Genome-wide association study identifies five new schizophrenia loci

We examined the role of common genetic variation in schizophrenia in a genome-wide association study of substantial size: a stage 1 discovery sample of 21,856 individuals of European ancestry and a stage 2 replication sample of 29,839 independent subjects. The combined stage 1 and 2 analysis yielded genome-wide significant associations with schizophrenia for seven loci, five of which are new (1p21.3, 2q32.3, 8p23.2, 8q21.3 and 10q24.32-q24.33) and two of which have been previously implicated (6p21.32-p22.1 and 18q21.2). The strongest new finding (P = 1.6 × 10 -11) was with rs1625579 within an intron of a putative primary transcript for MIR137 (microRNA 137), a known regulator of neuronal development. Four other schizophrenia loci achieving genome-wide significance contain predicted targets of MIR137, suggesting MIR137-mediated dysregulation as a previously unknown etiologic mechanism in schizophrenia. In a joint analysis with a bipolar disorder sample (16,374 affected individuals and 14,044 controls), three loci reached genome-wide significance: CACNA1C (rs4765905, P = 7.0 × 10 -9), ANK3 (rs10994359, P = 2.5 × 10 -8) and the ITIH3-ITIH4 region (rs2239547, P = 7.8 × 10 -9).

Genome-wide study of familial juvenile hyperuricaemic (gouty) nephropathy (FJHN) indicates a new locus, FJHN3, linked to chromosome 2p22.1-p21

Familial juvenile hyperuricaemic (gouty) nephropathy (FJHN), is an autosomal dominant disease associated with a reduced fractional excretion of urate, and progressive renal failure. FJHN is genetically heterogeneous and due to mutations of three genes: uromodulin (UMOD), renin (REN) and hepatocyte nuclear factor-1beta (HNF-1β) on chromosomes 16p12, 1q32.1, and 17q12, respectively. However, UMOD, REN or HNF-1β mutations are found in only ~45% of FJHN probands, indicating the involvement of other genetic loci in ~55% of probands. To identify other FJHN loci, we performed a single nucleotide polymorphism (SNP)-based genome-wide linkage analysis, in six FJHN families in whom UMOD, HNF-1β and REN mutations had been excluded. Parametric linkage analysis using a 'rare dominant' model established linkage in five of the six FJHN families, with a LOD score >+3, at 0% recombination, between FJHN and SNPs at chromosome 2p22.1-p21. Analysis of individual recombinants in two unrelated affected individuals defined a ~5.5 Mbp interval, flanked telomerically by SNP RS372139 and centromerically by RS896986 that contained the locus, designated FJHN3. The interval contains 28 genes, and DNA sequence analysis of the most likely candidate, solute carrier family 8 member 1 (SLC8A1), did not identify any abnormalities in the FJHN3 probands. FJHN3 is likely located within a ~5.5 Mbp interval on chromosome 2p22.1-p21, and identifying the genetic abnormality will help to further elucidate mechanisms predisposing to gout and renal failure.

Crystal structures of the endoplasmic reticulum aminopeptidase-1 (ERAP1) reveal the molecular basis for N-terminal peptide trimming

Endoplasmatic reticulum aminopeptidase 1 (ERAP1) is a multifunctional enzyme involved in trimming of peptides to an optimal length for presentation by major histocompatibility complex (MHC) class I molecules. Polymorphisms in ERAP1 have been associated with chronic inflammatory diseases, including ankylosing spondylitis (AS) and psoriasis, and subsequent in vitro enzyme studies suggest distinct catalytic properties of ERAP1 variants. To understand structure-activity relationships of this enzyme we determined crystal structures in open and closed states of human ERAP1, which provide the first snapshots along a catalytic path. ERAP1 is a zinc-metallopeptidase with typical H-E-X-X-H-(X)18-E zinc binding and G-A-M-E-N motifs characteristic for members of the gluzincin protease family. The structures reveal extensive domain movements, including an active site closure as well as three different open conformations, thus providing insights into the catalytic cycle. A K 528R mutant strongly associated with AS in GWAS studies shows significantly altered peptide processing characteristics, which are possibly related to impaired interdomain interactions.

Identification of IL6R and chromosome 11q13.5 as risk loci for asthma

We aimed to identify novel genetic variants affecting asthma risk, since these might provide novel insights into molecular mechanisms underlying the disease. We did a genome-wide association study (GWAS) in 2669 physician-diagnosed asthmatics and 4528 controls from Australia. Seven loci were prioritised for replication after combining our results with those from the GABRIEL consortium (n=26 475), and these were tested in an additional 25 358 independent samples from four in-silico cohorts. Quantitative multi-marker scores of genetic load were constructed on the basis of results from the GABRIEL study and tested for association with asthma in our Australian GWAS dataset. Two loci were confirmed to associate with asthma risk in the replication cohorts and reached genome-wide significance in the combined analysis of all available studies (n=57 800): rs4129267 (OR 1·09, combined p= 2·4×10-8) in the interleukin-6 receptor (IL6R) gene and rs7130588 (OR 1·09, p=1·8×10-8) on chromosome 11q13.5 near the leucine-rich repeat containing 32 gene (LRRC32, also known as GARP). The 11q13.5 locus was significantly associated with atopic status among asthmatics (OR 1·33, p=7×10-4), suggesting that it is a risk factor for allergic but not non-allergic asthma. Multi-marker association results are consistent with a highly polygenic contribution to asthma risk, including loci with weak effects that might be shared with other immune-related diseases, such as NDFIP1, HLA-B, LPP, and BACH2. The IL6R association further supports the hypothesis that cytokine signalling dysregulation affects asthma risk, and raises the possibility that an IL6R antagonist (tocilizumab) may be effective to treat the disease, perhaps in a genotype-dependent manner. Results for the 11q13.5 locus suggest that it directly increases the risk of allergic sensitisation which, in turn, increases the risk of subsequent development of asthma. Larger or more functionally focused studies are needed to characterise the many loci with modest effects that remain to be identified for asthma. National Health and Medical Research Council of Australia. A full list of funding sources is provided in the webappendix. © 2011 Elsevier Ltd.

Interaction between ERAP1 and HLA-B27 in ankylosing spondylitis implicates peptide handling in the mechanism for HLA-B27 in disease susceptibility

Ankylosing spondylitis is a common form of inflammatory arthritis predominantly affecting the spine and pelvis that occurs in approximately 5 out of 1,000 adults of European descent. Here we report the identification of three variants in the RUNX3, LTBR-TNFRSF1A and IL12B regions convincingly associated with ankylosing spondylitis (P < 5 × 10-8 in the combined discovery and replication datasets) and a further four loci at PTGER4, TBKBP1, ANTXR2 and CARD9 that show strong association across all our datasets (P < 5 × 10-6 overall, with support in each of the three datasets studied). We also show that polymorphisms of ERAP1, which encodes an endoplasmic reticulum aminopeptidase involved in peptide trimming before HLA class I presentation, only affect ankylosing spondylitis risk in HLA-B27-positive individuals. These findings provide strong evidence that HLA-B27 operates in ankylosing spondylitis through a mechanism involving aberrant processing of antigenic peptides.

Genome-wide association study identifies susceptibility loci for open angle glaucoma at TMCO1 and CDKN2B-AS1

We report a genome-wide association study for open-angle glaucoma (OAG) blindness using a discovery cohort of 590 individuals with severe visual field loss (cases) and 3,956 controls. We identified associated loci at TMCO1 (rs4656461[G] odds ratio (OR) = 1.68, P = 6.1 × 10-10) and CDKN2B-AS1 (rs4977756[A] OR = 1.50, P = 4.7 × 10-9). We replicated these associations in an independent cohort of cases with advanced OAG (rs4656461 P = 0.010; rs4977756 P = 0.042) and two additional cohorts of less severe OAG (rs4656461 combined discovery and replication P = 6.00 × 10-14, OR = 1.51, 95% CI 1.35-1.68; rs4977756 combined P = 1.35 × 10-14, OR = 1.39, 95% CI 1.28-1.51). We show retinal expression of genes at both loci in human ocular tissues. We also show that CDKN2A and CDKN2B are upregulated in the retina of a rat model of glaucoma. © 2011 Nature America, Inc. All rights reserved.

Genetics and genomics of ankylosing spondylitis

Ankylosing spondylitis (AS) is a common, highly heritable arthropathy, the pathogenesis of which is poorly understood. The mechanism by which the main gene for the disease, HLA-B27, leads to AS is unknown. Genetic and genomic studies have demonstrated involvement of the interleukin-23 (IL-23) signaling pathway in AS, a finding which has stimulated much new research into the disease and has led to therapeutic trials. Several other genes and genetic regions, including further major histocompatibility complex (MHC) and non-MHC loci, have been shown to be involved in the disease, but it is not clear yet how they actually induce the condition. These findings have shown that there is a strong genetic overlap between AS and Crohn's disease in particular, although there are also major differences in the genes involved in the two conditions, presumably explaining their different presentations. Genomic and proteomic studies are in an early phase but have potential both as diagnostic/prognostic tools and as a further hypothesis-free tool to investigate AS pathogenesis. Given the slow progress in studying the mechanism of association of HLA-B27 with AS, these may prove to be more fruitful approaches to investigating the pathogenesis of the disease. © 2009 John Wiley & Sons A/S.

A genome-wide asociation study identifies new psoriasis susceptibility loci and an interaction betwEn HLA-C and ERAP1

To identify new susceptibility loci for psoriasis, we undertOk a genome-wide asociation study of 594,224 SNPs in 2,622 individuals with psoriasis and 5,667 controls. We identified asociations at eight previously unreported genomic loci. Seven loci harbored genes with recognized iMune functions (IL28RA, REL, IFIH1, ERAP1, TRAF3IP2, NFKBIA and TYK2). These asociations were replicated in 9,079 European samples (six loci with a combined P < 5-10 -8 and two loci with a combined P < 5-10-7). We also report compeLing evidence for an interaction betwEn the HLA-C and ERAP1 loci (combined P = 6.95-10-6). ERAP1 plays an important role in MHC claS I peptide proceSing. ERAP1 variants only influenced psoriasis susceptibility in individuals carrying the HLA-C risk aLele. Our findings implicate pathways that integrate epidermal barrier dysfunction with iNate and adaptive iMune dysregulation in psoriasis pathogenesis.