Table 2

Distinguishing features of subtypes

Syndrome	Typical age of onset	Typical presenting features		Ophthalmoplegia Other ocular features		Respiratory crises	Other
Choline acetyltransferase deficiency	Birth and infancy	Episodic apnoeas		Absent		+	May be normal between episodes of apnoea
Acetylcholinesterase deficiency	Birth > infancy > childhood	Ptosis, falls, slower movement, poor feeding		Usually present	Slowed pupillary response following constriction to light	+	Chronic hypoventilation
Acetylcholine receptor deficiency	Birth and infancy	Ptosis, poor feeding		Severe			Generally stable course
Rapsyn	Birth and infancy	Crises, ptosis, poor feeding, contractures may require ventilation at birth		Absent	Strabismus: may be convergent or divergent and latent or manifest	+ Often resolve in late childhood	Dysmorphic features
Rapsyn	There is also a milder late onset phenotype with limb weakness ± ptosis			Absent		+ Often resolve in late childhood	Dysmorphic features
DOK7	Early childhood, for example, 2–4 years		Deterioration in walking and falls in a child who has achieved normal milestones	Absent			Limb girdle weakness, tongue wasting, stridor
DOK7	Occasionally onset at birth with stridor and poor feeding			Absent			Limb girdle weakness, tongue wasting, stridor
Slow channel syndrome	Variable birth to adulthood	Hypotonia or weak neck muscles at birth/infancy limb weakness, especially distal upper limb, ptosis, difficulty running		Mild–moderate or absent			Autosomal dominant
Fast channel syndrome	Birth	Respiratory crises/apnoea, ptosis, weak cry, poor feeding/choking may require ventilation at birth		Severe		+ Abrupt	Usually profound weakness
GFPT1, DPAGT1	Early childhood	Deterioration in walking, falls, limb weakness		Absent	Ptosis mild or absent		Little or no facial weakness, tubular aggregates on muscle biopsy

For ophthalmoplegia the typical findings are listed. DOK7, downstream of kinase-7; +, associated with.