Is schizophrenia a genetic condition?

A combination of genetic and environmental factors play a role in the development of schizophrenia.[2][3] People with a family history of schizophrenia who suffer a transient psychosis have a 20-40% chance of being diagnosed one year later.[23]

Estimates of heritability vary because of the difficulty in separating the effects of genetics and the environment.[24] The greatest risk for developing schizophrenia is having a first-degree relative with the disease (risk is 6.5%); more than 40% of monozygotic twins of those with schizophrenia are also affected.[3] It is likely that many genes are involved, each of small effect and unknown transmission and expression.[3] Many possible candidates have been proposed, including specific copy number variations, NOTCH4, and histone protein loci.[25] A number of genome-wide associations such as zinc finger protein 804A have also been linked.[26] There appears to be significant overlap in the genetics of schizophrenia and bipolar disorder.[27]