Schizophrenia (SCZ) is a mental disorder characterized by impairments in the perception or expression of reality and by significant social or occupational dysfunction. Typically patients demonstrate disorganized thinking, and experience delusions or auditory hallucinations. Although the disorder is primarily thought to affect cognition, it can also contribute to chronic problems with behaviour and emotion. There is no objective biological test for schizophrenia, though studies suggest that genetics, epigenetics and environment are important contributing factors. SCZ displays many non-Mendelian characteristics, rendering it as one of the most likely diseases that may be caused by epigenetic factors. Onset of schizophrenia typically occurs in late adolescence or early adulthood, with males tending to show symptoms earlier than females. Evidence for the role of epigenetic factors and potentially the environment comes from the observation that one identical twin does not universally develop schizophrenia if the other one does (discordance).
