Fibers isolated from a diaphragm specimen had severely reduced maximal Ca2+-activated active tension (4 ± 0.5 mN/mm2 compared with 88 ± 5 mN/mm2 in control) (Figure 4A), which is similar to the recent report of contractile function in fibers of NM patients with NEB exon 55 deletions [17]. This evidence concerns the gene NEB and nemaline myopathy.