NEB and nemaline myopathy: Overall, the cases described in this study represent the severe end of the clinical spectrum of NM, exceeding the clinical and physiological deficits observed in patients with deletion of exon 55 of NEB. Additionally, our results imply that low levels of nebulin protein detected by Western blot analysis may correlate with a poor prognosis for patients with NM due to NEB mutations, which would be diagnostically useful if this finding holds true in studies of larger numbers of patients.