ERVW-1 and melanoma: These include an overexpression of genes coding for the envelope proteins of human endogenous retroviruses (HERVs), of group W in MS [4-8] and of K in melanoma [62], although the increased amount of the HERV-W ENV protein (syncytin-1) in nerve tissue is neither a genetically determined risk nor a result of an infectious behavior of these elements with a viral ancestry, encoded by the human genome.