Efficacy of ephedrine treatment in COLQ-related Congenital Myasthenic Syndrome (CMS): longitudinal quantitative assessment in a 71-year-old man.

Introduction and aims: We describe a case of long-living COLQ-related congenital myasthenic syndrome (CMS) benefitting from ephedrine with an overall improvement quantified with functional measures. Results: A 71-year-old man was referred with limb-girdle/axial myopathy and fatigability since infancy. In his thirties, a decremental response was observed at 3Hz-nerve stimulation, although testing seronegative for anti-neuromuscular junction antibodies. Later, whole exome sequencing (WES)identified a homozygous likely pathogenic variant in COLQ. After 6-month ephedrine treatment, the patient doubled the distance in the 6-minute-walk test and reached 10 metres in half of the time. His forced vital capacity (FVC) and first-second-forced expiratory volume (FEV1) increased, as well as all patient-reported outcomes. At the 12-month mark, the overall improvement remained consistent/further enhanced, except for a slight decrease in FVC. Conclusions: This case confirms the efficacy of ephedrine treatment with global improvements in a COLQ-CMS in their late adulthood, demonstrated by quantitative outcome measures. Such indicators may be of interest in upcoming CMS therapeutical trials.