ERVW-1 and multiple sclerosis: Additionally, we investigated HERV-W, which has previously been associated with multiple sclerosis, schizophrenia and chronic inflammatory demyelinating polyneuropathy [17], in the same ALS and control samples by estimating its env RNA expression using a similar RT-qPCR method, to exclude it as a possible cause of the previously observed raised levels of serum reverse transcriptase in ALS.