Whilst ˪-arginine administration appears to be beneficial both in the mdx mouse and DMD patients, the significantly reduced nNOS content evident in DMD patients suggests that there is a limited therapeutic application for ˪-arginine unless concomitant increases in nNOS expression could be achieved, or alternative isoforms of NOS could be exploited (i.e. through iNOS as per ʟ-citrulline therapy). Here, NOS1 is linked to Duchenne muscular dystrophy.