ERVFRD-1 and non-Hodgkin lymphoma: The levels of ERVFRDE1 RNA in Hodgkin and non-Hodgkin lymphomas were similar, but the levels of spliced syncytin-2 mRNA were higher in the non-Hodgkin lymphomas (median 12% of POLR2A) than in the Hodgkin lymphomas (median 6% of POLR2A, Additional file 4: Fig. S2).