HERV-K pol transcript expression was significantly increased in the brains of patients with ALS compared with controls as was neuronal HERV-K reverse transcriptase protein expression.Specific genomic loci from which the HERV-K transcripts originated were identified and included a locus unique to the ALS samples.In ALS brain tissue reverse transcriptase expression was positively correlated with TDP-43 and the reverse transcriptase protein colocalised with TDP-43. The gene discussed is TARDBP; the disease is amyotrophic lateral sclerosis.