ERVW-1 and systemic lupus erythematosus: The HERV-H, HERV-K, HERV-W, and HERV-E families are the most studied in relation to the onset and/or progression of several human diseases, but others, such as HTLV-related endogenous sequence-1 (HRES-1), have been described as playing a role in the progression of systemic lupus erythematosus (SLE) and as possible marker of the disease [29].