In conclusion, the transcriptome profiles of the brains of people with HAND and AD highlight opposite expressions of RNA involved in type 1 interferon signaling, including STAT1, ISG15, and IFIT3. The expression of genes involved in this immune response varies in different neurodegenerative diseases and is suggested to be involved in the different neuropathologies that lead to cognitive decline. The gene discussed is ISG15; the disease is neurodegenerative disease.