Genetic relationship between five psychiatric disorders estimated from genome-wide SNPs

Most psychiatric disorders are moderately to highly heritable. The degree to which genetic variation is unique to individual disorders or shared across disorders is unclear. To examine shared genetic etiology, we use genome-wide genotype data from the Psychiatric Genomics Consortium (PGC) for cases and controls in schizophrenia, bipolar disorder, major depressive disorder, autism spectrum disorders (ASD) and attention-deficit/hyperactivity disorder (ADHD). We apply univariate and bivariate methods for the estimation of genetic variation within and covariation between disorders. SNPs explained 17–29% of the variance in liability. The genetic correlation calculated using common SNPs was high between schizophrenia and bipolar disorder (0.68 ± 0.04 s.e.), moderate between schizophrenia and major depressive disorder (0.43 ± 0.06 s.e.), bipolar disorder and major depressive disorder (0.47 ± 0.06 s.e.), and ADHD and major depressive disorder (0.32 ± 0.07 s.e.), low between schizophrenia and ASD (0.16 ± 0.06 s.e.) and nonsignificant for other pairs of disorders as well as between psychiatric disorders and the negative control of Crohn’s disease. This empirical evidence of shared genetic etiology for psychiatric disorders can inform nosology and encourages the investigation of common pathophysiologies for related disorders. The current classification of psychiatric disorders reflects clinical syndromes with largely unknown etiology and is based on historical descriptions provided by prominent clinicians over the last 125 years. Family (including twin and adoption) studies provide consistent evidence that genetic factors are involved in these syndromes1. In principle, family studies allow quantification of the shared genetic etiology of disorders, through the estimation of heritability (the proportion of variance in liability attributable to additive genetic factors), and the genetic correlation between them. However, difficulties in ascertaining samples of sufficient size mean that there are few estimates of genetic correlations. Nonetheless, family studies suggest correlated familial genetic liabilities to bipolar disorder and schizophrenia2,3, bipolar disorder and major depressive disorder2,3, and ASD and ADHD4–6 (Supplementary Table 1). Phenotypic and genetic overlap has also been suggested for ASD and schizophrenia7–11, ASD and bipolar disorder9, bipolar disorder and ADHD12, and major depressive disorder and ADHD13. Some of these relationships have been supported by recent evidence of shared molecular risk factors14–16, but the extent of these relationships remains unclear, given the small proportion of risk associated with individually identified variants. The genomics era provides new opportunities to explore the shared genetic etiology of disorders. Genome-wide association studies (GWAS) assess common genetic NIH Public Access Author Manuscript Nat Genet. Author manuscript; available in PMC 2014 September 01. Published in final edited form as: Nat Genet. 2013 September ; 45(9): 984–994. doi:10.1038/ng.2711. N IH -P A A uhor M anscript N IH -P A A uhor M anscript N IH -P A A uhor M anscript polymorphisms (for example, SNPs) at several hundred thousand positions in the genome. © 2013 Nature America, Inc. All rights reserved. Correspondence should be addressed to N.R.W. (naomi.wray@uq.edu.au). *A full list of authors and affiliations appears at the end of the article. 36Université Denis Diderot, Paris, France. 37Assistance Publique–Hôpitaux de Paris (AP-HP), Groupe Hospitalier Saint-Louis, Lariboisiere, F Widal, Departement de Psychiatrie, Paris, France. 42Centre National de la Recherche Scientifique (CNRS) Unité Mixte de Recherche (UMR) 7224, Paris, France. 70Institute of Neuroscience and Medicine (INM-1), Research Center Jülich, Jülich, Germany. 77Biomedical Network Research Centre on Rare Diseases (CIBERER), Barcelona, Spain. 86Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA. 146Center for Psychiatric Neuroscience, The Feinstein Institute of Medical Research, Manhasset, New York, USA. 195Department of Clinical Genetics, VU Medical Center, Amsterdam, The Netherlands. 224Clinical Psychology and Epidemiology, University of Basel, Basel, Switzerland. 230Neurosciences and Mental Health Program, Hospital for Sick Children, Toronto, Ontario Canada. 235BioFIG—Center for Biodiversity, Functional and Integrative Genomics, Campus da FCUL, Campo Grande, Lisbon, Portugal. 240Division of Genetics, Children’s Hospital Boston, Boston, Massachusetts, USA. 241Department of Neurology, Harvard Medical School Center for Life Sciences, Boston, Massachusetts, USA. URLs. PGC, https://pgc.unc.edu/; Genetic Cluster Computer, http://www.geneticcluster.org/; GCTA, http:// www.complextraitgenomics.com/software/gcta/. Note: Any Supplementary Information and Source Data files are available in the online version of the paper. AUTHOR CONTRIBUTIONS Project conception: K.S.K., N.R.W. and J.W.S. Analysis: S.H.L. and N.R.W. Writing of the manuscript: N.R.W., S.H.L., K.S.K. and S.V.F. Quality control for PGC data: S. Ripke and B.M.N. Revisions to the manuscript: S.M.P., J.W.S., R.H.P., B.J.M., P.F.S., A.T., C.O., M.J.D., R.D.O. and J.B. Statistical advice: M.E.G. and J.S.W. Data access: D.P. PGC Workgroup Chairs: M.J.D. (analysis), S.V.F. (ADHD), M.J.D. and B.D. (co-chairs ASD), J.K. and P. Sklar (co-chairs bipolar disorder), P.F.S. (major depressive disorder), M.C.O. (schizophrenia) and J.W.S. and K.S.K. (co-chairs cross-disorder group). Collection, genotyping and analysis for PGC Working Groups. PGC ADHD Working Group: B.M.N., S.V.F., A.T., R.A., P.A., T. Banaschewski, M. Bayés, J.B., J.K.B., M.C., B.C., J.C., A.E.D., R.P.E., J.E., B.F., C.M.F., L. Kent, J.K., K.-P.L., S.K.L., J.M., J.J.M., S.E.M., J.M.S., A. Miranda, S.F.N., R.D.O., J.A.R.-Q., A. Reif, M. Ribasés, H.R., A. Rothenberger, J.A.S., R.S., S.L. Smalley, E.J.S.S.-B., H.-C.S., A.A.T. and N.W. PGC ASD Working Group: R.A., D.E.A., A.J.B., A.B., C.B., J.D. Buxbaum, A. Chakravarti, E.H.C., H.C., M.L.C., G.D., E.D., S.E., E.F., C.M.F., L. Gallagher, D.H.G., M. Gill, D.E.G., J.L.H., H.H., J.H., V.H., S.M.K., L. Klei, D.H. Ledbetter, C. Lord, J.K.L., E.M., S.M.M., C.L.M., W.M.M., A.P.M., D.M.-D.-L., E.M.M., M. Murtha, G.O., A.P., J.R.P., A.D.P., M.A.P.-V., J. Piven, F.P., K. Rehnström, K. Roeder, G.R., S.J.S., S.L. Santangelo, G.D.S., S.W.S., M. State, J.S. Sutcliffe, P. Szatmari, A.M.V., V.J.V., C.A.W., T.H.W., E.M.W., A.J.W., T.W.Y., B.D. and M.J.D. PGC BPD Working Group: S.M.P., D.A., H.A., O.A.A., A.A., L.B., J.A.B., J.D. Barchas, T.B.B., N.B., M. Bauer, F.B., S.E.B., W.B., D.H.R.B., C.S.B., M. Boehnke, G.B., R. Breuer, W.E.B., W.F.B., S. Caesar, K. Chambert, S. Cichon, D.A.C., A. Corvin, W.H.C., D.W.C., R.D., F. Degenhardt, S. Djurovic, F. Dudbridge, H.J.E., B.E., A.E.F., I.N.F., M. Flickinger, T.F., J.F., C.F., L.F., E.S.G., M. Gill, K.G.-S., E.K.G., T.A.G., D.G., W.G., H.G., M.L.H., M. Hautzinger, S. Herms, M. Hipolito, P.A.H., C.M.H., S.J., E.G.J., I.J., L.J., R. Kandaswamy, J.L.K., G.K.K., D.L.K., P.K., M. Landén, N.L., M. Lathrop, J. Lawrence, W.B.L., M. Leboyer, P.H.L., J. Li, P.L., D.-Y.L., C. Liu, F.W.L., S.L., P.B.M., W.M., N.G.M., M. Mattheisen, K.M., M. Mattingsdal, K.A.M., P.M., M.G.M., A. McIntosh, R.M., A.W.M., F.J.M., A. McQuillin, S.M., I.M., F.M., G.W.M., J.L.M., G.M., D.W.M., V. Moskvina, P.M., T.W.M., W.J.M., B.M.-M., R.M.M., C.M.N., I.N., V.N., M.M.N., J.I.N., E.A.N., C.O., U.O., M.J.O., B.S.P., J.B.P., P.P., E.M.Q., S. Raychaudhuri, A. Reif, J.P.R., M. Rietschel, D. Ruderfer, M. Schalling, A.F.S., W.A.S., N.J.S., T.G.S., J. Schumacher, M. Schwarz, E.S., L.J.S., P.D.S., E.N.S., D.S.C., M. Steffens, J.S. Strauss, J. Strohmaier, S.S., R.C.T., F.T., J.T., J.B.V., S.J.W., T.F.W., S.H.W., W.X., A.H.Y., P.P.Z., P.Z., S. Zöllner, J.R.K., P. Sklar, M.J.D., M.C.O. and N.C. PGC MDD Working Group: M.R.B., T. Bettecken, E.B.B., D.H.R.B., D.I.B., G.B., R. Breuer, S. Cichon, W.H.C., I.W.C., D. Czamara, E.J.D.G., F. Degenhardt, A.E.F., J.F., S.D.G., M. Gross, S.P.H., A.C.H., A.K.H., S. Herms, I.B.H., F.H., W.J.H., S. Hoefels, J.-J.H., M.I., I.J., L.J., J.-Y. T., J.A.K., M.A.K., A.K., W.B.L., D.F.L., C.M.L., D.-Y.L., S.L., D.J.M., P.A.F.M., W.M.,. N.G.M., M. Mattheisen, P.J.M., P.M., A. McIntosh, A.W.M., C.M.M., L.M., G.W.M., P.M., B.M.-M., W.A.N., M.M.N., D.R.N., B.W.P., M.L.P., J.B.P., M. Rietschel, W.A.S., T.G.S., J. Shi, S.I.S., S.L. Slager, J.H.S., M. Steffens, F.T., J.T., M.U., E.J.C.G.v.d.O., G.V.G., M.M.W., G.W., F.G.Z., P.F.S. and N.R.W. PGC SCZ Working Group: S. Ripke, B.M.N., S.M.P., B.J.M., I.A., F.A., O.A.A., M.H.A., N.B., D.W.B., D.H.R.B., R. Bruggeman, N.G.B., W.F.B., W.C., R.M.C., K. Choudhury, S. Cichon, C.R.C., P.C., A. Corvin, D. Curtis, S. Datta, S. Djurovic, G.J.D., J.D., F. Dudbridge, A.F., R.F., N.B.F., M. Friedl, P.V.G., L. Georgieva, I.G., M. Gill, H.G., L.D.H., M.L.H., T.F.H., A.M.H., P.A.H., C.M.H., A.I., A.K.K, R.S.K., M.C.K., E.K., Y.K., G.K.K., B.K., L. Krabbendam, R. Krasucki, J. Lawrence, P.H.L., T.L., D.F.L., J.A.L., D.-Y.L., D.H. Linszen, P.K.E.M., W.M., A.K.M., M. Mattheisen, M. Mattingsdal, S.M., S.A.M., A. McIntosh, A. McQuillin, H.M., I.M., V. Milanova, D.W.M., V. Moskvina, I.M.-G., M.M.N., C.O., A.O., L.O., R.A.O., M.J.O., C.N.P., M.T.P., B.S.P., J. Pimm, D.P., V.P., D.J.Q., H.B.R., M. Rietschel, L.R., D. Ruderfer, D. Rujescu, A.R.S., T.G.S., J. Shi, J.M.S., D.S.C., T.S.S., S.T., J.V.O., P.M.V., T.W., S. Zammit, P. Sklar, M.J.D., M.C.O., N.C., P.F.S. and K.S.K. PGC Cross-Disorder Group Working Group: S.H.L., S. Ripke, B.M.N., S.M.P., R.H.P., A.T., A.F., M.C.N., J.I.N., B.W.P., M. Rietschel, T.G.S., N.C., S.L. Santangelo, P.F.S., J.W.S., K.S.K. and N.R.W. PGC Analysis Working Group: S.H.L., S. Ripke, B.M.N., S.M.P., V.A., E.M.B., P.H.L., S.E.M., M.C.N., D.P., M.J.D. and N.R.W. COMPETING FINANCIAL INTERESTS The authors declare no competing financial interests. Reprints and permissions informat