NLGN4Y (neuroligin 4 Y-linked) is a cell surface adhesion protein that functions in synaptic organization and neuronal communication. Located on the Y chrY, NLGN4Y shares 97% sequence homology with its X-linked counterpart NLGN4X and encodes a postsynaptic adhesion molecule that binds to presynaptic neurexins to facilitate synapse formation and maintenance 1. The protein is involved in both excitatory and inhibitory synaptic function, contributing to synaptic assembly and neuron-to-neuron adhesion 1. NLGN4Y has emerged as a candidate gene for autism spectrum disorders (ASD), with evidence suggesting that overexpression may contribute to ASD risk in males with Y chromosome Y like 47,XYY 2. Notably, maternal immune responses against NLGN4Y protein have been associated with male homosexuality, particularly in sons with older brothers 3. In prostate cancer, reduced NLGN4Y expression correlates with higher grade tumors and increased biochemical recurrence risk, suggesting a tumor suppressor role 4. While rare missense variants like p.I679V have been identified in autism patients, the functional significance remains unclear due to limited cosegregation data 5. The gene's expression is male-specific and can be used for forensic sex determination 6.