ISG15 and multiple sclerosis: Further, we compared the SARS-CoV-2 microglial transcriptomic signature to previously identified human microglial populations identified in autopsy and surgical brain tissues obtained in the Memory and Aging Project (MAP) [38], and found an enrichment with genes in so-called interferon responsive microglia (cluster 4 in this dataset) (Fig. 6f), defined by ISG15 and with increased expression of multiple sclerosis (MS) and AD susceptibility genes.