Decomposition of schizophrenia into neurobiological vulnerability traits is necessary to understand the complex genetic underpinnings of this phenomenologically defined disorder. This issue is discussed with a focus on prepulse inhibition (PPI) as a neurobiological phenotype and the 5HT2a-receptor as a candidate gene. A series of recent studies illuminates that PPI and 5HT2a-receptors present as vulnerability markers for schizophrenia; a functional sequence variant in the 5HT2a-gene is contributing to this relationship and might consequently contribute to the genetic predisposition to schizophrenia with a very small risk increase.