Molecular Biology/Genetics USMLE Step 1 Practice Question
A 34 year old woman seeks counseling because her father developed gait instability and choreiform movements in middle age. Genetic testing in the family identified a CAG trinucleotide repeat expansion. She asks why affected individuals in successive generations tend to develop symptoms at an earlier age. Which of the following terms best describes this phenomenon?
Answer choices
- AMosaicism
- BIncomplete penetrance
- CAnticipationCorrect answer
- DLoss of heterozygosity
- EVariable expressivity
- FGenetic imprinting
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