As nNOS is predominantly expressed in the type IIB fibers [39], the loss of nNOS activity caused by the dystrophin deficiency is considered to play an important role in the pathogenesis of muscle degeneration in DMD, although there is discrepancy (difference) of nNOS localization in muscle fiber types between human and rodent skeletal muscles. The gene discussed is DMD; the disease is Skeletal muscle atrophy.