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Study finds substantial genetic risk for schizophrenia

Analysis of nationwide twin data from Denmark estimated heritability of schizophrenia at 79%, indicating a significant genetic risk.

“The new estimate of heritability of schizophrenia, 79%, is very close to the high end of prior estimates of its heritability,” John H. Krystal, MD, editor of Biological Psychiatry, said in a press release. “It supports the intensive efforts in place to try to identify the genes contributing to the risk for developing schizophrenia.”

To update heritability estimates for schizophrenia, researchers combined two nationwide registers — the Danish Twin Register and the Danish Psychiatric Research Register — to identify a sample of twins born between 1951 and 2000. Analysis included 31,524 twin pairs, who were followed until June 1, 2011.

Researchers found a probandwise concordance rate of schizophrenia in 33% of monozygotic twins and 7% in dizygotic twins.

Heritability of schizophrenia was estimated at 79%.

Estimated heritability was comparable, at 73%, when expanding illness outcome to include schizophrenia spectrum disorders.

“This study is now the most comprehensive and thorough estimate of the heritability of schizophrenia and its diagnostic diversity. It is interesting since it indicates that the genetic risk for disease seems to be of almost equal importance across the spectrum of schizophrenia,” Rikke Hilker, MD, PhD, study researcher with Copenhagen University Hospital, said in the release. “Hence, genetic risk seems not restricted to a narrow illness definition, but instead includes a broader diagnostic profile.” – by Amanda Oldt

Disclosures: The authors report no relevant financial disclosures.