Aberrant DNA methylation has been linked to many AD susceptibility genes, including amyloid precursor protein (APP), β- and γ-secretases 153-156, apolipoprotein E 157, 158, Triggering receptor expressed on myeloid cells 2 (TREM2) 159, hTERT 160, cAMP responsive element binding protein (CREB)-regulated transcription coactivator 1 (CRTC1) 161, brain-derived neurotrophic factor (BDNF) 162, thromboxane A2 receptor (TBXA2R, related to CREB activation), sorbin and SH3 domain-containing 3 (SORBS3, related to synapse formation), and spectrin beta 4 (SPTBN4, related to axon initial segment) 163. The gene discussed is BDNF; the disease is Alzheimer disease.