Schizophrenia (SCZ) is a severe mental disorder with a lifetime risk of about 1%, characterized by hallucinations, delusions and cognitive deficits with heritability estimated at up to 80%1,2. We adopted two analytic approaches to determine the extent to which common genetic variation underlies risk of SCZ using genome-wide association study (GWAS) data from 3,322 European individuals with SCZ and 3,587 controls. First, we implicate the major histocompatibility complex (MHC). Second, we provide molecular genetic evidence for a substantial polygenic component to risk of SCZ involving thousands of common alleles of very small effect. We show that this component also contributes to risk of bipolar disorder (BPD), but not to multiple non-psychiatric diseases.

We have derived a versatile gene-based test for genome-wide association studies (GWAS). Our approach, called VEGAS (versatile gene-based association study), is applicable to all GWAS designs, including family-based GWAS, meta-analyses of GWAS on the basis of summary data, and DNA-pooling-based GWAS, where existing approaches based on permutation are not possible, as well as singleton data, where they are. The test incorporates information from a full set of markers (or a defined subset) within a gene and accounts for linkage disequilibrium between markers by using simulations from the multivariate normal distribution. We show that for an association study using singletons, our approach produces results equivalent to those obtained via permutation in a fraction of the computation time. We demonstrate proof-of-principle by using the gene-based test to replicate several genes known to be associated on the basis of results from a family-based GWAS for height in 11,536 individuals and a DNA-pooling-based GWAS for melanoma in approximately 1300 cases and controls. Our method has the potential to identify novel associated genes; provide a basis for selecting SNPs for replication; and be directly used in network (pathway) approaches that require per-gene association test statistics. We have implemented the approach in both an easy-to-use web interface, which only requires the uploading of markers with their association p-values, and a separate downloadable application.

Cannabis use is a heritable trait that has been associated with adverse mental health outcomes. In the largest genome-wide association study (GWAS) for lifetime cannabis use to date (N = 184,765), we identified eight genome-wide significant independent single nucleotide polymorphisms in six regions. All measured genetic variants combined explained 11% of the variance. Gene-based tests revealed 35 significant genes in 16 regions, and S-PrediXcan analyses showed that 21 genes had different expression levels for cannabis users versus nonusers. The strongest finding across the different analyses was CADM2, which has been associated with substance use and risk-taking. Significant genetic correlations were found with 14 of 25 tested substance use and mental health-related traits, including smoking, alcohol use, schizophrenia and risk-taking. Mendelian randomization analysis showed evidence for a causal positive influence of schizophrenia risk on cannabis use. Overall, our study provides new insights into the etiology of cannabis use and its relation with mental health.

Refractive error is the most common eye disorder worldwide, and a prominent cause of blindness. Myopia affects over 30% of Western populations, and up to 80% of Asians. The CREAM consortium conducted genome-wide meta-analyses including 37,382 individuals from 27 studies of European ancestry, and 8,376 from 5 Asian cohorts. We identified 16 new loci for refractive error in subjects of European ancestry, of which 8 were shared with Asians. Combined analysis revealed 8 additional loci. The new loci include genes with functions in neurotransmission (GRIA4), ion channels (KCNQ5), retinoic acid metabolism (RDH5), extracellular matrix remodeling (LAMA2, BMP2), and eye development (SIX6, PRSS56). We also confirmed previously reported associations with GJD2 and RASGRF1. Risk score analysis using associated SNPs showed a tenfold increased risk of myopia for subjects with the highest genetic load. Our results, accumulated across independent multi-ethnic studies, considerably advance understanding of mechanisms involved in refractive error and myopia.

A genome-wide association study (GWAS) for open angle glaucoma (OAG) blindness was conducted using a discovery cohort of 590 cases with severe visual field loss and 3956 controls. Genome-wide significant associations were identified at TMCO1 (rs4656461 (G) OR=1.68, p=6.1x10 -10 ) and CDKN2B-AS1 (rs4977756 (A) OR = 1.50, p=4.7x10 -9 ). These findings were replicated in a second cohort of advanced OAG cases (rs4656461 p=0.010; rs4977756 p=0.042) and two further cohorts of less severe OAG. The study wide odds ratios are 1.51 (1.35-1.68), p=6.00x10 -14 at TMCO1, and 1.39 (1.28-1.51), p=1.35x10 -14 at CDKN2B-AS1 (also known as CDKN2BAS and ANRIL). Carriers of 1 or more risk alleles at both loci concurrently are at >3-fold increased risk of glaucoma. We demonstrate retinal expression of genes at both loci, and show that CDKN2A and CDKN2B are strongly upregulated in an animal model of glaucoma.Glaucoma is a group of neurodegenerative ocular diseases united by a clinically characteristic optic neuropathy. It is the second leading cause of blindness worldwide 1 . Primary open angle glaucoma (OAG) is the commonest subtype 1 . OAG pathogenesis and factors determining disease progression are poorly understood. Early intervention with measures to reduce intraocular pressure retards visual loss in most individuals 2 , but many cases of glaucoma remain undiagnosed until irreversible vision loss has occurred. Elucidation of SNPs associated with severe outcomes could enable better targeting of treatments which carry cost and morbidity, to individuals at highest risk of blindness. Linkage and candidate gene studies have identified several genes likely to be involved in OAG including myocilin 3 and NTF4 4 , although for the latter, findings have varied in different populations 5 . A recent GWAS using Icelandic OAG cases of unselected severity identified association with variants near CAV1 6 . To identify genes predisposing individuals to OAG blindness, we performed a GWAS in Australian Caucasians with advanced OAG (individuals with OAG who have progressed to severe visual field loss or blindness).