A congenital myasthenic syndrome characterized by postsynaptic neuromuscular junction defects, early-onset progressive muscle weakness, and prolonged opening and activity of the acetylcholine receptor channel that has_material_basis_in heterozygous or rarely biallelic mutation in the CHRNE gene on chromosome 17p13. [ http://purl.obolibrary.org/obo/ECO_0007645 ]