[P3-144] Two Brothers with Congenital Myasthenic Syndrome Followed for Congenital Myopathy
Congenital myasthenic syndrome (CMS) is characterized by muscle weakness and fatigability due to congenital deficits and dysfunction of molecules in neuromuscular junctions. We report two brothers who had been followed for a long time as congenital myopathy cases. Case1: A 32-year-old man, he had shown delayed motor development since infancy. He walked alone at 2 years of age. He was diagnosed with congenital myopathy by muscle biopsy in early childhood. He has needed respiratory support with nocturnal NIPPV since 14 years of age because of muscle weakness and severe scoliosis. Case2: A 30-year-old man, younger brother of Case1, he had shown delayed motor development since infancy. He walked alone at 3 years of age. At 23 years, he suffered from respiratory failure after taking etizolam for anxiety. He recovered the next day after transient mechanical ventilation. Both brothers have a normal intelligence. They can walk a few meters unassisted, but routinely use electric wheelchairs. Their symptoms showed no apparent diurnal fluctuation. Beta-2-agonists help them regain vigor and increase muscle strength. In both brothers, repetitive muscle stimulation tests revealed a significant amplitude decrement. Anti-ACh-R and anti-MuSK antibodies were negative. Anti-LRP4 antibodies were positive only in the younger brother. Both brothers showed homozygous p.G127S mutations in the CMS-causative gene DOK7. In CMS, most patients do not show diurnal fluctuations of symptoms. Thus, CMS is difficult to distinguish from myopathies. Ephedrine and Beta-2-agonists are beneficial in some cases, but caution is needed as some drugs may cause acute exacerbations.