Question:medium
A 25-year-old man presents for a routine physical examination. The patient is tall and on examination he was found to have an early diastolic murmur. His family pedigree is given below. Which of the following is the mode of inheritance by which the disease is likely to be transmitted?
A 25-year-old man presents for a routine physical examination. The patient is tall and on examination he was found to have an early diastolic murmur. His family pedigree is given below. Which of the following is the mode of inheritance by which the disease is likely to be transmitted?
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Trace the pedigree: trait in every generation with male-to-male transmission narrows it to one pattern.
Updated On: Jun 23, 2026
- AD
- AR
- XLR
- XLD
Show Solution
The Correct Option is A
Solution and Explanation
Quick pedigree drill: when a condition shows up in every generation, hits both sexes, and you can spot a father passing it to a son, you are looking at an autosomal dominant trait. X-linked is killed off by male-to-male transmission, and recessive patterns usually skip generations, so options (b), (c) and (d) all fall away.
The clinical picture seals it. A tall patient with an early diastolic murmur of aortic regurgitation is a textbook Marfan syndrome presentation, caused by a fibrillin-1 mutation. Marfan is a classic autosomal dominant connective tissue disorder: a single mutant allele is enough to produce disease because it disrupts a structural protein, and the phenotype varies widely between affected family members.
Therefore the inheritance is $AD$, option (a).
The clinical picture seals it. A tall patient with an early diastolic murmur of aortic regurgitation is a textbook Marfan syndrome presentation, caused by a fibrillin-1 mutation. Marfan is a classic autosomal dominant connective tissue disorder: a single mutant allele is enough to produce disease because it disrupts a structural protein, and the phenotype varies widely between affected family members.
Therefore the inheritance is $AD$, option (a).
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