RAD18 and Alzheimer disease: Yi et al. (2019) found a downregulated level of MEG3 in AD mice. They proved that upregulation of MEG3 could decrease Aβ expression, reduce inflammation injury, and protect neurons by phosphatidylinositol 3-kinase (PI3K)/protein kinase B (Akt) pathway. RAD18 is a member of the chromosome family responsible for repairing DNA damage (Hedglin and Benkovic, 2015). NAT-RAD18 is a lncRNA of the natural antisense transcript against RAD18. It was found that RAD18 expression was down-regulated, while NAT-RAD18 level was up-regulated in response to Aβ40 (Parenti et al., 2007).