Homozygous C-terminal loss-of-function Na_V1.4 variant in a patient with congenital myasthenic syndrome

Congenital myasthenic syndromes (CMS) are a group of rare inherited disorders of neuromuscular transmission.1 Clinical presentations range from predominant ptosis, ophthalmoparesis, facial and bulbar weakness, and generalised muscle weakness to predominant limb girdle weakness with sparing of the eye and face muscles. Symptoms may appear during the neonatal period, late childhood, adolescence or even adulthood. Clinical presentation and response...