Congenital myasthenia gravis

Congenital myasthenia gravis usually presents at or close to birth. There are no immunological abnormalities and anti-ACh receptor antibodies are not detectable. It is heterogenous and embraces the following syndromes:

• familial infantile myasthenia - autosomal recessive disease characterised by a pre-synaptic abnormality in acetylcholine synthesis or transport into synaptic vesicles, and a defect in acetylcholine resynthesis by choline acetyltransferase.
  
  
• a sex linked or autosomally recessive condition with an inherited deficiency of acetyl cholinesterase
  
  
• 'slow channel' syndrome in which the acetylcholine receptor ion-channel closes slowly. This prolongs the duration of the end plate potential and permits calcium to accumulate in the post-synaptic region
  
  
• congenital acetylcholine receptor deficiency with extremely simplified end plate anatomy