Current research indicates that reactivation of HERV-K (HML-2) potentially contributes to disease pathogenesis, such as ovarian cancer (Wang-Johanning et al., 2007), prostate cancer (Wang-Johanning et al., 2003a), melanoma (Büscher et al., 2005), rheumatoid arthritis (RA) (Freimanis et al., 2010), systemic lupus erythematosus (SLE) (Balada et al., 2009), as well as multiple sclerosis (MS) (Perron and Lang, 2010). This evidence concerns the gene CLEC10A and rheumatoid arthritis.