Previously reported placebo-response-associated variants do not predict patient outcomes in inflammatory disease Phase III trial placebo arms.

In clinical trials, a placebo response refers to improvement in disease symptoms arising from the psychological effect of receiving a treatment rather than the actual treatment under investigation. Previous research has reported genomic variation associated with the likelihood of observing a placebo response, but these studies have been limited in scope and have not been validated. Here, we analyzed whole-genome sequencing data from 784 patients undergoing placebo treatment in Phase III Asthma or Rheumatoid Arthritis trials to assess the impact of previously reported variation on patient outcomes in the placebo arms and to identify novel variants associated with the placebo response. Contrary to expectations based on previous reports, we did not observe any statistically significant associations between genomic variants and placebo treatment outcome. Our findings suggest that the biological origin of the placebo response is complex and likely to be variable between disease areas.

geneAttribution: trait agnostic identification of candidate genes associated with noncoding variation.

Motivation: We have developed geneAttribution, an R package that assigns candidate causal gene(s) to a risk variant identified by a genetic association study such as a GWAS. The method combines user-supplied functional annotation such as expression quantitative trait loci (eQTL) or Hi-C genome conformation data and reports the most likely candidate genes. In the absence of annotation data, geneAttribution relies on the distances between the genes and the input variant. Availability and Implementation: The package is freely available from http://www.bioconductor.org/ . A quick-start vignette is included with the package. Contact: wustera@gene.com.

Evaluation of IFITM3 rs12252 Association With Severe Pediatric Influenza Infection.

Background: Interferon-induced transmembrane protein 3 (IFITM3) restricts endocytic fusion of influenza virus. IFITM3 rs12252_C, a putative alternate splice site, has been associated with influenza severity in adults. IFITM3 has not been evaluated in pediatric influenza. Methods: The Pediatric Influenza (PICFLU) study enrolled children with suspected influenza infection across 38 pediatric intensive care units during November 2008 to April 2016. IFITM3 was sequenced in patients and parents were genotyped for specific variants for family-based association testing. rs12252 was genotyped in 54 African-American pediatric outpatients with influenza (FLU09), included in the population-based comparisons with 1000 genomes. Splice site analysis of rs12252_C was performed using PICFLU and FLU09 patient RNA. Results: In PICFLU, 358 children had influenza infection. We identified 22 rs12252_C homozygotes in 185 white non-Hispanic children. rs12252_C was not associated with influenza infection in population or family-based analyses. We did not identify the Δ21 IFITM3 isoform in RNAseq data. The rs12252 genotype was not associated with IFITM3 expression levels, nor with critical illness severity. No novel rare IFITM3 functional variants were identified. Conclusions: rs12252 was not associated with susceptibility to influenza-related critical illness in children or with critical illness severity. Our data also do not support it being a splice site.

Identifying and mitigating batch effects in whole genome sequencing data.

BACKGROUND: Large sample sets of whole genome sequencing with deep coverage are being generated, however assembling datasets from different sources inevitably introduces batch effects. These batch effects are not well understood and can be due to changes in the sequencing protocol or bioinformatics tools used to process the data. No systematic algorithms or heuristics exist to detect and filter batch effects or remove associations impacted by batch effects in whole genome sequencing data. RESULTS: We describe key quality metrics, provide a freely available software package to compute them, and demonstrate that identification of batch effects is aided by principal components analysis of these metrics. To mitigate batch effects, we developed new site-specific filters that identified and removed variants that falsely associated with the phenotype due to batch effect. These include filtering based on: a haplotype based genotype correction, a differential genotype quality test, and removing sites with missing genotype rate greater than 30% after setting genotypes with quality scores less than 20 to missing. This method removed 96.1% of unconfirmed genome-wide significant SNP associations and 97.6% of unconfirmed genome-wide significant indel associations. We performed analyses to demonstrate that: 1) These filters impacted variants known to be disease associated as 2 out of 16 confirmed associations in an AMD candidate SNP analysis were filtered, representing a reduction in power of 12.5%, 2) In the absence of batch effects, these filters removed only a small proportion of variants across the genome (type I error rate of 3%), and 3) in an independent dataset, the method removed 90.2% of unconfirmed genome-wide SNP associations and 89.8% of unconfirmed genome-wide indel associations. CONCLUSIONS: Researchers currently do not have effective tools to identify and mitigate batch effects in whole genome sequencing data. We developed and validated methods and filters to address this deficiency.

Large-scale gene-centric meta-analysis across 32 studies identifies multiple lipid loci.

Genome-wide association studies (GWASs) have identified many SNPs underlying variations in plasma-lipid levels. We explore whether additional loci associated with plasma-lipid phenotypes, such as high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC), and triglycerides (TGs), can be identified by a dense gene-centric approach. Our meta-analysis of 32 studies in 66,240 individuals of European ancestry was based on the custom ∼50,000 SNP genotyping array (the ITMAT-Broad-CARe array) covering ∼2,000 candidate genes. SNP-lipid associations were replicated either in a cohort comprising an additional 24,736 samples or within the Global Lipid Genetic Consortium. We identified four, six, ten, and four unreported SNPs in established lipid genes for HDL-C, LDL-C, TC, and TGs, respectively. We also identified several lipid-related SNPs in previously unreported genes: DGAT2, HCAR2, GPIHBP1, PPARG, and FTO for HDL-C; SOCS3, APOH, SPTY2D1, BRCA2, and VLDLR for LDL-C; SOCS3, UGT1A1, BRCA2, UBE3B, FCGR2A, CHUK, and INSIG2 for TC; and SERPINF2, C4B, GCK, GATA4, INSR, and LPAL2 for TGs. The proportion of explained phenotypic variance in the subset of studies providing individual-level data was 9.9% for HDL-C, 9.5% for LDL-C, 10.3% for TC, and 8.0% for TGs. This large meta-analysis of lipid phenotypes with the use of a dense gene-centric approach identified multiple SNPs not previously described in established lipid genes and several previously unknown loci. The explained phenotypic variance from this approach was comparable to that from a meta-analysis of GWAS data, suggesting that a focused genotyping approach can further increase the understanding of heritability of plasma lipids.

Using gene expression to improve the power of genome-wide association analysis.

BACKGROUND/AIMS: Genome-wide association (GWA) studies have reported susceptible regions in the human genome for many common diseases and traits; however, these loci only explain a minority of trait heritability. To boost the power of a GWA study, substantial research endeavors have been focused on integrating other available genomic information in the analysis. Advances in high through-put technologies have generated a wealth of genomic data and made combining SNP and gene expression data become feasible. RESULTS: In this paper, we propose a novel procedure to incorporate gene expression information into GWA analysis. This procedure utilizes weights constructed by gene expression measurements to adjust p values from a GWA analysis. RESULTS from simulation analyses indicate that the proposed procedures may achieve substantial power gains, while controlling family-wise type I error rates at the nominal level. To demonstrate the implementation of our proposed approach, we apply the weight adjustment procedure to a GWA study on serum interferon-regulated chemokine levels in systemic lupus erythematosus patients. The study results can provide valuable insights for the functional interpretation of GWA signals. AVAILABILITY: The R source code for implementing the proposed weighting procedure is available at http://www.biostat.umn.edu/∼yho/research.html.

Automating resequencing-based detection of insertion-deletion polymorphisms.

Structural and insertion-deletion (indel) variants have received considerable recent attention, partly because of their phenotypic consequences. Among these variants, the most common are small indels ( approximately 1-30 bp). Identifying and genotyping indels using sequence traces obtained from diploid samples requires extensive manual review, which makes large-scale studies inconvenient. We report a new algorithm, implemented in available software (PolyPhred version 6.0), to help automate detection and genotyping of indels from sequence traces. The algorithm identifies heterozygous individuals, which permits the discovery of low-frequency indels. It finds 80% of all indel polymorphisms with almost no false positives and finds 97% with a false discovery rate of 10%. Additionally, genotyping accuracy exceeds 99%, and it correctly infers indel length in 96% of the cases. Using this approach, we identify indels in the HapMap ENCODE regions, providing the first report of these polymorphisms in this data set.

Association of NCF2, IKZF1, IRF8, IFIH1, and TYK2 with systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is a complex trait characterised by the production of a range of auto-antibodies and a diverse set of clinical phenotypes. Currently, ~8% of the genetic contribution to SLE in Europeans is known, following publication of several moderate-sized genome-wide (GW) association studies, which identified loci with a strong effect (OR>1.3). In order to identify additional genes contributing to SLE susceptibility, we conducted a replication study in a UK dataset (870 cases, 5,551 controls) of 23 variants that showed moderate-risk for lupus in previous studies. Association analysis in the UK dataset and subsequent meta-analysis with the published data identified five SLE susceptibility genes reaching genome-wide levels of significance (P(comb)<5×10(-8)): NCF2 (P(comb) = 2.87×10(-11)), IKZF1 (P(comb) = 2.33×10(-9)), IRF8 (P(comb) = 1.24×10(-8)), IFIH1 (P(comb) = 1.63×10(-8)), and TYK2 (P(comb) = 3.88×10(-8)). Each of the five new loci identified here can be mapped into interferon signalling pathways, which are known to play a key role in the pathogenesis of SLE. These results increase the number of established susceptibility genes for lupus to ~30 and validate the importance of using large datasets to confirm associations of loci which moderately increase the risk for disease.

Common variants near FRK/COL10A1 and VEGFA are associated with advanced age-related macular degeneration.

Despite significant progress in the identification of genetic loci for age-related macular degeneration (AMD), not all of the heritability has been explained. To identify variants which contribute to the remaining genetic susceptibility, we performed the largest meta-analysis of genome-wide association studies to date for advanced AMD. We imputed 6 036 699 single-nucleotide polymorphisms with the 1000 Genomes Project reference genotypes on 2594 cases and 4134 controls with follow-up replication of top signals in 5640 cases and 52 174 controls. We identified two new common susceptibility alleles, rs1999930 on 6q21-q22.3 near FRK/COL10A1 [odds ratio (OR) 0.87; P = 1.1 × 10(-8)] and rs4711751 on 6p12 near VEGFA (OR 1.15; P = 8.7 × 10(-9)). In addition to the two novel loci, 10 previously reported loci in ARMS2/HTRA1 (rs10490924), CFH (rs1061170, and rs1410996), CFB (rs641153), C3 (rs2230199), C2 (rs9332739), CFI (rs10033900), LIPC (rs10468017), TIMP3 (rs9621532) and CETP (rs3764261) were confirmed with genome-wide significant signals in this large study. Loci in the recently reported genes ABCA1 and COL8A1 were also detected with suggestive evidence of association with advanced AMD. The novel variants identified in this study suggest that angiogenesis (VEGFA) and extracellular collagen matrix (FRK/COL10A1) pathways contribute to the development of advanced AMD.

Heritability and genome-wide association study to assess genetic differences between advanced age-related macular degeneration subtypes.

PURPOSE: To investigate whether the 2 subtypes of advanced age-related macular degeneration (AMD), choroidal neovascularization (CNV), and geographic atrophy (GA) segregate separately in families and to identify which genetic variants are associated with these 2 subtypes. DESIGN: Sibling correlation study and genome-wide association study (GWAS). PARTICIPANTS: For the sibling correlation study, 209 sibling pairs with advanced AMD were included. For the GWAS, 2594 participants with advanced AMD subtypes and 4134 controls were included. Replication cohorts included 5383 advanced AMD participants and 15 240 controls. METHODS: Participants had the AMD grade assigned based on fundus photography, examination, or both. To determine heritability of advanced AMD subtypes, a sibling correlation study was performed. For the GWAS, genome-wide genotyping was conducted and 6 036 699 single nucleotide polymorphisms (SNPs) were imputed. Then, the SNPs were analyzed with a generalized linear model controlling for genotyping platform and genetic ancestry. The most significant associations were evaluated in independent cohorts. MAIN OUTCOME MEASURES: Concordance of advanced AMD subtypes in sibling pairs and associations between SNPs with GA and CNV advanced AMD subtypes. RESULTS: The difference between the observed and expected proportion of siblings concordant for the same subtype of advanced AMD was different to a statistically significant degree (P = 4.2 × 10(-5)), meaning that in siblings of probands with CNV or GA, the same advanced subtype is more likely to develop. In the analysis comparing participants with CNV to those with GA, a statistically significant association was observed at the ARMS2/HTRA1 locus (rs10490924; odds ratio [OR], 1.47; P = 4.3 × 10(-9)), which was confirmed in the replication samples (OR, 1.38; P = 7.4 × 10(-14) for combined discovery and replication analysis). CONCLUSIONS: Whether CNV versus GA develops in a patient with AMD is determined in part by genetic variation. In this large GWAS meta-analysis and replication analysis, the ARMS2/HTRA1 locus confers increased risk for both advanced AMD subtypes, but imparts greater risk for CNV than for GA. This locus explains a small proportion of the excess sibling correlation for advanced AMD subtype. Other loci were detected with suggestive associations that differ for advanced AMD subtypes and deserve follow-up in additional studies.

Analysis of protein-altering variants in telomerase genes and their association with MUC5B common variant status in patients with idiopathic pulmonary fibrosis: a candidate gene sequencing study.

BACKGROUND: Idiopathic pulmonary fibrosis (IPF) risk has a strong genetic component. Studies have implicated variations at several loci, including TERT, surfactant genes, and a single nucleotide polymorphism at chr11p15 (rs35705950) in the intergenic region between TOLLIP and MUC5B. Patients with IPF who have risk alleles at rs35705950 have longer survival from the time of IPF diagnosis than do patients homozygous for the non-risk allele, whereas patients with shorter telomeres have shorter survival times. We aimed to assess whether rare protein-altering variants in genes regulating telomere length are enriched in patients with IPF homozygous for the non-risk alleles at rs35705950. METHODS: Between Nov 1, 2014, and Nov 1, 2016, we assessed blood samples from patients aged 40 years or older and of European ancestry with sporadic IPF from three international phase 3 clinical trials (INSPIRE, CAPACITY, ASCEND), one phase 2 study (RIFF), and US-based observational studies (Vanderbilt Clinical Interstitial Lung Disease Registry and the UCSF Interstitial Lung Disease Clinic registry cohorts) at the Broad Institute (Cambridge, MA, USA) and Human Longevity (San Diego, CA, USA). We also assessed blood samples from non-IPF controls in several clinical trials. We did whole-genome sequencing to assess telomere length and identify rare protein-altering variants, stratified by rs35705950 genotype. We also assessed rare functional variation in TERT exons and compared telomere length and disease progression across genotypes. FINDINGS: We assessed samples from 1510 patients with IPF and 1874 non-IPF controls. 30 (3%) of 1046 patients with an rs35705950 risk allele had a rare protein-altering variant in TERT compared with 34 (7%) of 464 non-risk allele carriers (odds ratio 0·40 [95% CI 0·24-0·66], p=0·00039). Subsequent analyses identified enrichment of rare protein-altering variants in PARN and RTEL1, and rare variation in TERC in patients with IPF compared with controls. We expanded our study population to provide a more accurate estimation of rare variant frequency in these four loci, and to calculate telomere length. The proportion of patients with at least one rare variant in TERT, PARN, TERC, or RTEL1 was higher in patients with IPF than in controls (149 [9%] of 1739 patients vs 205 [2%] of 8645 controls, p=2·44 × 10-8). Patients with IPF who had a variant in any of the four identified telomerase component genes had telomeres that were 3·69-16·10% shorter than patients without a variant in any of the four genes and had an earlier mean age of disease onset than patients without one or more variants (65·1 years [SD 7·8] vs 67·1 years [7·9], p=0·004). In the placebo arms of clinical trials, shorter telomeres were significantly associated with faster disease progression (1·7% predicted forced vital capacity per kb per year, p=0·002). Pirfenidone had treatment benefit regardless of telomere length (p=4·24 × 10-8 for telomere length lower than the median, p=0·0044 for telomere length greater than the median). INTERPRETATION: Rare protein-altering variants in TERT, PARN, TERC, and RTEL1 are enriched in patients with IPF compared with controls, and, in the case of TERT, particularly in individuals without a risk allele at the rs35705950 locus. This suggests that multiple genetic factors contribute to sporadic IPF, which might implicate distinct mechanisms of pathogenesis and disease progression. FUNDING: Genentech, National Institutes of Health, Francis Family Foundation, Pulmonary Fibrosis Foundation, Nina Ireland Program for Lung Health, US Department of Veterans Affairs.

Targeting factor D of the alternative complement pathway reduces geographic atrophy progression secondary to age-related macular degeneration.

Geographic atrophy is an advanced form of age-related macular degeneration (AMD) and a leading cause of vision loss for which there are no approved treatments. Genetic studies in AMD patients have implicated dysregulation of the alternative complement pathway in the pathogenesis of geographic atrophy. Lampalizumab is a potential therapeutic that targets complement factor D, a pivotal activator of the alternative complement pathway. The MAHALO phase 2 clinical trial was a multicenter, randomized, controlled study that evaluated lampalizumab administered by intravitreal injection monthly (n = 42) and every other month (n = 41) versus sham control (n = 40) in patients with geographic atrophy secondary to AMD. The primary endpoint was the mean change in lesion area from baseline to month 18 as measured by fundus autofluorescence. Specific AMD-associated genetic polymorphisms were also analyzed. The MAHALO study met its primary efficacy endpoint with an acceptable safety profile; monthly lampalizumab treatment demonstrated a 20% reduction in lesion area progression versus sham control [80% confidence interval (CI), 4 to 37%]. A more substantial monthly treatment benefit of 44% reduction in geographic atrophy area progression versus sham control (95% CI, 15 to 73%) was observed in a subgroup of complement factor I (CFI) risk-allele carriers (57% of the patients analyzed were CFI risk-allele carriers). The MAHALO study shows a potential treatment effect in patients with geographic atrophy and supports therapeutic targeting of the alternative complement pathway for treating AMD pathogenesis.

A meta-analysis of genome-wide association studies identifies 17 new Parkinson's disease risk loci.

Common variant genome-wide association studies (GWASs) have, to date, identified >24 risk loci for Parkinson's disease (PD). To discover additional loci, we carried out a GWAS comparing 6,476 PD cases with 302,042 controls, followed by a meta-analysis with a recent study of over 13,000 PD cases and 95,000 controls at 9,830 overlapping variants. We then tested 35 loci (P < 1 × 10-6) in a replication cohort of 5,851 cases and 5,866 controls. We identified 17 novel risk loci (P < 5 × 10-8) in a joint analysis of 26,035 cases and 403,190 controls. We used a neurocentric strategy to assign candidate risk genes to the loci. We identified protein-altering or cis-expression quantitative trait locus (cis-eQTL) variants in linkage disequilibrium with the index variant in 29 of the 41 PD loci. These results indicate a key role for autophagy and lysosomal biology in PD risk, and suggest potential new drug targets for PD.

A Common Variant of IL-6R is Associated with Elevated IL-6 Pathway Activity in Alzheimer's Disease Brains.

The common p.D358A variant (rs2228145) in IL-6R is associated with risk for multiple diseases and with increased levels of soluble IL-6R in the periphery and central nervous system (CNS). Here, we show that the p.D358A allele leads to increased proteolysis of membrane bound IL-6R and demonstrate that IL-6R peptides with A358 are more susceptible to cleavage by ADAM10 and ADAM17. IL-6 responsive genes were identified in primary astrocytes and microglia and an IL-6 gene signature was increased in the CNS of late onset Alzheimer's disease subjects in an IL6R allele dependent manner. We conducted a screen to identify variants associated with the age of onset of Alzheimer's disease in APOE ɛ4 carriers. Across five datasets, p.D358A had a meta P = 3 ×10-4 and an odds ratio = 1.3, 95% confidence interval 1.12 -1.48. Our study suggests that a common coding region variant of the IL-6 receptor results in neuroinflammatory changes that may influence the age of onset of Alzheimer's disease in APOE ɛ4 carriers.

TYK2 protein-coding variants protect against rheumatoid arthritis and autoimmunity, with no evidence of major pleiotropic effects on non-autoimmune complex traits.

Despite the success of genome-wide association studies (GWAS) in detecting a large number of loci for complex phenotypes such as rheumatoid arthritis (RA) susceptibility, the lack of information on the causal genes leaves important challenges to interpret GWAS results in the context of the disease biology. Here, we genetically fine-map the RA risk locus at 19p13 to define causal variants, and explore the pleiotropic effects of these same variants in other complex traits. First, we combined Immunochip dense genotyping (n = 23,092 case/control samples), Exomechip genotyping (n = 18,409 case/control samples) and targeted exon-sequencing (n = 2,236 case/controls samples) to demonstrate that three protein-coding variants in TYK2 (tyrosine kinase 2) independently protect against RA: P1104A (rs34536443, OR = 0.66, P = 2.3 x 10(-21)), A928V (rs35018800, OR = 0.53, P = 1.2 x 10(-9)), and I684S (rs12720356, OR = 0.86, P = 4.6 x 10(-7)). Second, we show that the same three TYK2 variants protect against systemic lupus erythematosus (SLE, Pomnibus = 6 x 10(-18)), and provide suggestive evidence that two of the TYK2 variants (P1104A and A928V) may also protect against inflammatory bowel disease (IBD; P(omnibus) = 0.005). Finally, in a phenome-wide association study (PheWAS) assessing >500 phenotypes using electronic medical records (EMR) in >29,000 subjects, we found no convincing evidence for association of P1104A and A928V with complex phenotypes other than autoimmune diseases such as RA, SLE and IBD. Together, our results demonstrate the role of TYK2 in the pathogenesis of RA, SLE and IBD, and provide supporting evidence for TYK2 as a promising drug target for the treatment of autoimmune diseases.

A rare mutation in UNC5C predisposes to late-onset Alzheimer's disease and increases neuronal cell death.

We have identified a rare coding mutation, T835M (rs137875858), in the UNC5C netrin receptor gene that segregated with disease in an autosomal dominant pattern in two families enriched for late-onset Alzheimer's disease and that was associated with disease across four large case-control cohorts (odds ratio = 2.15, Pmeta = 0.0095). T835M alters a conserved residue in the hinge region of UNC5C, and in vitro studies demonstrate that this mutation leads to increased cell death in human HEK293T cells and in rodent neurons. Furthermore, neurons expressing T835M UNC5C are more susceptible to cell death from multiple neurotoxic stimuli, including ß-amyloid (Aß), glutamate and staurosporine. On the basis of these data and the enriched hippocampal expression of UNC5C in the adult nervous system, we propose that one possible mechanism in which T835M UNC5C contributes to the risk of Alzheimer's disease is by increasing susceptibility to neuronal cell death, particularly in vulnerable regions of the Alzheimer's disease brain.

Estimating coverage and power for genetic association studies using near-complete variation data.

Although studies suggest that SNPs derived from HapMap provide promising coverage and power for association studies, the lack of alternative variation datasets limits independent analysis. Using near-complete variation data for 76 genes resequenced in HapMap samples, we find that coverage of common variation by commercial genotyping arrays is substantially lower compared to the HapMap-based estimates. We quantify the power offered by these arrays for a range of disease models.

Comprehensive identification and characterization of diallelic insertion-deletion polymorphisms in 330 human candidate genes.

Despite being the second most frequent type of polymorphism in the genome, diallelic insertion-deletion polymorphisms (indels) have received far less attention in the study of sequence variation. In this report, we describe an approach that can detect indels in the heterozygous state and can comprehensively identify indels in the target sequence. Using this approach, we identified 2393 indels in a set of 330 candidate genes, i.e. an average of seven indels per gene with about two indels per gene being common (minor allele frequency >or=0.1). We compared the population genetic characteristics of indels with substitutions in this data. Our data supported the findings that deletions occur more frequently in the human genome. 5'-UTR and coding regions of the genes showed a significantly lower diversity for indels compared with other regions, suggesting differences in effects of selection on indels and substitutions. Sequence diversity and pairwise linkage disequilibrium (LD) findings of the different populations were similar to earlier results and included a greater skew towards low-frequency variants and a faster rate of LD decay in the African-descent population compared with the non-African populations. Within populations, the allele frequency spectra and LD-decay profiles for indels were similar to substitutions. Overall, the findings suggest that, although the mechanisms giving rise to indels may be different from those causing substitutions, the evolutionary histories of indels and substitutions are similar, and that indels can play a valuable role in association studies and marker selection strategies.