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Marfan Genetic Counselling — EECC MCQ

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ModerateValvular Heart DiseaseMarfan Genetic CounsellingEECC

A 35-year-old man with Marfan syndrome has an aortic root diameter of 48 mm and wishes to have children. He asks about the risk of aortic dissection being inherited. What genetic counselling should be provided?

Educational content. Not a substitute for clinical judgement or local policy.

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Correct answer: D — Marfan syndrome is autosomal dominant with 50% transmission risk to each offspring; prenatal genetic testing and pre-implantation genetic diagnosis are available for known FBN1 mutations

Marfan syndrome is an autosomal dominant connective tissue disorder caused by mutations in the FBN1 gene (fibrillin-1). Each child of an affected parent has a 50% chance of inheriting the condition. However, approximately 25% of cases are de novo mutations. Genetic counselling should cover: (1) 50% transmission risk; (2) variable expressivity (even within the same family, clinical severity varies); (3) prenatal testing options (chorionic villus sampling or amniocentesis for known FBN1 mutations); (4) pre-implantation genetic diagnosis (PGD) available with IVF for known mutations; (5) pregnancy-related aortic risk for the affected parent (aortic dissection risk increases in pregnancy, particularly if root >40 mm). The 2025 ESC CVD in Pregnancy Guidelines classify Marfan with aorta >45 mm as mWHO IV.

Reference: ESC (2025): CVD in Pregnancy; ESC (2024): Aortic Disease Guidelines