Based on these considerations, the aims of the present study were to assess and compare the transcription levels of pol genes of HERV-H, -K, and -W, the three retroviral families most extensively studied [26,33,35]; of env genes of SYN1, SYN2, and MSRV; and of TRIM28 and SETDB1 in the peripheral blood, in the chorion, and in the decidua basalis of the placenta from pregnant women affected or unaffected by MS; in cord blood from their neonates; and in the peripheral blood from healthy women of child-bearing age. The gene discussed is ERVW-1; the disease is myeloid sarcoma.