Professional and Linguistic Assessments Board (PLAB) Practice Exam

Which hereditary condition is characterized by progressive degeneration of the muscles of the lower leg associated with the fibula?

1. Charcot-Marie-Tooth disease

2. Duchenne Muscular Dystrophy

3. Myotonic Dystrophy

4. Limb-Girdle Muscular Dystrophy

The correct answer is: Charcot-Marie-Tooth disease

Charcot-Marie-Tooth disease is a hereditary condition that primarily affects the peripheral nerves, leading to muscle weakness and atrophy, particularly in the lower legs and feet. It is associated with degeneration in the muscles of the lower leg, which is often evident in individuals with this condition. The term "Charcot-Marie-Tooth disease" encompasses a variety of hereditary neuropathies, but one common form, known as CMT1A, is specifically linked to mutations in the PMP-22 gene. This condition can lead to muscle degeneration around the fibula, resulting in a characteristic "stork leg" appearance due to muscle wasting. The other conditions listed have different pathophysiological mechanisms or clinical presentations. Duchenne Muscular Dystrophy primarily affects boys and is characterized by progressive muscle weakness beginning in early childhood, mainly affecting the proximal muscles. Myotonic Dystrophy involves difficulty relaxing muscles and can affect various muscle groups, but the primary issues aren't localized to the lower leg and fibula. Limb-Girdle Muscular Dystrophy typically affects the shoulder and hip girdle muscles rather than those of the lower legs specifically. Thus, the features of Charcot-Marie-Tooth disease align precisely with the characteristics stated in the question.