CNTNAP3 (contactin associated protein family member 3) is a synaptic adhesion molecule critical for nervous system development and behavior. Primary function: CNTNAP3 interacts with synaptic adhesion proteins Neuroligin1/2 and scaffolding proteins PSD95/Gephyrin to regulate synapse development 1. Mechanistically, CNTNAP3 plays opposite roles in controlling excitatory and inhibitory synapse development, with autism spectrum disorder (ASD) mutations causing loss-of-function effects 1. In psychiatric contexts, CNTNAP3 expression is regulated by the lncRNA PAXIP1-AS1 through sequestration of transcriptional repressor ZGPAT, and CNTNAP3 upregulation contributes to anxiety, depression-like behaviors, and social deficits in schizophrenia and bipolar disorder models 2. Disease relevance: Cntnap3-null mice exhibit social interaction deficits, spatial learning impairments, and repetitive behaviors characteristic of ASD 1. CNTNAP3 mutations are identified in ASD cohorts and linked to language impairment phenotypes 3. Beyond neurobehavioral disorders, CNTNAP3 functions in broader cellular processes: the circular RNA derived from CNTNAP3 (circCNTNAP3) suppresses esophageal squamous cell carcinoma progression through p53 regulation 4, and CNTNAP3 appears as a deleterious mutation target in alcohol use disorder 5. Clinical significance: CNTNAP3 emerges as a pleiotropic gene relevant to psychiatric and developmental disorders, with potential therapeutic implications across ASD, schizophrenia, bipolar disorder, and cancer.