In 2017, mutations in VAMP1 were implicated in a congenital presynaptic myasthenic syndrome. Since then, nine autosomal recessive cases with hypotonia, facial weakness, fatigability, bulbar involvement and delayed motor acquisition have been described.
- Five new cases were reported in May 2024.
- Their description confirms the severity of the bulbar and motor impairment; all had scoliosis and none was able to stand.
- Pyridostigmine produced only a slight response. Four also received salbutamol with moderate improvement. 3,4-diaminopyridine was added in three children at an average age of 3.5 years, resulting in improved strength and reduced fatigability.
