Contactin-4, abbreviated as CNTN4, is a brain-derived protein belonging to the immunoglobulin superfamily. It has been found high expression in testes, thyroid, small intestine, uterus and brain. This protein is an neuronal membrane protein that functions as an glycosylphosphatidylinositol- anchored cell adhesion molecule. Contactin-4 is considered as a candidate protein responsible for the differentiation potential of human neuroblastoma cells and it has been implicated in some cases of autism and spinocerebellar ataxia type 16. Studies of the cantactin family have revealed a complex pattern of hemophilic and heterophilic interactions that are required for axon growth and pathfinding. Such studies demonstrate that these essential functions are mediated by the combination and juxtaposition of multiple Ig and FNIII domains. Second, these neuronal adhesion molecules demonstrate highly regulated temporal and spatial expression patterns in the CNS. For this reason, the disruption of the regulatory region of the predominant brain-expressed isoform reasonable would be expected to have significant functional consequences.