Spinal muscular atrophy (SMA) is a devastating neuromuscular disease characterised by progressive loss of spinal motor neurons. Mutations in the genes underlying spontaneous bovine and feline models of SMA have recently been described. The clinical and pathological features of these disorders are similar to human forms of SMA making both genes excellent candidates in patients with motor neuron loss of no known aetiology. Here we report that a screen for mutations in coding regions and splice sites of the LIX1 and FVT1 genes in a cohort of 96 non-5q SMA patients and 119 familial and sporadic Amyotrophic Lateral Sclerosis patients identified no obvious pathogenic changes. This study indicates that mutations in these genes do not contribute significantly to the cause of motor neuron diseases in the human population.