A congenital structural myopathy characterized by generally non-progressive muscle weakness of varying severity; certain muscle fibers show the presence of rod-like structures called nemaline bodies. [ http://purl.obolibrary.org/obo/ECO_0007638 http://purl.obolibrary.org/obo/ECO_0007637 http://purl.obolibrary.org/obo/ECO_0007636 ]