METTL3 and Alzheimer disease: The lack of changes in other m6A regulators during MCI phase suggests that METTL3 reduction may be an initiating factor in m6A dysregulation which lead to reduction in other m6A regulators at a later stage during the course of AD because METTL3 and METTL14 form a heterodimeric methyltransferase complex and METTL3 knockdown leads to METTL14 reduction [64].