Driven by the presence of MSRV-Env in a small number of CIDP patients (5 out of 8) [120], Faucard et al. confirmed an upregulation of MSRV env and/or pol mRNAs in ~50–65% of CIDP patients PBMC [153]. The gene discussed is ERVW-1; the disease is chronic inflammatory demyelinating polyradiculoneuropathy.