Which condition is characterized by episodes of muscle weakness and fatigue due to an autoimmune response?

• A. Duchenne muscular dystrophy
• B. Myasthenia gravis
• C. Guillain-Barré syndrome
• D. Huntington's disease

Answer: (B)

Myasthenia gravis is characterized by episodes of muscle weakness and fatigue that occur due to an autoimmune response where the body's immune system mistakenly attacks the acetylcholine receptors at the neuromuscular junction. This interference prevents effective communication between nerves and muscles, leading to the hallmark symptoms of muscle weakness that tends to worsen with activity and improve with rest. Patients may experience weakness in the ocular, facial, bulbar, and limb muscles, resulting in difficulties in movement, eye control, and swallowing.

Other conditions mentioned, such as Duchenne muscular dystrophy, involve genetic causes leading to muscle degeneration and do not primarily focus on an autoimmune response. Guillain-Barré syndrome involves a rapid-onset polyneuropathy often triggered by infections, leading to weakness but not specifically tied to muscle fatigue during episodes. Huntington's disease is a neurodegenerative genetic disorder that leads to the progressive breakdown of nerve cells in the brain, resulting in movement disorders, cognitive decline, and psychological symptoms, but is not characterized by episodes of muscle weakness due to an autoimmune reaction.