Importantly, HERVs are also silenced by KAP1-mediated heterochromatinization (Rowe et al., 2013; Hurst and Magiorkinis, 2017; Yang et al., 2017; Wolf et al., 2020) and aberrant expression of HERVs, and in particular ERVW-1, encoding the functional relic of a viral envelope protein, Syncytin-1, are associated with a variety of cancers and autoimmune/inflammatory conditions (Bjerregaard et al., 2006; Maliniemi et al., 2013; Grandi and Tramontano, 2018; Wang et al., 2018; Gao et al., 2021). The gene discussed is ERVW-1; the disease is cancer.