GeneticsTier 2Medical Sciences concept

Connective tissue disorders and aortic dissection risk (vascular Ehlers-Danlos, Marfan, Loeys-Dietz)

Core concept

Disorder	Gene	Dissection risk profile
Marfan syndrome	FBN1 (fibrillin-1)	Root dilatation precedes dissection; more time to intervene
Loeys-Dietz syndrome	TGFBR1/2, SMAD3	Dissects at smaller diameters, younger age - more aggressive, lower surgical threshold
Vascular Ehlers-Danlos (type IV)	COL3A1	Arterial rupture without warning dilatation - can rupture near-normal diameter; also bowel/uterine rupture

Key detail

Marfan - surgical threshold ~4.5-5.0cm (lower with family history of dissection, rapid growth, or pregnancy planning)
Loeys-Dietz - surgical threshold lower (~4.0-4.2cm) given the more aggressive natural history
Vascular EDS - imaging surveillance itself carries risk (catheter angiography can precipitate rupture) - prefer non-invasive imaging; surgery is high-risk and often reserved for life-threatening rupture

Clinical relevance

Tall, marfanoid habitus + ectopia lentis + aortic root dilatation -> Marfan - confirm with FBN1
Hypertelorism, bifid uvula, arterial tortuosity + dissection at a young age -> Loeys-Dietz
Thin translucent skin, easy bruising, spontaneous arterial/bowel rupture -> vascular EDS - genetic counselling and family screening are critical given the unpredictable rupture risk

Correlations

Marfan syndrome (full clinical note)
Aortic dissection and aortic aneurysm
Ehlers-Danlos syndrome subtypes
Genetic counselling in inherited cardiac conditions

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