Synapsin II is a member of the neuronal phosphoprotein family. These 
phosphoproteins are evolutionarily conserved across many organisms and are 
important in a variety of synaptic functions, including synaptogenesis and the 
regulation of neurotransmitter release. A number of genome-wide scans, 
meta-analyses, and genetic susceptibility studies have implicated the synapsin 
II gene (3p25) in the etiology of schizophrenia (SZ) and other psychiatric 
disorders. Further studies have found a reduction of synapsin II mRNA and 
protein in the prefrontal cortex in post-mortem samples from schizophrenic 
patients. Disruptions in the expression of this gene may cause synaptic 
dysfunction, which can result in neurotransmitter imbalances, likely 
contributing to the pathogenesis of SZ. SZ is a costly, debilitating psychiatric 
illness affecting approximately 1.1% of the world's population, amounting to 51 
million people today. The disorder is characterized by positive (hallucinations, 
paranoia), negative (social withdrawal, lack of motivation), and cognitive 
(memory impairments, attention deficits) symptoms. This review provides a 
comprehensive summary of the structure, function, and involvement of the 
synapsin family, specifically synapsin II, in the pathophysiology of SZ and 
possible target for therapeutic intervention/implications.