Genetic studies have implicated the evolutionary novel, anthropoid primates-specific gene locus G72/G30 in psychiatric diseases like schizophrenia, bipolar- and panic-disorders. It encodes for a protein LG72 that has been controversially discussed as putative activator or inhibitor of the peroxisomal enzyme D-amino-acid-oxidase (DAO), or as a mitochondrial protein. Here we have generated "humanized" BAC transgenic mice (G72Tg) that express G72/G30 transcripts. In-situ hybridization analysis revealed that G72 mRNAs are prominently expressed in granular cells throughout the brain. Transgenic mice show a number of behavioral phenotypes that are relevant to psychiatric disorders. These phenotypes include deficits in sensorimotor gating, locomotor deficits, increase compulsive behaviors and deficits in smelling. These results identify LG72 as a possible key protein in pathomechanism of psychiatric diseases.