🏥 USMLE Exam Prep

A 5-year-old boy presents with developmental delay, intellectual disability, and macro-orchidism. Genetic testing reveals an expansion of CGG trinucleotide repeats in the FMR1 gene. What is the most likely mode of inheritance for this condition?

A Autosomal dominant
B Autosomal recessive
C X-linked recessive
D Mitochondrial inheritance

✓ Correct Answer: Option C

The symptoms (intellectual disability, macro-orchidism) and genetic cause (CGG repeat expansion in FMR1 gene) are characteristic of Fragile X syndrome, which is inherited in an X-linked recessive pattern.

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