A 32-year-old female presents with fluctuating ptosis and diplopia that worsen towards evening. What autoantibody test is most sensitive and specific for this condition?
Answer and explanation
Correct answer: D. Anti-acetylcholine receptor antibody
- Step 1: Fatigable weakness of extraocular and skeletal muscles that worsens with repetitive use indicates myasthenia gravis.
- Step 2: Autoantibodies targeting the nicotinic acetylcholine receptor (AChR) at the neuromuscular junction are detected in approximately 85% of generalized myasthenia gravis cases.
Answer
Anti-acetylcholine receptor antibody.
Why not the others: Antibodies against P/Q-type voltage-gated calcium channels are specific for Lambert-Eaton myasthenic syndrome. Anti-aquaporin-4 antibodies are diagnostic markers for neuromyelitis optica spectrum disorder. Anti-GM1 antibodies are associated with Guillain-Barre syndrome and multifocal motor neuropathy.
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