Spinal Muscular atrophy (SMA) is a severe neuromuscular disease characterized by loss of spinal a-motor neurons, resulting in the paralysis of skeletal muscle. SMA is caused by deficiency of survival motor neuron (SMN) protein levels. Recent evidence has highlighted an axon-specific role for SMN protein, raising the possibility that axon degeneration may be an early event in SMA pathogenesis. The Wallerian degeneration slow (Wld(s)) gene is a spontaneous dominant mutation in mice that delays axon degeneration by approximately 2-3 weeks. We set Out to examine the effect of Wld(s) on the phenotype of a Mouse model of SMA. We found that Wld(s) does not alter the SMA phenotype, indicating that Wallerian degeneration does not directly contribute to the pathogenesis of SMA development. (C) 2008 Elsevier Inc. All rights reserved.