previously healthy 15-year-old boy is brought to the physician for progressive muscle weakness. Over the past 2 months, he has
had increasing difficulty making facial expressions, including smiling and frowning He also has had difficulty swallowing but has no
pain T he boy takes no medications and his vaccinations are up to date. He was adopted as an infant and his biological family history
is unknown. Physical examination shows ptosis, temporal wasting, thin cheeks, emaciated extremities, atrophy of the thenar and
hypothenar eminences, inverted V-shaped upper lip, and testicular atrophy. Delayed relaxation is noted on contraction of the thenar
and hypothenar muscles. Testicular volume is small for age Neurologic examination shows normal deep-tendon reflexes and a
negative Babinski sign What is the most likely mode of genetic transmission of the patient’s condition?
- QA Autosomal dominant
- 0 B. Autosomal recessive
- 0 C. De novo mutation
- 0 D. X-linked dominant
- 0 E. X-linked recessive
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