We first aimed to confirm the contribution of the PFN1 gene (NM_005022.3) to ALS by performing genetic analyses of large cohorts, including a total of 750 French ALS patients (with 150 FALS and 600 SALS) devoid of mutations in C9orf72, SOD1, TARDBP, FUS or UBQLN2. Here, UBQLN2 is linked to amyotrophic lateral sclerosis.