In cancers, DNA hypermethylation decreases the expression of tumor suppressor genes, which leads to tumorigenesis.33 In Alzheimer's disease, changes in global and/or gene-specific DNA methylation have been reported.34 However, in POAG, we found that DNA methylation is not the regulatory mechanism responsible for the increased expression of the glaucoma-associated factor sFRP1 in the TM.21,35 MicroRNA regulation also contributes to cancers and neurodegenerative diseases. Here, SFRP1 is linked to neurodegenerative disease.