🏥 USMLE Exam Prep

A 22-year-old male presents with difficulty walking, impaired speech, and involuntary movements. His father and paternal grandfather had similar symptoms. Genetic testing reveals an expansion of trinucleotide repeats (CAG) in a specific gene. This is an example of which genetic phenomenon?

A Imprinting
B Anticipation
C Mosaicism
D Mitochondrial inheritance

✓ Correct Answer: Option B

Anticipation is a phenomenon where a genetic disorder's symptoms become more severe and/or appear at an earlier age in successive generations. This is characteristic of trinucleotide repeat disorders like Huntington's disease (CAG repeats).

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