Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disorder of the motor pathways, invariably leading to death within a few years of onset. Most cases of ALS are sporadic, but familial forms of the disease (FALS) constitute 10% of the cases. Since the first identification of a causative gene in the 1990s and with recent advances in genetics, more than twenty genes have now been linked to FALS. This increased number of genes led to a tremendous amount of research, clearly contributed to a better understanding of the pathophysiology of this disorder, and paved the way for the development of new therapeutics and new hope for this fatal disease. •Familial amyotrophic lateral sclerosis (FALS) represents <10% of the total ALS patients.•FALS are mainly due to the mutations of four genes: C9ORF72, SOD1, FUS and TDP-43.•The increased number of genes has clearly contributed to a better understanding of the pathophysiology of ALS.•This increased number of genes also risk to led to difficulties to their classification.•Gene therapy is probably a therapeutic way to explore in ALS.