Increased HERV expression from different families, as HERV-W, HERV-K or HERV-H, has been reported in rheumatoid arthritis (RA) [4], psoriasis [5], systemic lupus erythematosus [6] or multiple sclerosis (MS) [7]–[10]. The gene discussed is ERVW-1; the disease is rheumatoid arthritis.