TARDBP and amyotrophic lateral sclerosis: In addition to comparing L1 expression with the expression of the gene in which they were located we also compared L1 expression with that of TARDBP. Previous studies have shown that TDP-43 (encoded by the TARDBP gene) regulates the expression of retrotransposons [11, 14, 15] and that the subset of ALS characterised by retrotransposons activation also has lower levels of TARDBP (11).