Cardiomyopathies · Biochemistry and Molecular Biology · NBME-Style
Cardiomyopathies — NBME-style practice question
A physician-validated, board-style question from the Active Transport QBank. Try it, then check the reasoning for every option.
A 28-year-old man presents with fatigue and exertional dyspnea. He has a family history of heart failure in his father and grandfather. Physical examination reveals an irregularly irregular pulse and signs of heart failure. Echocardiography shows biventricular dilation and systolic dysfunction. Genetic testing reveals a mutation in the TTN gene. Which of the following best describes the inheritance pattern of this condition?
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A
MitochondrialIncorrect. Mitochondrial inheritance is maternal-only; the affected father and grandfather argue against this pattern.
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B
Y-linkedIncorrect. Y-linked transmission would skip female carriers and is not described for TTN-mediated DCM.
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C
Autosomal dominantCorrect. TTN truncating mutations cause familial DCM with autosomal dominant inheritance through paternal line.
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D
X-linked recessiveIncorrect. X-linked recessive (e.g., dystrophin) typically affects males with carrier mothers, not paternal transmission.
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E
Autosomal recessiveIncorrect. Autosomal recessive DCM is rare; family history through father/grandfather fits dominant transmission.
↑ Tap an answer to reveal the reasoning
Answer: C. The presence of a TTN gene mutation causing dilated cardiomyopathy suggests an autosomal dominant pattern, as this is the most common inheritance pattern for genetically transmitted DCM. The family history and specific gene mutation support this. X-linked and mitochondrial patterns are less common and not suggested by the family history.
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