Marfan Syndrome — Symptoms, Causes & Treatment | MyMedicPlus

Marfan syndrome is an autosomal dominant heritable connective tissue disorder caused by mutations in the FBN1 gene encoding fibrillin-1 — a structural glycoprotein critical to extracellular matrix integrity and tissue elasticity — affecting the cardiovascular system, musculoskeletal system, and ocular structures. It affects approximately 1 in 5,000-10,000 people globally, with equal sex distribution and no ethnic predilection. Approximately 25% of cases arise from de novo (new) FBN1 mutations with no family history. Fibrillin-1 deficiency impairs microfibril formation in elastic tissues (aortic wall, lens zonules, skeletal connective tissue) and dysregulates TGF-beta signalling — a key pathway in vascular smooth muscle and extracellular matrix homeostasis — accelerating aortic wall weakening and aneurysm formation. The most life-threatening manifestation is progressive dilatation of the aortic root (aortic sinus) — creating risk of aortic dissection (Type A — at the ascending aorta) and rupture, which were historically the primary cause of early death; in untreated patients the average age of death was 32 years. With modern management including beta-blockers or losartan, surveillance echocardiography, and elective prophylactic aortic root surgery, life expectancy approaches that of the general population. Clinical diagnosis uses the revised Ghent nosology (2010), which recognises the cardiovascular manifestations — particularly aortic root Z-score and ectopia lentis — as the central diagnostic features, with systemic skeletal and other features providing supporting evidence.

Marfan syndrome is caused by heterozygous loss-of-function or dominant-negative mutations in FBN1 (fibrillin-1 gene, chromosome 15q21.1). Over 3,000 pathogenic FBN1 variants have been identified — the vast majority unique to individual families — including missense mutations, frameshift, nonsense, and splice-site variants. FBN1 encodes fibrillin-1, a 350kDa glycoprotein that polymerises into microfibrils — structural elements in elastic fibres throughout the body, particularly prominent in the aortic media, ciliary zonules of the eye, periosteum, and skin. Fibrillin-1 deficiency causes: structural weakening of the aortic wall (reduced elastic lamellae, disorganised smooth muscle) predisposing to progressive dilatation and dissection; inadequate support for the ocular lens (ectopia lentis from weakened zonular fibres); and reduced connective tissue integrity throughout the musculoskeletal system (lax ligaments, dural ectasia). Additionally, fibrillin-1 normally binds and sequesters latent TGF-beta in the extracellular matrix — in Marfan syndrome, excessive free TGF-beta signalling (via SMAD2/3 pathways) promotes smooth muscle apoptosis and matrix metalloproteinase activation, further accelerating aortic degeneration — providing the mechanistic rationale for TGF-beta blocking therapy (losartan, an ARB that secondarily reduces TGF-beta signalling, and irbesartan). Inheritance pattern: autosomal dominant — a parent with Marfan syndrome has a 50% risk of passing it to each child. 25% arise from de novo mutations (no affected parent) — associated with advanced paternal age. Related conditions: Loeys-Dietz syndrome (TGFBR1/TGFBR2 mutations — more aggressive aortic disease), MASS phenotype, mitral valve prolapse syndrome, and ectopia lentis syndrome — all part of the FBN1-related spectrum.

Marfan syndrome affects multiple organ systems with variable expressivity — even within the same family sharing an identical FBN1 mutation. Cardiovascular manifestations: aortic root dilatation — the most clinically critical feature, typically asymptomatic until severe; aortic regurgitation (AR) from aortic root dilatation stretching the aortic valve annulus — causing an early diastolic murmur, and eventually heart failure symptoms (dyspnoea, reduced exercise tolerance, orthopnoea); mitral valve prolapse (MVP) with or without mitral regurgitation (MR) — palpitations, a midsystolic click, and late systolic murmur; aortic dissection (Type A) — sudden severe tearing chest pain radiating to the back, interscapular region, and jaw, with haemodynamic compromise and signs of organ malperfusion — a medical emergency. Ocular manifestations: ectopia lentis (upward, bilateral lens subluxation — present in 50-80% of patients, pathognomonic for Marfan syndrome when combined with aortic features); myopia (often severe, correctable); increased risk of retinal detachment (5-20%) and early cataract formation. Musculoskeletal manifestations: tall stature with disproportionate limb length (arm span exceeds height; lower segment exceeds upper segment); arachnodactyly (long fingers — positive Walker-Murdoch wrist sign: thumb and fifth finger overlap when grasped around the opposite wrist; positive Steinberg thumb sign: thumb abducted beyond the ulnar border of the palm); pectus excavatum (funnel chest — deepest form) or pectus carinatum (pigeon chest); scoliosis (>20° curvature present in 40-60%); pes planus (flat feet); hindfoot valgus; facial features — dolichocephaly (elongated skull), high arched palate, dental crowding, malar hypoplasia, deep-set eyes, retrognathia. Dural ectasia: widening of the dural sac surrounding the spinal cord, predominantly in the lumbosacral region — detected on MRI; may cause low back pain, proximal leg pain, headache, and pelvic pain from nerve root compression. Pulmonary: spontaneous pneumothorax (from apical bullae — occurs in 4-11% of patients, may be recurrent); sleep apnoea from craniofacial dysmorphology.

Marfan syndrome is diagnosed using the 2010 revised Ghent nosology — which requires: (1) in the absence of family history: aortic root dilatation (Z-score above 2 at any age) plus FBN1 mutation, or aortic root Z-score above 2 plus ectopia lentis, or aortic root Z-score above 3 alone (if systemic score is above 7), or ectopia lentis plus FBN1 mutation with known aortic disease; (2) with confirmed family history: ectopia lentis alone, or systemic score above 7 (skeletal features scoring system), or aortic root Z-score above 2 in an adult. Systemic score assigns points for: wrist and thumb signs (3), pectus carinatum (2), hindfoot deformity (2), pneumothorax (2), dural ectasia (2), protrusio acetabulae (2), reduced upper to lower segment ratio (1), scoliosis (1), reduced elbow extension (1), facial features (1), skin striae (1), myopia (1), MVP (1). Echocardiography is the cornerstone investigation for cardiovascular monitoring: annual transthoracic echocardiogram (TTE) measuring aortic root diameter (at the level of the sinuses of Valsalva) and calculating Z-score adjusted for age and body surface area — a Z-score above 2 is abnormal; the rate of aortic growth (more than 3mm/year) guides surgical timing. MRI or CT angiography of the entire aorta for initial assessment and pre-surgical planning — identifies arch, descending aortic, and iliac aneurysms. Slit-lamp examination by ophthalmologist for ectopia lentis (often requires pupil dilation to visualise subluxation). Spine MRI for dural ectasia assessment in symptomatic patients. Genetic testing: FBN1 sequencing and deletion/duplication analysis confirms the diagnosis, guides family member screening, and assists prenatal diagnosis; negative FBN1 testing does not exclude Marfan syndrome (15-20% of clinically confirmed cases have no identifiable FBN1 variant with current techniques — testing of TGFBR1, TGFBR2, SMAD3, and ACTA2 may be needed for differential diagnosis).

Management of Marfan syndrome requires a multidisciplinary team comprising a cardiologist (ideally with expertise in heritable aortopathy), cardiovascular surgeon, ophthalmologist, orthopaedic surgeon, and clinical geneticist. Medical therapy to retard aortic root dilatation: beta-blockers (atenolol, propranolol) reduce aortic root diameter growth rate by reducing heart rate and cardiac contractility, decreasing shear stress on the aortic wall — started at diagnosis and continued lifelong; losartan (Cozaar — angiotensin receptor blocker) targets TGF-beta pathway dysregulation and reduces aortic root growth rate; COMPARE and AIMS trials demonstrated that losartan reduces aortic root growth to a comparable degree to atenolol; combined losartan plus atenolol shows no additional benefit over single-agent therapy in the COMPARE trial. Blood pressure control: target systolic BP below 120mmHg to minimise aortic wall stress; ACE inhibitors or ARBs preferred. Avoid high-intensity cardiovascular exercise and contact sports — isometric exercise (weightlifting, heavy resistance) generates pressure transients that stress the aortic wall; moderate aerobic exercise (swimming, cycling, walking) is recommended; basketball, squash, and contact sports are contraindicated. Prophylactic elective aortic root surgery: indicated when aortic root diameter reaches 4.5cm in adults (or 4.0cm if rapid growth above 3mm/year, family history of dissection below 5cm, planned pregnancy, or severe AR) — cardiovascular surgical guidelines. Valve-sparing aortic root replacement (David procedure — reimplantation technique) preserves the native aortic valve while replacing the dilated sinus segment — preferred in young patients with competent aortic valve; Bentall procedure (aortic root and valve replacement with mechanical composite graft) for significant AR or valve tissue not suitable for repair. Prophylaxis of infective endocarditis: recommended for all patients with MVP and MR and those with prosthetic valves. Lens management: optical correction (spectacles, contact lenses) for ectopia lentis and myopia; cystectomy-aphakia with secondary IOL implantation for severe subluxation causing unacceptable vision. Orthopaedic: bracing for moderate scoliosis (20-45°); spinal fusion for progressive scoliosis above 45°; physiotherapy for pectus, pes planus, and back pain.

Acute aortic dissection (Type A — involving the ascending aorta) is the most feared and immediately life-threatening complication — occurring in up to 15% of untreated patients before the age of 40, presenting as sudden severe tearing chest pain, haemodynamic compromise, and signs of malperfusion (stroke, limb ischaemia, mesenteric ischaemia, cardiac tamponade); mortality is 1-2% per hour without emergency surgical repair (Bentall or David procedure). Risk is highest when the aortic root exceeds 5.0cm or growth rate exceeds 10mm/year. Type B dissection (descending aorta) also occurs in Marfan syndrome and is managed conservatively unless complicated. Aortic regurgitation (AR) from aortic root dilatation causing incomplete leaflet coaptation — causes progressive left ventricular dilatation, volume overload, and systolic dysfunction if untreated; requires aortic valve repair or replacement. Retinal detachment: risk is 5-20% in Marfan syndrome vs 0.03% in the general population — from vitreous traction on retinal tears facilitated by myopia and lens subluxation; requires prompt ophthalmological assessment for any new floaters or curtain-like visual field defect. Spontaneous pneumothorax from rupture of apical pleural blebs (4-11% lifetime risk) — presents with pleuritic chest pain and dyspnoea; recurrent pneumothorax requires pleurodesis. Scoliosis above 40° causes respiratory compromise, chronic pain, and cosmetic deformity. Dural ectasia may cause chronic low back pain, proximal leg pain, and headache unresponsive to standard analgesia, requiring specialist pain management. Endocarditis in those with significant MVP or prosthetic valves.

Prevention of the most serious complication — aortic dissection — is the cornerstone of Marfan syndrome management and requires lifelong surveillance with annual echocardiography, adherence to beta-blocker or losartan therapy, activity modification, and elective surgery before the aortic root reaches dissection threshold. Activity restrictions: avoid all competitive contact sports (American football, boxing, martial arts, basketball, hockey), isometric heavy-load exercise (powerlifting, heavy weightlifting), and sports with risk of collision; moderate-intensity aerobic exercise (cycling, swimming, low-impact aerobics) is encouraged and safe at aortic diameters below 4.5cm. Blood pressure monitoring and control is essential — home BP monitoring with systolic target below 120mmHg in adults; avoid NSAIDs (raise blood pressure) and decongestants (sympathomimetic — raise heart rate). Pregnancy: Marfan syndrome significantly increases maternal aortic dissection risk during pregnancy and the peripartum period (highest risk when aortic root above 4.0-4.5cm); pre-conception specialist counselling with cardiologist and maternal-foetal medicine; close surveillance with echocardiography every 6-8 weeks during pregnancy; planned Caesarean section for aortic root above 4.0cm. Genetic counselling: autosomal dominant condition — each child has 50% risk of inheriting the FBN1 mutation; preimplantation genetic testing (PGT-M) is available for couples wishing to prevent transmission; cascade genetic screening of first-degree relatives (all must have FBN1 testing or clinical evaluation). Family screening: all first-degree relatives of a confirmed Marfan patient should be clinically assessed and offered FBN1 genetic testing — early identification enables prophylactic monitoring and medication before complications occur. Endocarditis prophylaxis: antibiotic prophylaxis before dental procedures for patients with significant MVP plus mitral regurgitation and all patients with prosthetic heart valves.

Call emergency services (999/112) immediately for: sudden, severe, tearing chest pain — often described as the 'worst pain ever' — radiating to the back, between the shoulder blades, and jaw; any sudden severe pain in a known Marfan patient (possible aortic dissection — a surgical emergency with 1-2% per hour mortality without intervention); sudden onset of breathlessness and sharp one-sided chest pain (spontaneous pneumothorax — may require chest drain); sudden visual loss, curtain-like visual field defect, or floaters in a Marfan patient (retinal detachment — requires same-day ophthalmological assessment and surgical repair within 24 hours to prevent permanent visual loss). See a cardiologist or your Marfan specialist as soon as possible for: a new aortic regurgitation murmur; increasing breathlessness or reduced exercise tolerance; significant increase in aortic root dimensions on echocardiography compared to the previous measurement; or pregnancy planning (aortic dissection risk is substantially elevated during pregnancy and requires pre-conception specialist review). If you have tall stature, long limbs, flexible joints, high arched palate, and unexplained eye or heart problems, ask your GP about referral to a clinical geneticist or cardiologist for Marfan syndrome evaluation — early diagnosis allows preventive management before life-threatening complications occur.