Neoplasia and Cancer Biology · USMLE Step 1

Which structural gene mutation is more likely to be inherited in familial cancer syndromes: an oncogene or a tumor suppressor gene, and why?

Oncogene — because gain-of-function always requires inheritance
Tumor suppressor gene — one inherited mutant allele predisposes, needing only a 'second hit'
Oncogene — because they cause dominant inheritance
Neither — cancers are never inherited

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Correct answer: Tumor suppressor gene — one inherited mutant allele predisposes, needing only a 'second hit'

In familial cancer syndromes, inheriting one mutated tumor suppressor allele predisposes; a second somatic hit inactivates the remaining allele (two-hit model), leading to neoplasia.

Difficulty: Medium Question 13 of 20

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Which structural gene mutation is more likely to be inherited in familial cancer syndromes: an oncogene or a tumor suppressor gene, and why?

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