DLGAP2 encodes SAP90/PSD-95-associated protein 2 (SAPAP2), a postsynaptic scaffolding protein that regulates synaptic function and cognitive processes 1. The protein localizes to the postsynaptic density of glutamatergic synapses where it modulates synaptic plasticity and neurotransmission 2. DLGAP2 undergoes alternative splicing with tissue-specific expression patterns in brain and testis 1. The gene plays a complex role in cognitive function, as overexpression impairs synaptic plasticity and exacerbates Alzheimer's disease-related memory deficits in mouse models 3. Conversely, lower cortical DLGAP2 expression is associated with increased amyloid plaques, neurofibrillary tangles, and accelerated cognitive decline in Alzheimer's disease patients 4. DLGAP2 is subject to extensive epigenetic regulation through DNA methylation, which influences its expression and function 5. Clinically, DLGAP2 variants and methylation changes are associated with multiple neuropsychiatric conditions including schizophrenia, alcohol dependence, autism spectrum disorders, and developmental delays 267. The gene appears to serve as a critical interface between genetic susceptibility and environmental factors in neurodevelopmental and psychiatric disorders, with methylation status potentially serving as a biomarker for treatment response in alcohol dependence 6.