Alterations in the Number and Affinity of Junctional Acetylcholine Receptors in a Myopathy With Tubular Aggregates

This paper reports the findings in a 32-year-old man who presented in adult life with a myasthenic syndrome characterized by dysphagia, dysphonia, fluctuating ptosis, episodic diplopia and a variable weakness of the limbs and trunk. Electromyography showed a small decremental response, increased neuromuscular jitter and blocking of some components. Histochemical and electron microscopic studies revealed changes in end-plate morphology and prominent tubular aggregations within the muscle fibres. Radiochemical investigations using di-iodinated 125I-alpha-bungarotoxin demonstrated a reduction in the number of AChR and alterations in receptor affinity which suggested an abnormality of the AChR macromolecule.