The RE are also targeted by autoantibodies in several connective tissue diseases, for example, antibodies against LINE1’s ORF1p or ERV HERV-K’s envelope protein have been described in patients with systemic lupus erythematosus, lupus nephritis, rheumatoid arthritis, Sjogren’s syndrome and mixed connective tissue disease [56–65]. This evidence concerns the gene ERVW-1 and connective tissue disorder.