Proxy Single-nucleotide Polymorphisms Research Articles

The causal effect of inflammatory bowel disease on diffuse large B-cell lymphoma: two-sample Mendelian randomization study.

It has been reported that inflammatory bowel disease (IBD) is associated with an increased risk of malignancies, including lymphoma. A number of large observational studies have been devoted to exploring the causal link between IBD and malignant lymphoma. However, no consensus exists on whether there is a causal relationship between IBD and malignant lymphoma. The summary dataset of the IBD and lymphoma genome-wide association studies (GWAS) was obtained from the OPEN GWAS website. Single-nucleotide polymorphisms (SNPs) were selected as genetic instrumental variants (IVs) for fulling P < 5 × 10-8 and linkage disequilibrium (LD) of r2 = 0.001 in the IBD GWAS. The proxy SNPs with LD of r2 > 0.8 were identified. Palindromic SNPs and outlier SNPs were excluded. The assessments of sensitivity employed the Cochran's Q test, Mendelian randomization (MR)-Egger intercept test, and leave-one-out analysis. The MR analysis results proved the causality of IBD on diffuse large B-cell lymphoma (DLBCL). The risk of developing DLBCL is increased by 28.6% in patients with IBD [odds ratio (OR)IVW = 1.286, 95% confidence interval (CI) 1.066-1.552, P = 0.009]. The results of the subgroup analysis showed that Crohn's disease (ORIVW = 1.218, 95% CI 1.030-1.441, P = 0.021) rather than ulcerative colitis (ORIVW = 1.206, 95% CI 0.984-1.478, P = 0.072) had a causal effect on DLBCL. No horizontal and directional pleiotropy was observed in the MR studies. The above MR study concluded that IBD itself is causally responsible for DLBCL, especially Crohn's disease. Further investigations are needed to elucidate the mechanism underlying this direct causal link.

THE ASSOCIATION BETWEEN BLOOD PRESSURE VARIABILITY AND DEMENTIA: A TWO-SAMPLE MENDELIAN RANDOMIZATION STUDY

Objective: This study aims to investigate the causal inference by applying a mendelian randomization (MR) study using single-nucleotide polymorphisms (SNPs) from the genome-wide association study (GWAS) based on the UK biobank. Design and method: The genetic instruments were chosen from BPV GWAS based on UK Biobank data. Four GWA studies were used for the genetic evaluation of dementia, including (1) The International Genomic of Alzheimer's Project (IGAP) GWAS for dementia; (2) and (3) UK Biobank GWAS for proxy phenotypes of Alzheimer's dementia: the maternal and paternal family history (MFH and PFH-UKBB); (4) A combined GWAS meta-analysis from the abovementioned three GWAS results. The following exclusion criteria were applied for SNPs: (1) confounding SNPs by searching hypertension and artery stiffness GWAS; (2) significant SNPs that are associated with dementia in the datasets; (3) palindromic SNPs with an effect allele frequency between 0.4 and 0.7. Proxy SNPs were manually selected for some SNPs. (4) only SNPs with linkage disequilibrium r2 &lt; 0.01 were selected as genetic instruments, also known as independent SNPs. The effect/reference alleles were checked to ensure the consistency of the base pair between BPV and dementia GWAS, which is also known as data harmonization. After data harmonization, four MR methods were employed to measure the causal effect: IVW-MR with random effect, IVW-MR with fixed effect, MR-Egger, and weighted median MR. Results: Finally, six independent SNPs were chosen as instrument variants for SBPV, and five for DBPV. Significant causal effects of SBPV on dementia were found in the PFH-UKBB dataset, and the odds ratio of dementia per 10-unit increase in SBPV was 1.028, 1.015, and 1.015 for MR-Egger, weighted median, and IVW-MR, respectively (Table 1). In contrast, only one significant result was found for DBPV in MFH-UKBB. No significant results were found on other datasets. Conclusions: Along with the evidence from different observational studies, this GWAS study demonstrates that systolic blood pressure variability is a potential causal risk factor for Alzheimer's dementia, while the evidence from diastolic blood pressure variability is still uncertain.

Genetically predicted adipose tissue distribution influences the risk of atherosclerosis.

Truncal obesity is a key modifiable risk factor in cardiovascular disease (CVD). It is a highly complex phenotype, and numerous factors such as the distribution of adipose tissue may influence risk of CVD.1 However, while some studies have suggested that gluteofemoral fat deposits may serve a protective role, others have offered conflicting results.2,3 As observational studies may be vulnerable to confounding from environmental factors, we conducted a Mendelian randomization study investigating the effect of regional adipose tissue distribution on the risk of different types of atherosclerosis and heart failure (HF). The Mendelian randomization approach leverages genetic variation to infer causal associations as genetic variants in the human genome are inherited randomly, independently of environmental factors.4 All data used in this study were publicly available. First, we obtained summary statistics from a recent genome-wide association study on visceral adipose tissue (VAT), abdominal subcutaneous adipose tissue (AAT), and gluteofemoral adipose tissue (GFAT).5 Adipose tissue traits were determined by magnetic resonance imaging (MRI) of up to 39 076 individuals from the UK Biobank and were adjusted for age, sex, BMI, height, and 10 principal components. Instrument variables were selected from single-nucleotide polymorphisms (SNPs) that were robustly associated with the traits on a genome-wide significant level (P < 5 × 10−8). Instrument variables were pruned for linkage disequilibrium (LD), using a 10 megabase (Mb) window. For genetically correlated variants (R2 > 0.001), the variant with the smallest P-value was selected. We considered myocardial infarction (MI), large artery atherosclerotic stroke (LAS), and peripheral artery disease (PAD) as proxies for atherosclerosis. We acquired MI and LAS summary statistics from the CARDIoGRAMplusC4D consortium6 and the European subset of the GIGASTROKE consortium.7 Summary statistics for PAD and HF were obtained from the FinnGen study.8 There was no sample overlap between exposure and outcome datasets. For instrument variables not present in the outcome datasets, we identified suitable proxy SNPs in LD (r2 > 0.8).

The association of alanine aminotransferase and diabetic microvascular complications: A Mendelian randomization study.

Alanine aminotransferase (ALT) is positively related to diabetes risk in observational studies, whereas Mendelian randomization supports a linear causal association. In contrast, the relationship between ALT and diabetic nephropathy, and diabetic retinopathy is counter-intuitive in observational studies. Furthermore, no MR study has examined their causal association. The study aimed to investigate whether genetically determined ALT has a causal effect on diabetic nephropathy and diabetic retinopathy. Genetic instruments associated with ALT (P < 5×10-8) were obtained from a recent genome-wide association study (GWAS) that included 437,267 individuals of European ancestry. Summary data of diabetic microvascular complications were derived from the FinnGen study (3,283 cases and 181,704 controls for diabetic nephropathy, and 14,584 cases and 176,010 controls for diabetic retinopathy, both were of European ancestry). Effect estimation and pleiotropy testing were performed using inverse variance weighted (IVW), MR-Egger regression, weighted median, and mode-based estimator methods. We additionally performed sensitivity analysis excluding proxy single nucleotide polymorphisms (SNPs) or lowering the GWAS significance threshold (P < 5×10-7) to test the robustness of the results. Based on IVW, a 2-fold increase in genetically determined ALT level was positively associated with diabetic nephropathy (odd ratio, [95% confidence interval], 1.73 [1.26-2.37], P = 0.001) and diabetic retinopathy (1.29 [1.08-1.54], P = 0.005), but a null causal association in three pleiotropy robust methods, namely, MR-Egger, weighted median and mode-based estimator. We obtained similar results in the sensitivity analysis of excluding proxy SNPs or lowering the GWAS significance threshold. With caution, we concluded that ALT plays no linear causal role in developing both diabetic nephropathy and diabetic retinopathy. Further investigations are required to test the hypothesis of a non-linear causal association.

Sex Hormone Candidate Gene Polymorphisms Are Associated with Endometriosis.

The present study was designed to examine whether sex hormone polymorphisms proven by GWAS are associated with endometriosis risk. Unrelated female participants totaling 1376 in number (395 endometriosis patients and 981 controls) were recruited into the study. Nine single-nucleotide polymorphisms (SNPs) which GWAS correlated with circulating levels of sex hormones were genotyped using a TaqMan allelic discrimination assay. FSH-lowering, and LH- and testosterone-heightening polymorphisms of the FSHB promoter (allelic variants A rs11031002 and C rs11031005) exhibit a protective effect for endometriosis (OR = 0.60-0.68). By contrast, the TT haplotype loci that were GWAS correlated with higher FSH levels and lower LH and testosterone concentrations determined an increased risk for endometriosis (OR = 2.03). Endometriosis-involved epistatic interactions were found between eight loci of sex hormone genes (without rs148982377 ZNF789) within twelve genetic simulation models. In silico examination established that 8 disorder-related loci and 80 proxy SNPs are genome variants affecting the expression, splicing, epigenetic and amino acid conformation of the 34 genes which enrich the organic anion transport and secondary carrier transporter pathways. In conclusion, the present study showed that sex hormone polymorphisms proven by GWAS are associated with endometriosis risk and involved in the molecular pathophysiology of the disease due to their functionality.

Association between central serous chorioretinopathy susceptibility genes and choroidal parameters.

To evaluate the association between central serous chorioretinopathy (CSC) susceptibility genes and choroidal parameters in a large Japanese cohort. Retrospective cohort study. Of the 9850 individuals in the Nagahama study whose second visit was between 2013 and 2016, those with optical coherence tomography (OCT) images with enhanced depth imaging (EDI), axial length, and genome-wide single nucleotide polymorphism (SNP) genotyping data were included. We calculated subfoveal choroidal thickness (SFCT), choroidal vascularity index (CVI), normalized choroidal intensity (NCI), and vertical asymmetry of choroidal thickness. Genome-wide quantitative trait locus (QTL) analyses were performed for each parameter. We screened for four CSC susceptibility SNPs: CFH rs800292, TNFRSF10A rs13278062, GATA5 rs6061548, and VIPR2 rs3793217. Whenever an SNP was not included in the genotyping data after quality control, its proxy SNP was selected. In total, 4586 participants were evaluated. CFH rs800292 was significantly associated with SFCT (P < 0.001) and CVI (P < 0.001). VIPR2 rs3793217 was significantly associated with SFCT (P < 0.001) but not with CVI. Whereas, TNFRSF10A rs13254617 and GATA5 rs6061548 were not significantly associated with SFCT or CVI. None of these SNPs was associated with NCIEDI and asymmetry of choroidal thickness. CFH, VIPR2, TNFRSF10A, and GATA5 showed different association patterns with choroidal parameters. Although the mechanism of CSC pathogenesis by choroidal changes is not fully understood, this finding suggests that each gene may be involved in different mechanisms of CSC development. Our genetic study provides a basis for understanding the role of CSC susceptibility genes.

188-LB: Deep Learning–Based Population Screening of Type 1 Diabetes and Celiac Disease Genetic Risk from Blood Spots at Birth

Introduction: Screening for type 1 diabetes (T1D) genetic risk in early life can prevent life threatening complications such as diabetic ketoacidosis and allow cost-effective recruitment into intervention and immunotherapy trials. Celiac disease (CD) frequently presents as a comorbidity in those with T1D and shares a strong genetic basis with T1D. Single nucleotide polymorphism (SNP) based genetic risk scores (GRS) for both T1D and CD have shown to be very predictive of future disease but are difficult to generate and typically require SNP array genotyping. We aimed to develop a combined GRS screening panel that could be genotyped from a single dried blood spot at birth. Methods: We developed assays for proxy SNPs of common HLA-DQ haplotypes reported in previous GRS and additional loci from the most recent available genome-wide association studies (GWAS) . We used backwards stepwise regression to identify a subset of variants able to be genotyped with DNA eluted from 800 6mm dried blood spots. We developed and validated neural network models to quantify genetic risk of both T1D and CD using T1DGC and UK Celiac case-control SNP array data, validated in UK Biobank. Assays were developed with LGC Genomics and validated on 675 Seattle area samples. Results: The complete panel consisted of 71 validated SNP assays, including 11 backup variants for key loci. We generated neural nework models which demonstrate equivalent or greater predictive power (AUC: T1D=0.914, CD=0.893) to previously published GRS yet require much less expertise to apply. We have developed an algorithm for preparation of raw genotyping data and subsequent generation of GRS requiring little expertise to apply. Conclusion: A 71 SNP blood-spot screening panel is highly effective at screening genetic risk associated with T1D and CD at birth. Using a neural network model the panel enables widely available, easy to generate and inexpensive population screening of genetic risk for T1D and CD. Disclosure S. A. Sharp: None. J. M. Locke: None. Y. Xu: None. D. P. Fraser: None. L. A. Ferrat: None. M. N. Weedon: None. M. Inouye: None. R. A. Oram: Consultant; Janssen Research &amp; Development, LLC, Research Support; Randox R &amp; D. W. Hagopian: Research Support; Janssen Research &amp; Development, LLC. Funding Diabetes UK (16/0005529) JDRF (3-SRA-2019-827-S-B)

Genome-Wide Analysis of Sex Disparities in the Genetic Architecture of Lung and Colorectal Cancers.

Almost all complex disorders have manifested epidemiological and clinical sex disparities which might partially arise from sex-specific genetic mechanisms. Addressing such differences can be important from a precision medicine perspective which aims to make medical interventions more personalized and effective. We investigated sex-specific genetic associations with colorectal (CRCa) and lung (LCa) cancers using genome-wide single-nucleotide polymorphisms (SNPs) data from three independent datasets. The genome-wide association analyses revealed that 33 SNPs were associated with CRCa/LCa at P < 5.0 × 10−6 neither males or females. Of these, 26 SNPs had sex-specific effects as their effect sizes were statistically different between the two sexes at a Bonferroni-adjusted significance level of 0.0015. None had proxy SNPs within their ±1 Mb regions and the closest genes to 32 SNPs were not previously associated with the corresponding cancers. The pathway enrichment analyses demonstrated the associations of 35 pathways with CRCa or LCa which were mostly implicated in immune system responses, cell cycle, and chromosome stability. The significant pathways were mostly enriched in either males or females. Our findings provided novel insights into the potential sex-specific genetic heterogeneity of CRCa and LCa at SNP and pathway levels.

Integrative analysis of liver-specific non-coding regulatory SNPs associated with the risk of coronary artery disease

Genetic factors underlying coronary artery disease (CAD) have been widely studied using genome-wide association studies (GWASs). However, the functional understanding of the CAD loci has been limited by the fact that a majority of GWAS variants are located within non-coding regions with no functional role. High cholesterol and dysregulation of the liver metabolism such as non-alcoholic fatty liver disease confer an increased risk of CAD. Here, we studied the function of non-coding single-nucleotide polymorphisms in CAD GWAS loci located within liver-specific enhancer elements by identifying their potential target genes using liver cis-eQTL analysis and promoter Capture Hi-C in HepG2 cells. Altogether, 734 target genes were identified of which 121 exhibited correlations to liver-related traits. To identify potentially causal regulatory SNPs, the allele-specific enhancer activity was analyzed by (1) sequence-based computational predictions, (2) quantification of allele-specific transcription factor binding, and (3) STARR-seq massively parallel reporter assay. Altogether, our analysis identified 1,277 unique SNPs that display allele-specific regulatory activity. Among these, susceptibility enhancers near important cholesterol homeostasis genes (APOB, APOC1, APOE, and LIPA) were identified, suggesting that altered gene regulatory activity could represent another way by which genetic variation regulates serum lipoprotein levels. Using CRISPR-based perturbation, we demonstrate how the deletion/activation of a single enhancer leads to changes in the expression of many target genes located in a shared chromatin interaction domain. Our integrative genomics approach represents a comprehensive effort in identifying putative causal regulatory regions and target genes that could predispose to clinical manifestation of CAD by affecting liver function.

High‐resolution, genome‐wide, promoter‐focused Capture C in astrocytes implicates causal genes for Alzheimer’s disease

AbstractBackgroundPrevious studies of Alzheimer’s Disease (AD) have primarily implicated neurons and microglia as disease‐conferring cell types due to obvious links with degeneration and inflammation, respectively. However, astrocytes may also play a role in AD pathogenesis, but have been less studied in this context. Indeed, genome‐wide association studies (GWAS) have identified multiple genomic variants that reside near genes with astrocyte‐related functions, such as lipid processing and synaptic function. However, GWAS only reports genomic variants associated with a given trait and not necessarily the precise localization of culprit genes. High resolution chromatin conformation capture‐based techniques detect 3D genomic interactions between GWAS‐implicated signals and their effector genes, and allow for the characterization of non‐coding variants in the context of their regulatory activity.MethodTo improve on the low resolution of available Hi‐C data, we employed a high resolution DpnII‐based Capture‐C method to simultaneously characterize the physical genome‐wide interactions of 36,691 baited regions covering human promoters genome‐wide (including non‐coding transcripts) ‐ which we applied to a human primary astrocyte line (NHA, Lonza). Following sequencing, we investigated significant interactions at two different resolutions (1‐fragment and 4‐fragment resolutions; median fragment size = 265bp and 1,441bp, respectively). In parallel, we generated ATAC‐seq open chromatin maps to filter for informative (r2&gt;0.7) proxy single nucleotide polymorphisms (SNPs) for each of the 45 AD independent signals reported to date.ResultATAC‐seq fine‐mapping yielded 100 candidate SNPs in open chromatin for 30 of these loci. By further constraining on our promoter Capture C data in astrocytes, at both one and four DpnII fragment resolution (median distance between interacting regions 9kb and 71kb, respectively), we observed contacts to “open” promoters for 6 putative target genes, corresponding to 6 of the original GWAS loci. These included PICALM, FERMT2, CASS4, and CLU. ConclusionWe observed informative contacts between proxy SNPs and putative effector genes in the human astrocyte context for ∼13% of AD GWAS loci. Further efforts in other relevant cell types, where many of the other loci may in fact be principally operating, should shed light on additional signals. Follow‐up functional studies are warranted to validate these findings.

Serum Uric Acid Level and Multiple Sclerosis: A Mendelian Randomization Study.

Previous observational studies have shown that the serum uric acid (UA) level is decreased in persons with multiple sclerosis (MS). We used the two-sample Mendelian randomization (MR) method to determine whether the serum UA level is causally associated with the risk of MS. We screened 26 single-nucleotide polymorphisms (SNPs) in association with serum UA level (p < 5 × 10–8) from a large genome-wide meta-analysis involving 110,347 individuals. The SNP outcome effects were obtained from two large international genetic studies of MS involving 38,589 individuals and 27,148 individuals. A total of 18 SNPs, including nine proxy SNPs, were included in the MR analysis. The estimate based on SNP rs12498742 that explained the largest proportion of variance showed that the odds ratio (OR) of UA (per mg/dl increase) for MS was 1.00 [95% confidence interval (CI) 0.90–1.11; p = 0.96]. The main MR analysis based on the random effects inverse variance weighted method showed that the pooled OR was 1.05 (95% CI 0.92–1.19; p = 0.50). Although there was no evidence of net horizontal pleiotropy in MR-Egger regression (p = 0.48), excessive heterogeneity was found via Cochran’s Q statistic (p = 9.6 × 10–4). The heterogeneity showed a substantial decrease after exclusion of two outlier SNPs (p = 0.17). The pooled ORs for the other MR methods ranged from 0.89 (95% CI 0.65–1.20; p = 0.45) to 1.05 (95% CI 0.96–1.14; p = 0.29). The results of sensitivity analyses and additional analyses all showed similar pooled estimates. MR analyses by using 81 MS -associated SNPs as instrumental variables showed that genetically predicted risk of MS was not significantly associated with serum UA level. The pooled OR was 1.00 (95% CI 0.99–1.02; p = 0.74) for the main MR analysis. This MR study does not support a causal effect of genetically determined serum UA level on the risk of MS, nor does it support a causal effect of genetically determined risk of MS on serum UA level.

HIGH-RESOLUTION GENOMEWIDE PROMOTER-FOCUSED CONNECTOME IMPLICATES MICROGLIA CAUSAL GENES FOR ALZHEIMER’S DISEASE

Microglia are implicated as playing a central role in the pathogenesis of Alzheimer's Disease (AD). Indeed, genome-wide association studies (GWAS) have identified multiple genomic variants associated with inflammation and microglial immune response. That said, GWAS reports genomic signals associated with a given trait and not necessarily the precise localization of culprit effector genes. High resolution chromatin conformation capture-based techniques that detect contacts between distant regions of the genome offer a valuable tool to understand GWAS signals that reside almost exclusively in non-coding regions, principally through their presumed influence on regulatory elements. To improve on the low resolution of available Hi-C data, we expanded a high resolution Capture-C based method to simultaneously characterize the physical genome-wide interactions of all human promoters - which we applied to the human microglial cell line, HMC3. A custom Agilent SureSelect library was designed to target both ends of DpnII restriction fragments that overlap promoters of both protein-coding and noncoding transcripts, totaling 36,691 RNA baited fragments. Following sequencing, we investigated significant interactions at different resolutions. In parallel, we generated ATAC-seq open chromatin maps to filter for informative proxy (using a liberal r2>0.4) single nucleotide polymorphisms (SNPs) for each of 38 AD common independent sentinel SNPs reported to date beyond the APOE locus. ATAC-seq fine-mapping yielded 43 candidate SNPs in open chromatin for 14 of these loci. By further constraining on our promoter connectome data in HMC3 cells, at both one and four DpnII fragment resolution (median distance between interacting regions 24kb and 122kb, respectively; median region size = 265bp and 1,441bp, respectively), we observed contacts to “open” promoters for 12 putative target genes, relevant to four of the original GWAS loci. These included RTFDC1 at the ‘CASS4’ locus and MADD and PACSIN3 at the ‘CELF1’ locus. We observed informative contacts between proxy SNPs and putative effector genes for ∼11% of AD GWAS loci in the human microglia-specific context. Further efforts in other relevant cell types, where many of the other loci may in fact be principally operating, should shed light on additional signals. Follow-up functional studies are warranted to validate these findings.

ITPKB and ZNF184 are associated with Parkinson's disease risk in East Asians

A recent meta-analysis of Parkinson's disease (PD) genome-wide association studies has identified 17 novel risk loci in the European population. We aim to assess if these reported novel risk loci are similarly implicated in PD risk within the East Asian population by analyzing the reported risk single nucleotide polymorphism or proxy single nucleotide polymorphism in 14,006 East Asian samples (779 patients and 13,227 controls). We found that 9 of the 17 reported novel PD risk loci showed very similar effects in Europeans and East Asians (I2 = 0 to 10.7%), of which 2 loci ITPKB and ZNF184 were significantly associated with PD in our samples. Two of the reported risk loci, ANK2/CAMK2D and CTSB, were non-polymorphic in East Asians and therefore not implicated in PD risk in the East Asian population. Given the small effect sizes of these risk loci, further validation is needed in additional Asian samples.

Downstream TRPM4 Polymorphisms Are Associated with Intracranial Hypertension and Statistically Interact with ABCC8 Polymorphisms in a Prospective Cohort of Severe Traumatic Brain Injury.

Sulfonylurea-receptor-1(SUR1) and its associated transient-receptor-potential cation channel subfamily-M (TRPM4) channel are key contributors to cerebral edema and intracranial hypertension in traumatic brain injury (TBI) and other neurological disorders. Channel inhibition by glyburide is clinically promising. ABCC8 (encoding SUR1) single-nucleotide polymorphisms (SNPs) are reported as predictors of raised intracranial pressure (ICP). This project evaluated whether TRPM4 SNPs predicted ICP and TBI outcome. DNA was extracted from 435 consecutively enrolled severe TBI patients. Without a priori selection, all 11 TRPM4 SNPs available on the multiplex platform (Illumina:Human-Core-Exome v1.0) were genotyped spanning the 25 exon gene. A total of 385 patients were analyzed after quality control. Outcomes included ICP and 6 month Glasgow Outcome Scale (GOS) score. Proxy SNPs, spatial modeling, and functional predictions were determined using established software programs. rs8104571 (intron-20) and rs150391806 (exon-24) were predictors of ICP. rs8104571 heterozygotes predicted higher average ICP (β = 10.3 mm Hg, p = 0.00000029), peak ICP (β = 19.6 mm Hg, p = 0.0007), and proportion ICP >25 mm Hg (β = 0.16 p = 0.004). rs150391806 heterozygotes had higher mean (β = 7.2 mm Hg, p = 0.042) and peak (β = 28.9 mm Hg, p = 0.0015) ICPs. rs8104571, rs150391806, and 34 associated proxy SNPs in linkage-disequilibrium clustered downstream. This region encodes TRPM4's channel pore and a region postulated to juxtapose SUR1 sequences encoded by an ABCC8 DNA segment containing previously identified relevant SNPs. There was an interaction effect on ICP between rs8104571 and a cluster of predictive ABCC8 SNPs (rs2237982, rs2283261, rs11024286). Although not significant in univariable or a basic multivariable model, in an expanded model additionally accounting for injury pattern, computed tomographic (CT) appearance, and intracranial hypertension, heterozygous rs8104571 was associated with favorable 6 month GOS (odds ratio [OR] = 16.7, p = 0.007951). This trend persisted in a survivor-only subcohort (OR = 20.67, p = 0.0168). In this cohort, two TRPM4 SNPs predicted increased ICP with large effect sizes. Both clustered downstream, spanning a region encoding the channel pore and interacting with SUR1. If validated, this may guide risk stratification and eventually inform treatment-responder classification for SUR1-TRPM4 inhibition in TBI. Larger studies are warranted.

Comprehensive identification of pleiotropic loci for body fat distribution using the NHGRI-EBI Catalog of published genome-wide association studies.

We conducted a hypothesis-free cross-trait analysis for waist-to-hip ratio adjusted for body mass index (WHRadjBMI ) loci derived through genome-wide association studies (GWAS). Summary statistics from published GWAS were used to capture all WHRadjBMI single-nucleotide polymorphisms (SNPs), and their proxy SNPs were identified. These SNPs were used to extract cross-trait associations between WHRadjBMI SNPs and other traits through the NHGRI-EBI GWAS Catalog. Pathway analysis was conducted for pleiotropic WHRadjBMI SNPs. We found 160 WHRadjBMI SNPs and 3675 proxy SNPs. Cross-trait analysis identified 239 associations, of which 100 were for obesity traits. The remaining 139 associations were filtered down to 101 unique linkage disequilibrium block associations, which were grouped into 13 categories: lipids, red blood cell traits, white blood cell counts, inflammatory markers and autoimmune diseases, type 2 diabetes-related traits, adiponectin, cancers, blood pressure, height, neuropsychiatric disorders, electrocardiography changes, urea measurement, and others. The highest number of cross-trait associations were found for triglycerides (n=10), high-density lipoprotein cholesterol (n=9), and reticulocyte counts (n=8). Pathway analysis for WHRadjBMI pleiotropic SNPs found immune function pathways as the top canonical pathways. Results from our original methodology indicate a novel genetic association between WHRadjBMI and reticulocyte counts and highlight the pleiotropy between abdominal obesity, immune pathways, and other traits.

Missing single nucleotide polymorphisms in Genetic Risk Scores: A simulation study.

Using a genetic risk score (GRS) to predict a phenotype in a target sample can be complicated by missing data on the single nucleotide polymorphisms (SNPs) that comprise the GRS. This is usually addressed by imputation, omission of the SNPs or by replacing the missing SNPs with proxy SNPs. To assess the impact of the omission and proxy approaches on effect size estimation and predictive ability of weighted and unweighted GRS with small numbers of SNPs, we simulated a dichotomous phenotype conditional on real genotype data. We considered scenarios in which the proportion of missing SNPs ranged from 20–70%. We assessed the impact of omitting or replacing missing SNPs on the association between the GRS and phenotype, the corresponding statistical power and the area under the receiver operating curve. Omission resulted in a larger bias towards the null value of the effect size, a smaller predictive ability and greater loss of statistical power than proxy approaches. The predictive ability of a weighted GRS that includes SNPs with large weights depends of the availability of these large-weight SNPs.

Data integration for functional annotation of regulatory single nucleotide polymorphisms associated with Alzheimer's disease susceptibility

BackgroundAlzheimer's disease (AD), the most common form of dementia affects 24.3 million people worldwide. More than twenty genetic loci have been associated with AD and a significant number of genetic variants were mapped within these loci. A large proportion of genome wide significant variants lie outside the coding region. However, the plausible function of these variants is still unexplored. ObjectiveThe present study aimed to unravel the regulatory role of proxy single nucleotide polymorphisms (SNPs), to determine their risk of developing AD. MethodsThe RegulomeDB was employed to predict the regulatory role of proxy SNPs. Protein association network and functional enrichment analysis was performed using String10.5 and gene ontology, respectively. ResultsA total of 451 SNPs were examined through SNAP web portal (r2 ≤ 0.80) which returned 2186 proxy SNPs in linkage disequilibrium (LD) with genome wide significant SNPs for AD. Out of 2186 SNPs analyzed in RegulomeDB, 151 had the scores < 3 that indicates the high degree of their potential regulatory function. Further analysis revealed that out of these 151 SNPs, 37 were genome wide significant for AD, 17 were significantly associated with diseases other than AD, 89 were proxy SNPs (not genome wide significant) for various diseases including AD while 8 SNPs were novel proxy SNPs for AD. ConclusionThese findings support the notion that the non-coding variants can be strongly associated with disease risk. Further validation through genome wide association studies will be helpful for the elucidation of their regulatory potential.

Regionally clustered ABCC8 polymorphisms in a prospective cohort predict cerebral oedema and outcome in severe traumatic brain injury

ObjectiveABCC8 encodes sulfonylurea receptor 1, a key regulatory protein of cerebral oedema in many neurological disorders including traumatic brain injury (TBI). Sulfonylurea-receptor-1 inhibition has been promising in ameliorating cerebral oedema...

Genetic Variants Influencing Plasma Renin Activity in Hypertensive Patients From the PEAR Study (Pharmacogenomic Evaluation of Antihypertensive Responses).

Plasma renin is an important regulator of blood pressure (BP). Plasma renin activity (PRA) has been shown to correlate with variability in BP response to antihypertensive agents. We conducted a genome-wide association study to identify single-nucleotide polymorphisms (SNPs) associated with baseline PRA using data from the PEAR study (Pharmacogenomic Evaluation of Antihypertensive Responses). Multiple linear regression analysis was performed in 461 whites and 297 blacks using an additive model, adjusting for age, sex, and ancestry-specific principal components. Top SNPs were prioritized by testing the expected direction of association for BP response to atenolol and hydrochlorothiazide. Top regions from the BP response prioritization were tested for functional evidence through differences in gene expression by genotype using RNA sequencing data. Regions with functional evidence were assessed for replication with baseline PRA in an independent study (PEAR-2). Our top SNP rs3784921 was in the SNN-TXNDC11 gene region. The G allele of rs3784921 was associated with higher baseline PRA (β=0.47; P=2.09×10-6) and smaller systolic BP reduction in response to hydrochlorothiazide (β=2.97; 1-sided P=0.006). In addition, TXNDC11 expression differed by rs3784921 genotype (P=0.007), and rs1802409, a proxy SNP for rs3784921 (r2=0.98-1.00), replicated in PEAR-2 (β=0.15; 1-sided P=0.038). Additional SNPs associated with baseline PRA that passed BP response prioritization were in/near the genes CHD9, XIRP2, and GHR. CONCLUSIONS: We identified multiple regions associated with baseline PRA that were prioritized through BP response signals to 2 mechanistically different antihypertensive drugs. URL: https://www.clinicaltrials.gov. Unique identifier: NCT00246519.

Genome-wide pleiotropy analysis of neuropathological traits related to Alzheimer\u2019s disease

BackgroundSimultaneous consideration of two neuropathological traits related to Alzheimer’s disease (AD) has not been attempted in a genome-wide association study.MethodsWe conducted genome-wide pleiotropy analyses using association summary statistics from the Beecham et al. study (PLoS Genet 10:e1004606, 2014) for AD-related neuropathological traits, including neuritic plaque (NP), neurofibrillary tangle (NFT), and cerebral amyloid angiopathy (CAA). Significant findings were further examined by expression quantitative trait locus and differentially expressed gene analyses in AD vs. control brains using gene expression data.ResultsGenome-wide significant pleiotropic associations were observed for the joint model of NP and NFT (NP + NFT) with the single-nucleotide polymorphism (SNP) rs34487851 upstream of C2orf40 (alias ECRG4, P = 2.4 × 10−8) and for the joint model of NFT and CAA (NFT + CAA) with the HDAC9 SNP rs79524815 (P = 1.1 × 10−8). Gene-based testing revealed study-wide significant associations (P ≤ 2.0 × 10−6) for the NFT + CAA outcome with adjacent genes TRAPPC12, TRAPPC12-AS1, and ADI1. Risk alleles of proxy SNPs for rs79524815 were associated with significantly lower expression of HDAC9 in the brain (P = 3.0 × 10−3), and HDAC9 was significantly downregulated in subjects with AD compared with control subjects in the prefrontal (P = 7.9 × 10−3) and visual (P = 5.6 × 10−4) cortices.ConclusionsOur findings suggest that pleiotropy analysis is a useful approach to identifying novel genetic associations with complex diseases and their endophenotypes. Functional studies are needed to determine whether ECRG4 or HDAC9 is plausible as a therapeutic target.