genes and environmental exposures involved in its genesis. Further research indicates that deletion of the NRXN1 gene increases the risk of schizophrenia. Genomic duplications and deletions on a micro-level – known as copy number variants (CNVs) – often underlie neurodevelopmental syndromes. Genomic-wide scans suggest that individuals with schizophrenia have rare structural variants that deleted or duplicated one or more genes. As these studies only indicate an increased risk, further research is necessary to elucidate the underlying mechanisms of the genesis of cognitive diseases. Intellectual disability and Tourette syndrome Similar to schizophrenia, studies have shown that intellectual disability and Tourette syndrome are also associated with NRXN1 deletions. A recent study shows that NRXN genes 1-3 are essential for survival and play a pivotal and overlapping role with each other in neurodevelopment. These genes have been directly disrupted in Tourette syndrome by independent genomic rearrangements. Another study suggests that NLGN4 mutations can be associated with a wide spectrum of neuropsychiatric conditions and that carriers may be affected with milder symptoms. See also Cell adhesion molecule Synaptogenesis References External links Scientists finger neurexin 1 defects in autism Human proteins Molecular neuroscience