Learning Resources

• Rogers, (2023). McCance & Huether’s pathophysiology (9th ed.). Elsevier – Evolve.
• Chapter 1: Cellular Biology: Summary Review
• Chapter 2: Altered Cellular and Tissue Biology: Environmental Agents:

Summary Review

• Chapter 3: The Cellular Environment: Fluids and Electrolytes, Acids and Bases: Summary Review
• Chapter 4: Genes and Genetic Diseases: Summary Review
• Chapter 5: Genes, Environment-Lifestyle, and Common Diseases: Summary Review
• Chapter 6: Epigenetics and Disease: 187195; pp. 198199.

A 34-year-old woman presents with 3 months of progressive fatigue and intermittent double vision. She reports that her eyelids droop by the end of the workday and improve after resting. She also notes:

• Difficulty chewing meat at dinner
• Slurred speech in the evenings
• Mild difficulty swallowing solid foods
• Increasing fatigue with prolonged talking

She denies numbness, tingling, muscle pain, or recent illness.

Physical Examination

• Vital signs stable
• Bilateral ptosis (worse with sustained upward gaze)
• Diplopia on lateral gaze
• Speech becomes nasal after prolonged conversation
• Motor strength 5/5 initially, decreases to 4/5 with repeated resistance testing
• Reflexes normal
• Sensation intact

Laboratory Data

Test

Result

CBC

Normal

CMP

Normal

TSH

2.1 IU/mL

ESR

10 mm/hr

ANA

Negative

Test

Result

Acetylcholine receptor antibodies

Elevated

Anti-MuSK antibodies

Negative

Repetitive nerve stimulation shows a decremental response. Chest CT reveals thymic hyperplasia.

Questions:

• Which genetic mutations are commonly associated with the disease?
• Why is the patient presenting with the specific symptoms described?
• Discuss the pathophysiological mechanisms of the disease in

What do the blood test results tell us about the disease and disease progression?