Interestingly, the lack of SMN2 gene copies in our patient offers the unique opportunity of selectively studying the impact of the modulation of SMN1 promoter on motoneuron disease phenotype, an issue that might be relevant when thinking that SMN1 duplications have been associated with ALS susceptibility [6] and that the loss of spliceosome integrity (related to SMN function) has been postulated to play a role in ALS [15]. Here, SMN1 is linked to amyotrophic lateral sclerosis.