For example, autopsy results of AD patients showed a significant increase in m6A levels in astrocytes and microglia in the hippocampus, although immunohistochemistry tests did not show significant changes in the expression levels of m6A-related proteins (including METTL3, METTL14, WTAP, FTO, and YTHDF1), similar to those in hippocampal pyramidal neurons. Here, METTL3 is linked to Alzheimer disease.