An exact cause of schizophrenia has not been found. However, genetics is thought to account for up to 80 percent of the risk of developing the disease. Identical twins have a 48 percent chance of both developing schizophrenia if one twin has the disease, fraternal twins have a 17 percent chance, children of parents with schizophrenia have a 13 percent chance, and siblings have a 9 percent chance of developing the disease.
McGue M, Gottesman II. The genetic epidemiology of schizophrenia and the design of linkage studies. European Archives of Psychiatry and Clinical Neuroscience. 1991;240(3):174-81.
Many genes have been identified that may contribute to the risk of developing schizophrenia, however these are all shown to have a small to moderate risk of disease progression alone.
Umeda-Yano S, Hashimoto R, Yamamori H, Weickert CS, Yasuda Y, Ohi K, Takeda M. Expression analysis of the genes identified in GWAS of the postmortem brain tissues from patients with schizophrenia. Neuroscience Letters. 2014;568:12-6.
Additionally, specific genetic differences have been strongly associated with schizophrenia. These may contribute to problems during brain development and later mental functioning. Yet, they only account for a small number of schizophrenia cases.
Rapoport JL, Giedd JN, Gogtay N. Neurodevelopmental model of schizophrenia: update 2012. Molecular Psychiatry. 2012;17(12):1228-38.
McGue M, Gottesman II. The genetic epidemiology of schizophrenia and the design of linkage studies. European Archives of Psychiatry and Clinical Neuroscience. 1991;240(3):174-81.
