An international research group has identified a 15% overlap between inherited schizophrenia and bipolar-disorder attributable to common genetic variation. The Cross Disorders Group of the Psychiatric Genomics Consortium published the study online in Nature Genetics August 11.
The group used genomewide-genotype data from thousands of people and compared them with control subjects. Besides the relationship between schizophrenia and bipolar disorder, there was a 10% inheritability overlap between bipolar disorder and depression, a 9% overlap between schizophrenia and depression, and a 3% overlap between schizophrenia and autism. The common genetic variants with small effects revealed in this and related studies will eventually be supplemented by other research on other variations. Study co-leader Naomi Wray, Ph.D., of the University of Queensland in Australia, said in a statement accompanying the study:
“Shared variants with smaller effects, rare variants, mutations, duplications, deletions, and gene-environment interactions also contribute to these illnesses. Since our study only looked at common gene variants, the total genetic overlap between the disorders is likely higher.”