Furthermore, SPG7 variant carriers were overrepresented in two ALS subgroups, i.e. flail arm and flail leg syndrome, whereby flail arm syndrome was significantly more frequent in SPG7 variant carriers (3/9: 33%) versus non-SPG7 variant carriers (17/205: 8%; P = 0.04, two-sided Fisher’s exact test). This evidence concerns the gene SPG7 and amyotrophic lateral sclerosis.