TARDBP and amyotrophic lateral sclerosis: In light of these considerations, primary cutaneous fibroblasts from healthy donors, from patients with sporadic ALS (carrying a heterozygous 1144G-A transition in exon 6 of the TARDBP gene, resulting in an A382T substitution in the TDP-43 encoding gene) or from patients with familial ALS without mutations in the most common ALS-related genes were studied to elucidate the mechanisms of L-BMAA toxicity (64).