In addition, this ALS phenotype, presenting with upper and lower motor neuron involvement with normal sensory findings, is clinically distinct and contrasts the SPTLC2-associated HSAN1 phenotype, which is characterised by early onset of sensory loss, sensory neuropathy and variable autonomic involvement, and in later stages, mild motor neuropathy.13 14. This evidence concerns the gene SPTLC2 and amyotrophic lateral sclerosis.