Table 2.

Clinical clues for congenital myasthenic syndromes (CMS) subtypes in our cohort

CMS subtype	Clinical Clues	Rare symptoms/sign s	EMG	Response to treatment
Acetylcholine receptor deficiency	Neonatal period Onset with poor suck and cry Marked ptosis and opthamoplegia Mild bulbar symptoms Weakest muscles triceps and iliopsoas Frequent quadriceps femoris weakness (in contrast to MG) Strong tibialis anterior (as in MG) Improvement with age	Asymmetric ptosis Double vision Severe exacerbations with infections	Decremental response to RNS	Improvement with pyridostigmine
Endplate acetylcholinesterase deficiency	Severe bulbar symptoms since birth Mild ptosis Slow pupillary light reflex may be present Frequent scoliosis Distal>Proksimal muscle weakness Persistent respiratory problems in adulthood		Decremental response to RNS Repetitive CMAPs	Deterioration with pyridostigmine Improvement with ephedrine/salbutamol
Slow-channel syndrome	Onset in early childhood- adulthood Variable clinical phenotypes Distal>Proksimal muscle weakness May have respiratory problems	Severe hand weakness/atrophy Pes cavus	Decremental response to RNS Repetitive CMAPs	Deterioration with pyridostigmine Improvement with fluoxetine and ephedrine/salbutamol
CMS subtype	Clinical Clues	Rare symptoms/signs	EMG	Response to treatment
Fast-channel syndromes	Variable clinical phenotypes		Decremental response to RNS	Marked improvement with pyridostigmine Additional benefit from salbutamol
GFPT1 deficiency	Limb girdle phenotype No facial muscle weakness	Hypotonia at birth Prominent involvement of distal limb muscles	Decremental responses to RNS Myopathic MUPs	Improvement with pyridostigmine Additional benefit from 3,4-DAP and salbutamol
DOK 7 deficiency	Limb girdle phenotype No facial muscle weakness		Decremental responses to RNS Myopathic MUPs	No improvement with pyridostigmine Marked improvement with salbutamol
Choline acetyltransferase (ChAT) deficiency	Hypoventilation episodes requiring intubation Mild ptosis and generalized weakness		Decremental response, occurring only after exercise followed by slow recovery in over 15 minutes	Improvement with pyridostigmine and salbutamol
Desmin deficiency related CMS	Myopathic face, symmetric ptosis, ophthalmoparesis, generalized weakness and atrophy Cardiomyopathy		Decremental responses to RNS Myopathic MUPs	Improvement with salbutamol

RNS= repetitive nerve stimulation, MUP=motor unit potential, CMAPs= compound muscle action potentials