece. The rules aim to avoid both missed and false diagnoses.

How likely is serious aortic disease? Registry data in plain numbers

The biggest danger in Marfan is aortic dissection. A dissection is a tear in the inner layer of the aorta. Blood then pushes between the layers of the wall. It can be life threatening.

Emergency warning: Sudden, severe pain in the chest, back or belly may be an aortic dissection. Call 911 right away. Do not wait to see if it passes.

Doctors split dissections into two main types. Type A starts in the ascending aorta near the heart. Type B starts further down, in the descending aorta that runs through the chest and belly.

Before reading the numbers, a few terms help.

• Carrier here means a person who has an FBN1 variant, with or without signs.
• Penetrance is the share of people with a variant who actually develop the condition.
• Relative risk (RR) compares how often something happens in one group versus another. An RR of 2 means twice as often. It does not tell anyone’s own chance. An odds ratio is a close cousin that compares odds instead.
• Absolute risk is the plain chance, such as “14 out of 100 people.”

Here is what recent studies found.

Study	What it measured	Result in plain numbers
All of Us (Felker 2026)	Share of FBN1 carriers with no Marfan diagnosis in health records	58 out of 100
Cornell registry (Narula 2023)	Type B dissection in 336 people with Marfan	47 people, about 14 out of 100
Cornell registry (Narula 2023)	Type A dissection in the same group	About 9 out of 100
Cornell registry, those with earlier scans	Descending aorta under 4.0 cm before type B dissection	88 out of 100
Korukonda meta-analysis (2025)	One variant group compared with another	RR 2.62 (likely range 1.90 to 3.61)

The All of Us result needs care. The 58% is not a penetrance figure. It only shows who lacked a Marfan diagnosis in electronic health records. It does not prove those people had healthy aortas. Still, the undiagnosed carriers had milder features than diagnosed carriers. The authors argue that studying only clinic families can make the condition look more severe than it is.

The Cornell registry shows a different side. In that one center, type B dissection was more common than type A. Most people who had a type B dissection already knew they had Marfan, 41 of 47.

Many had earlier root surgery, 79% versus 46% in those without type B. In 55 of 100 type B cases, the tear came a mean of 13.3 years after root surgery. The 2022 ACC/AHA guideline also notes that type B dissection is the first aortic event in about 10% of patients. This is why scans of the whole aorta matter for life, even after the root is fixed.

The Korukonda review pooled data from 11 studies and more than 6,000 adults. FBN1 variants come in types.

“Haploinsufficiency” variants mean the body makes too little fibrillin-1. “Dominant-negative” variants mean the body makes a faulty fibrillin-1 that disrupts the normal copy. People with haploinsufficiency variants had an aortic presentation 2.62 times as often as those with dominant-negative variants. That is a comparison between variant groups. It is not a personal risk figure, and it cannot be turned into “X out of 100” for one person.

Think of it like weather maps. A map can show which region gets more storms. It cannot say whether rain will fall on one house tomorrow. A cardiologist and genetic counselor can explain what these studies mean for a specific family.

Section recap: Many people with an FBN1 variant have no diagnosis, and registry numbers come from clinic patients. Type B tears can happen at normal aortic sizes, so lifelong whole-aorta scans matter.

Genetic testing options in the US and Canada: clinical panels vs consumer kits

There are two very different ways to look at FBN1. One is a clinical test ordered by a doctor or genetic counselor. The other is a consumer test bought directly by the public.

Feature	Clinical diagnostic panel	23andMe Premium Ancestry + Total Health	Genotyping kits (e.g., 23andMe Premium Ancestry + Health, AncestryDNA)
Who orders it	Physician or genetic counselor	A third-party clinician reviews and orders it	The consumer
How it reads DNA	Sequencing of FBN1 and related genes	Exome sequencing	Checks a few chosen spots only
Reports Marfan (FBN1)?	Yes	Yes, listed in the exome list	Not on the 23andMe genotyping list
Reports uncertain results (VUS)?	Usually, with counselor review	No, only pathogenic or likely pathogenic	Not applicable
Lab standard	CLIA lab recommended	CLIA- and CAP-accredited lab	Varies

In the US, clinical panels are often covered by insurance when signs or family history point to Marfan. In Canada, testing usually runs through provincial genetics clinics. Wait times and access vary by province.

Three points matter most for families.

• A standard genotyping kit should not be read as ruling Marfan in or out.
• A “not detected” result does not change standard screening. Relatives of a person with Marfan still need the exams their doctors advise.
• A positive consumer result should be checked in a clinical-grade lab. ACMG strongly recommends clinical gene tests be done in a CLIA-approved lab.

A useful analogy is a smoke detector versus a fire inspection. A consumer kit may sound an alarm. Only a full inspection, meaning clinical testing and heart scans, tells what is going on. Bring any consumer report to a primary care doctor or genetic counselor.

Section recap: Only 23andMe’s exome-based Total Health service lists Marfan, and standard kits cannot rule it out. Any positive consumer result needs clinical confirmation.

Reading the result: pathogenic, likely pathogenic, VUS and negative

Labs sort gene changes into five groups. These come from a 2015 standard by ACMG and AMP. Labs weigh several kinds of data, such as population, computer, lab and family data.

Result	Plain meaning	What usually comes next
Pathogenic	Strong evidence it causes disease	Heart scans, counseling, family testing
Likely pathogenic	Good evidence it causes disease	Handled much like pathogenic
Variant of uncertain significance (VUS)	Not enough evidence either way	Should not drive surgery or family decisions
Likely benign	Probably harmless	Usually no change
Benign	Harmless	No change

A VUS is a gene change that science cannot yet call harmful or harmless. Many are later reclassified as more data comes in. So a VUS is best seen as “unknown for now.”

A pathogenic FBN1 variant plus an enlarged aortic root meets the diagnosis rules. A pathogenic variant with a normal aorta and normal eyes is different. It calls for regular checks, not an automatic label. The All of Us data support this careful approach.

Specialists may also look at variant type, such as haploinsufficiency versus dominant-negative. The Korukonda authors propose tailoring scan timing and surgery by variant type. That is the authors’ proposal, not a guideline rule. It is still emerging evidence.

A negative result means different things in different situations. If a relative’s familial variant is known and a person tests negative for it, that is usually reassuring. If no variant has been found in the family, a negative test does not rule out Marfan.

A genetic counselor is the best guide here. In the US, counselors are certified by the American Board of Genetic Counseling (ABGC). In Canada, they are certified by the Canadian Board of Genetic Counselling (CBGC). The National Society of Genetic Counselors (NSGC.org) is a professional society, and it does not certify counselors.

Section recap: Pathogenic and likely pathogenic results guide care, while a VUS should not. Variant type is an emerging factor for specialists, not a personal forecast.

Surveillance, medication and preventive surgery: what the trials and the 2022 ACC/AHA guideline say

Care for Marfan rests on three pillars. These are regular scans, blood pressure drugs and well-timed surgery. All three are decisions for a cardiologist with aortic experience.

Regular scans

The 2022 ACC/AHA guideline sets this scan schedule.

When	Recommended imaging
At diagnosis	Echocardiogram (TTE), then again 6 months later to check growth
If stable	Echocardiogram once a year
If the aorta is not seen well	CT or MRI
Adults, after the first echo	CT or MRI of the chest aorta is reasonable
After root replacement	MRI or CT of the chest aorta yearly, then every other year if stable for 2 years
Belly aorta	Imaging every 3 to 5 years is reasonable

GeneReviews adds that echocardiograms may be needed more often in some cases. Examples are a root over about 4.5 cm in adults or fast growth. Think of these scans like checking tire tread. Regular checks catch wear before a blowout.

Medication

The guideline recommends a beta blocker or an angiotensin receptor blocker (ARB) at the highest dose a person tolerates. The goal is to slow aortic widening. This carries the guideline’s strongest grade, Class 1 with Level A evidence. Using both drug types together is called reasonable.

Two major studies shaped this advice.

Study	Who	Main finding
Pediatric Heart Network trial (Lacro 2014)	608 children and young adults, 6 months to 25 years	Atenolol and losartan slowed root growth similarly, with no significant difference
Marfan Treatment Trialists (Pitcher 2022)	1,442 people in 7 trials, no prior aortic surgery	ARBs roughly halved yearly root growth compared with no ARB
Pitcher 2022, ARB vs beta blocker	766 people in 3 trials	Results were similar

In the Lacro trial, root size fell relative to body size with either drug. Rates of surgery, dissection and death over 3 years did not differ between the groups. The trial also tracked adverse events as a secondary outcome. Note that its participants were young, not middle-aged adults.

In the Pitcher analysis, the ARB benefit did not appear to depend on beta-blocker use. The effect was especially large in people with pathogenic FBN1 variants. Beta blockers also did better than no treatment in an indirect comparison. So ARBs and beta blockers look similar, and neither has been shown to be better. The analysis was partly funded by the Marfan Foundation.

Regulatory status

No drug is approved specifically for Marfan in the US or Canada. Losartan, irbesartan and atenolol are approved for high blood pressure and other uses. None of their current labels mentions Marfan. So use for Marfan is off-label in both countries, even though the guideline recommends it.

Drug	FDA original approval	FDA-labeled uses	Health Canada status
Losartan (Cozaar), an ARB	1995-04-14	High blood pressure, stroke risk with a thick heart wall, diabetic kidney disease	Marketed, no Marfan use listed
Irbesartan (Avapro), an ARB	1997-09-30	High blood pressure, diabetic kidney disease	Marketed, no Marfan use listed
Atenolol (Tenormin), a beta blocker	1981-08-19	High blood pressure, angina, heart attack	Marketed for high blood pressure and angina

ARBs carry an FDA boxed warning for harm to an unborn baby. Health Canada has a matching serious warning. They must be stopped as soon as pregnancy is found.

Preventive surgery

Surgery replaces the widened aortic root before it can tear. Some operations keep the person’s own valve, called valve-sparing root replacement. The guideline thresholds for Marfan are below, with every condition kept.

Finding	Guideline position
Aortic root 5.0 cm or more	Replacement of root and ascending aorta is recommended (Class 1)
Root 4.5 cm or more plus a high-risk feature	Reasonable if done by experienced surgeons in a Multidisciplinary Aortic Team (Class 2a)
High-risk features for the line above	Family history of dissection, growth of 0.3 cm or more per year, wide root and ascending aorta, or very twisty arteries in the neck (vertebral arteries)
Root area divided by height of 10 or more (cm²/m)	Reasonable, with the same surgeon and team condition (Class 2a)
Near the threshold, valve-sparing candidate, very low surgical risk	May be reasonable, with the same condition (Class 2b)

On good medical therapy with a root under 5.0 cm, the risk of dissection is low. About 20% of people in large series had planned surgery below 5.0 cm.

Daily life

GeneReviews lists some things to avoid. These include contact and competitive sports, isometric exercise such as heavy straining lifts, decongestants, excess caffeine, triptans and LASIK. Its list also includes fluoroquinolone antibiotics. Each choice should be talked through with a cardiologist.

Section recap: Regular scans, a beta blocker or ARB, and well-timed surgery are the core of care. These drugs are guideline-backed but off-label for Marfan in the US and Canada.

Pregnancy and Marfan: what a nationwide registry shows

Pregnancy puts extra strain on the heart and aorta. A large registry from Taiwan helps show how much. It covered 3,337,969 pregnancies from 2004 to 2022. Of these, 794 pregnancies were in 500 women with Marfan.

Outcome	With Marfan	Without Marfan
Severe aortic problem per pregnancy	1.1%, about 1 in 90	0.0005%, about 1 in 200,000
Death of the mother within 42 days	0.1%, about 1 in 1,000	0.02%, about 2 in 10,000

Put another way, about 99 in 100 pregnancies with Marfan had no severe aortic problem. But the risk was far higher than average. Over a mean of 10.7 years, aortic events stayed much more common in mothers with Marfan. The incidence rate ratio was 885.4. An incidence rate ratio, like a hazard ratio, compares how often events happen over time in two groups. Babies were born a bit earlier and smaller, and more needed intensive care.

This registry comes from Taiwan. Whether the same numbers apply to US or Canadian care is not known.

The 2022 ACC/AHA guideline gives clear steps for planning a pregnancy.

• Genetic counseling before pregnancy (Class 1)
• Aortic imaging before pregnancy (Class 1)
• Counseling about the risk of dissection during pregnancy (Class 1)
• Surgery before pregnancy if the root is over 4.5 cm (Class 1)
• Surgery may be considered at 4.0 to 4.5 cm, especially with growth of 0.3 cm or more per year or family history of dissection (Class 2b)

During pregnancy, the guideline advises a team that includes maternal-fetal medicine and cardiology. If possible, delivery should happen where emergency aortic repair is available. A beta blocker is advised during pregnancy and after birth unless there is a reason not to. An echocardiogram is advised each trimester and several weeks after birth. MRI without contrast dye is preferred over CT. Most pregnancy dissections happen in the third trimester or up to 12 weeks after birth.

Once the family variant is known, testing during pregnancy or of embryos before transfer is possible. These are personal choices. A genetic counselor can lay out each option without pressure.

Section recap: In the Taiwan registry, about 1 in 90 pregnancies with Marfan had a severe aortic problem. Planning with a cardiologist and genetic counselor before pregnancy is the guideline’s first step.

Family testing, telling relatives, insurance and the law in the US and Canada

Cascade testing

Cascade testing means testing relatives step by step once a variant is found in one person. The guideline’s advice depends on whether a variant is known.

Family situation	Guideline advice
Pathogenic or likely pathogenic variant found	Genetic counseling and cascade testing of at-risk relatives (Class 1)
Relative inherits the variant	Aortic imaging, by echo or by CT or MRI if needed
No disease-causing variant found in the family	Screening aortic imaging of at-risk relatives (Class 1)

GeneReviews advises clarifying the genetic status of at-risk relatives of any age. Signs can appear in childhood. So the timing for children is worth discussing with a pediatric cardiologist.

Telling relatives

Sharing results can feel hard. Some families use a short letter that explains the variant and suggests a counselor visit. A genetic counselor can help write it or join a family meeting. Think of it as passing on a map, so others can choose their own route.

Insurance and discrimination laws

Protection	What it covers	What it does not cover
US GINA (2008), health insurance	Health insurers cannot use genetic information for coverage or prices	Life, disability and long-term care insurance
US GINA, employment	Employers with 15 or more workers cannot discriminate	Smaller employers and the U.S. military
US ACA (2010)	Health insurers cannot refuse coverage for pre-existing conditions	Life insurance
Canada GNDA (2017)	No one can require a genetic test or its results for goods, services or contracts	A clinical diagnosis

Under GINA, “genetic information” means a person’s gene tests and family medical history. A person’s own diagnosed condition is not part of that definition. For health insurance, the ACA’s rules still protect people with a diagnosis. Some states add more protections for other insurance types.

Canada’s Genetic Non-Discrimination Act also bars collecting or sharing test results without written consent. Health care workers and researchers are exceptions. Penalties can reach $1,000,000 and up to 5 years in prison. The Supreme Court of Canada upheld the law on July 10, 2020, in a 5-4 decision.

Before buying life insurance, it may help to talk with a genetic counselor about timing.

The emotional side

Worry is normal after a Marfan result. Tall teens may feel self-conscious about their bodies. Some people feel guilt about passing on a variant. The Ghent authors themselves noted the stress a diagnosis can bring. Patient groups such as The Marfan Foundation can connect families with others who understand. A counselor or mental health professional can also help.

Section recap: Cascade testing and aortic imaging protect relatives. GINA and Canada’s GNDA give real but limited protection, and life insurance is a gap in the US.

Frequently asked questions

Will a person whose parent has Marfan develop it too?

Each child of an affected parent has a 50 in 100 chance of inheriting the variant. Not everyone with the variant has the same severity. In the All of Us study, 58 of 100 carriers had no Marfan diagnosis in their records. Relatives should ask a cardiologist and genetic counselor about testing and heart scans.

Will children of a parent with Marfan inherit it?

Each child has a 50% chance of inheriting the familial variant. Once the variant is known, children can be tested for it. Those who inherit it need aortic imaging. A pediatric cardiologist can advise on timing.

Does an FBN1 result from 23andMe mean someone has Marfan?

Not by itself. Diagnosis needs body findings such as aortic root enlargement or a slipped lens. A consumer result should be confirmed in a clinical lab. An echocardiogram and eye exam are the next steps.

Will a Marfan diagnosis or FBN1 result affect insurance or employment?

In the US, a law called GINA stops health insurers from using gene test results and family history. It also covers employers with 15 or more workers. It does not cover life, disability or long-term care insurance. The ACA bars health insurers from refusing people for pre-existing conditions. In Canada, the GNDA bars requiring genetic test results for contracts.

Should a family seek a second opinion?

A second opinion can help, most of all before surgery or big life choices. Look for a heart doctor who treats many aorta cases. Also look for a certified genetic counselor (ABGC in the US, CBGC in Canada). For surgery near a threshold, the guideline points to experienced surgeons in a Multidisciplinary Aortic Team.

Summary

Marfan syndrome comes from a change in the FBN1 gene. Each child of an affected parent has a 50 in 100 chance of inheriting it. Diagnosis rests on the aortic root, the eyes and other body features, not on genes alone. Many people with an FBN1 variant found by population testing have no diagnosis.

The main danger is aortic dissection. Type B tears can happen even at normal sizes and after root surgery. Regular scans of the whole aorta, a beta blocker or ARB, and well-timed surgery are the core of care. These drugs are off-label for Marfan in the US and Canada. Pregnancy needs careful planning, since about 1 in 90 pregnancies with Marfan had a severe aortic problem in one registry.

The best next step is a visit with a cardiologist and a certified genetic counselor. Bring any test report and a family history. Sudden severe chest, back or belly pain needs a call to 911.

This article is for educational purposes only. It does not replace diagnosis, treatment or genetic counseling. It is not a substitute for advice from a licensed physician, board-certified medical geneticist, or board-certified genetic counselor. For any decisions about testing, treatment, or care, consult a qualified clinician. In emergencies, call 911.

References

1. MedlinePlus Genetics, NIH/NLM. Marfan syndrome. 2018. https://medlineplus.gov/genetics/condition/marfan-syndrome/
2. Dietz H. FBN1-Related Marfan Syndrome. GeneReviews, University of Washington. 2001, updated 2022. https://www.ncbi.nlm.nih.gov/books/NBK1335/
3. Loeys BL, Dietz HC, Braverman AC, et al. The revised Ghent nosology for the Marfan syndrome. J Med Genet. 2010. https://pubmed.ncbi.nlm.nih.gov/20591885/
4. Isselbacher EM, Preventza O, Hamilton Black J 3rd, et al. 2022 ACC/AHA Guideline for the Diagnosis and Management of Aortic Disease. Circulation. 2022. https://pmc.ncbi.nlm.nih.gov/articles/PMC9860464/
5. Felker SA, Korf BR, Barsh GS. Genotype-first assessment of presentation and penetrance of neurofibromatosis type 1, autosomal dominant polycystic kidney disease, and Marfan syndrome within the All of Us research program cohort. Genet Med. 2026. https://pubmed.ncbi.nlm.nih.gov/41277540/
6. Narula N, Devereux RB, Arbustini E, et al. Risk of Type B Dissection in Marfan Syndrome: The Cornell Aortic Aneurysm Registry. J Am Coll Cardiol. 2023. https://pubmed.ncbi.nlm.nih.gov/37930285/
7. Korukonda S, Byers PH, Kovuri P, et al. Genotype-aortic phenotype correlations in Marfan syndrome: a systematic review and meta-analysis of Fibrillin-1 variants. Heart. 2025. https://pubmed.ncbi.nlm.nih.gov/41309212/
8. Chang FC, Chen CY, Hsieh MJ, et al. Maternal and neonatal outcomes in Marfan syndrome: a nationwide registry. Heart. 2026. https://pubmed.ncbi.nlm.nih.gov/41475970/
9. Lacro RV, Dietz HC, Sleeper LA, et al., Pediatric Heart Network Investigators. Atenolol versus losartan in children and young adults with Marfan’s syndrome. N Engl J Med. 2014. https://pubmed.ncbi.nlm.nih.gov/25405392/
10. Pitcher A, Spata E, Emberson J, et al., Marfan Treatment Trialists’ Collaboration. Angiotensin receptor blockers and beta blockers in Marfan syndrome: an individual patient data meta-analysis of randomised trials. Lancet. 2022. https://pubmed.ncbi.nlm.nih.gov/36049495/
11. Richards S, Aziz N, Bale S, et al., ACMG Laboratory Quality Assurance Committee. Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med. 2015. https://pubmed.ncbi.nlm.nih.gov/25741868/
12. U.S. FDA, Drugs@FDA and drug labels. FDA approval and labeled indications for losartan, atenolol and irbesartan. https://www.accessdata.fda.gov/scripts/cder/daf/index.cfm?event=overview.process&ApplNo=020386
13. Health Canada, Drug Product Database and Product Monographs. Health Canada market status and authorized indications for losartan, atenolol and irbesartan. https://health-products.canada.ca/dpd-bdpp/info?lang=eng&code=19167
14. NHGRI, U.S. EEOC, Government of Canada and Supreme Court of Canada. Genetic discrimination protections in the US (GINA, ACA) and Canada (GNDA). https://www.genome.gov/about-genomics/policy-issues/Genetic-Discrimination and https://laws-lois.justice.gc.ca/eng/acts/G-2.5/FullText.html and https://www.scc-csc.gc.ca/judgments-jugements/cb/2020/38478
15. 23andMe clinician guide (company page). Hereditary disease results: conditions covered (exome sequencing vs genotyping array). https://www.23andme.org/en-int/clinicians/understand-results/hereditary-disease/

Last updated: 2026-10-30

Author: Yu Mizuno (Editor-in-Chief, non-physician), GeneLumen editorial team. This article aggregates 15 sources (tier 1=8 / tier 2=6 / tier 4=1). Sources include NIH MedlinePlus, GeneReviews, the 2022 ACC/AHA guideline and ACMG/AMP standards. They also include the FDA, Health Canada, NHGRI, the U.S. EEOC and the Government of Canada.

This article is for educational purposes only and is not a substitute for medical advice from a licensed physician, board-certified medical geneticist, or board-certified genetic counselor. It does not replace diagnosis, treatment or genetic counseling. In emergencies, call 911.

Related: Genetic Diseases category

🇯🇵 For readers in Japan — a separate Japanese edition written for Japan’s healthcare system (not a translation): https://genelumen.com/ja/ja-genetic-diseases/marfan-syndrome-fbn1-genetics-ja