Publications by authors named "Lindsay A Farrer"

254 Publications

Association of mitochondrial variants and haplogroups identified by whole exome sequencing with Alzheimer's disease.

Alzheimers Dement 2021 Jun 20. Epub 2021 Jun 20.

Department of Medicine (Biomedical Genetics), Boston University School of Medicine, 72 East Concord Street, Boston, Massachusetts, 02118, USA.

Introduction: Findings regarding the association between mitochondrial DNA (mtDNA) variants and Alzheimer's disease (AD) are inconsistent.

Methods: We developed a pipeline for accurate assembly and variant calling in mitochondrial genomes embedded within whole exome sequences (WES) from 10,831 participants from the Alzheimer's Disease Sequencing Project (ADSP). Association of AD risk was evaluated with each mtDNA variant and variants located in 1158 nuclear genes related to mitochondrial function using the SCORE test. Gene-based tests were performed using SKAT-O.

Results: Analysis of 4220 mtDNA variants revealed study-wide significant association of AD with a rare MT-ND4L missense variant (rs28709356; minor allele frequency = 0.002; P = 7.3 × 10 ) as well as with MT-ND4L in a gene-based test (P = 6.71 × 10 ). Significant association was also observed with a MT-related nuclear gene, TAMM41, in a gene-based test (P = 2.7 × 10 ). The expression of TAMM41 was lower in AD cases than controls (P = .00046) or mild cognitive impairment cases (P = .03).

Discussion: Significant findings in MT-ND4L and TAMM41 provide evidence for a role of mitochondria in AD.
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http://dx.doi.org/10.1002/alz.12396DOI Listing
June 2021

Genome-wide association study of phenotypes measuring progression from first cocaine or opioid use to dependence reveals novel risk genes.

Explor Med 2021 28;2:60-73. Epub 2021 Feb 28.

Department of Medicine (Biomedical Genetics), Boston University School of Medicine, Boston, MA 02118, USA.

Aim: Substance use disorders (SUD) result in substantial morbidity and mortality worldwide. Opioids, and to a lesser extent cocaine, contribute to a large percentage of this health burden. Despite their high heritability, few genetic risk loci have been identified for either opioid or cocaine dependence (OD or CD, respectively). A genome-wide association study of OD and CD related phenotypes reflecting the time between first self-reported use of these substances and a first DSM-IV dependence diagnosis was conducted.

Methods: Cox proportional hazards regression in a discovery sample of 6,188 African-Americans (AAs) and 6,835 European-Americans (EAs) participants in a genetic study of multiple substance dependence phenotypes were used to test for association between genetic variants and these outcomes. The top findings were tested for replication in two independent cohorts.

Results: In the discovery sample, three independent regions containing variants associated with time to dependence at < 5 x 10 were identified, one (rs61835088 = 1.03 x 10) for cocaine in the combined EA-AA meta-analysis in the gene on chromosome 1, and two for opioids in the AA portion of the sample in intergenic regions of chromosomes 4 (rs4860439, = 1.37 x 10) and 9 (rs7032521, = 3.30 x 10). After meta-analysis with data from the replication cohorts, the signal at rs61835088 improved (HR = 0.87, = 3.71 x 10 and an intergenic SNP on chromosome 21 (rs2825295, HR = 1.14, = 2.57 x 10) that missed the significance threshold in the AA discovery sample became genome-wide significant (GWS) for CD.

Conclusions: Although the two GWS variants are not in genes with obvious links to SUD biology and have modest effect sizes, they are statistically robust and show evidence for association in independent samples. These results may point to novel pathways contributing to disease progression and highlight the utility of related phenotypes to better understand the genetics of SUDs.
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http://dx.doi.org/10.37349/emed.2021.00032DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8192073PMC
February 2021

Common variants in Alzheimer's disease and risk stratification by polygenic risk scores.

Nat Commun 2021 06 7;12(1):3417. Epub 2021 Jun 7.

Servei de Neurologia, Hospital Universitari i Politècnic La Fe, Valencia, Spain.

Genetic discoveries of Alzheimer's disease are the drivers of our understanding, and together with polygenetic risk stratification can contribute towards planning of feasible and efficient preventive and curative clinical trials. We first perform a large genetic association study by merging all available case-control datasets and by-proxy study results (discovery n = 409,435 and validation size n = 58,190). Here, we add six variants associated with Alzheimer's disease risk (near APP, CHRNE, PRKD3/NDUFAF7, PLCG2 and two exonic variants in the SHARPIN gene). Assessment of the polygenic risk score and stratifying by APOE reveal a 4 to 5.5 years difference in median age at onset of Alzheimer's disease patients in APOE ɛ4 carriers. Because of this study, the underlying mechanisms of APP can be studied to refine the amyloid cascade and the polygenic risk score provides a tool to select individuals at high risk of Alzheimer's disease.
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http://dx.doi.org/10.1038/s41467-021-22491-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8184987PMC
June 2021

Cell-type-specific expression quantitative trait loci associated with Alzheimer disease in blood and brain tissue.

Transl Psychiatry 2021 Apr 27;11(1):250. Epub 2021 Apr 27.

Bioinformatics Graduate Program, Boston University, Boston, MA, USA.

Because regulation of gene expression is heritable and context-dependent, we investigated AD-related gene expression patterns in cell types in blood and brain. Cis-expression quantitative trait locus (eQTL) mapping was performed genome-wide in blood from 5257 Framingham Heart Study (FHS) participants and in brain donated by 475 Religious Orders Study/Memory & Aging Project (ROSMAP) participants. The association of gene expression with genotypes for all cis SNPs within 1 Mb of genes was evaluated using linear regression models for unrelated subjects and linear-mixed models for related subjects. Cell-type-specific eQTL (ct-eQTL) models included an interaction term for the expression of "proxy" genes that discriminate particular cell type. Ct-eQTL analysis identified 11,649 and 2533 additional significant gene-SNP eQTL pairs in brain and blood, respectively, that were not detected in generic eQTL analysis. Of note, 386 unique target eGenes of significant eQTLs shared between blood and brain were enriched in apoptosis and Wnt signaling pathways. Five of these shared genes are established AD loci. The potential importance and relevance to AD of significant results in myeloid cell types is supported by the observation that a large portion of GWS ct-eQTLs map within 1 Mb of established AD loci and 58% (23/40) of the most significant eGenes in these eQTLs have previously been implicated in AD. This study identified cell-type-specific expression patterns for established and potentially novel AD genes, found additional evidence for the role of myeloid cells in AD risk, and discovered potential novel blood and brain AD biomarkers that highlight the importance of cell-type-specific analysis.
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http://dx.doi.org/10.1038/s41398-021-01373-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8079392PMC
April 2021

Set-Based Rare Variant Expression Quantitative Trait Loci in Blood and Brain from Alzheimer Disease Study Participants.

Genes (Basel) 2021 Mar 15;12(3). Epub 2021 Mar 15.

Bioinformatics Graduate Program, Boston University, Boston, MA 02215, USA.

Because studies of rare variant effects on gene expression have limited power, we investigated set-based methods to identify rare expression quantitative trait loci (eQTL) related to Alzheimer disease (AD). Gene-level and pathway-level cis rare-eQTL mapping was performed genome-wide using gene expression data derived from blood donated by 713 Alzheimer's Disease Neuroimaging Initiative participants and from brain tissues donated by 475 Religious Orders Study/Memory and Aging Project participants. The association of gene or pathway expression with a set of all cis potentially regulatory low-frequency and rare variants within 1 Mb of genes was evaluated using SKAT-O. A total of 65 genes expressed in the brain were significant targets for rare expression single nucleotide polymorphisms (eSNPs) among which 17% (11/65) included established AD genes and . In the blood, 307 genes were significant targets for rare eSNPs. In the blood and the brain, , , , , and were targets for significant eSNPs. Pathway enrichment analysis revealed significant pathways in the brain ( = 9) and blood ( = 16). Pathways for apoptosis signaling, cholecystokinin receptor (CCKR) signaling, and inflammation mediated by chemokine and cytokine signaling were common to both tissues. Significant rare eQTLs in inflammation pathways included five genes in the blood (, , , , ) that were previously linked to AD. This study identified several significant gene- and pathway-level rare eQTLs, which further confirmed the importance of the immune system and inflammation in AD and highlighted the advantages of using a set-based eQTL approach for evaluating the effect of low-frequency and rare variants on gene expression.
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http://dx.doi.org/10.3390/genes12030419DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7999141PMC
March 2021

Identifying factors associated with opioid cessation in a biracial sample using machine learning.

Explor Med 2020 29;1(1):27-41. Epub 2020 Feb 29.

Department of Medicine (Biomedical Genetics), Boston University School of Medicine, Boston, MA 02118, USA.

Aim: Racial disparities in opioid use disorder (OUD) management exist, however, and there is limited research on factors that influence opioid cessation in different population groups.

Methods: We employed multiple machine learning prediction algorithms least absolute shrinkage and selection operator, random forest, deep neural network, and support vector machine to assess factors associated with ceasing opioid use in a sample of 1,192 African Americans (AAs) and 2,557 individuals of European ancestry (EAs) who met Diagnostic and Statistical Manual of Mental Disorders, 5th Edition criteria for OUD. Values for nearly 4,000 variables reflecting demographics, alcohol and other drug use, general health, non-drug use behaviors, and diagnoses for other psychiatric disorders, were obtained for each participant from the Semi-Structured Assessment for Drug Dependence and Alcoholism, a detailed semi-structured interview.

Results: Support vector machine models performed marginally better on average than other machine learning methods with maximum prediction accuracies of 75.4% in AAs and 79.4% in EAs. Subsequent stepwise regression considered the 83 most highly ranked variables across all methods and models and identified less recent cocaine use (AAs: odds ratio (OR) = 1.82, = 9.19 × 10; EAs: OR = 1.91, = 3.30 × 10), shorter duration of opioid use (AAs: OR = 0.55, = 5.78 × 10; EAs: OR = 0.69, = 3.01 × 10), and older age (AAs: OR = 2.44, = 1.41 × 10; EAs: OR = 2.00, = 5.74 × 10) as the strongest independent predictors of opioid cessation in both AAs and EAs. Attending self-help groups for OUD was also an independent predictor ( < 0.05) in both population groups, while less gambling severity (OR = 0.80, = 3.32 × 10) was specific to AAs and post-traumatic stress disorder recovery (OR = 1.93, = 7.88 × 10), recent antisocial behaviors (OR = 0.64, = 2.69 × 10), and atheism (OR = 1.45, = 1.34 × 10) were specific to EAs. Factors related to drug use comprised about half of the significant independent predictors in both AAs and EAs, with other predictors related to non-drug use behaviors, psychiatric disorders, overall health, and demographics.

Conclusions: These proof-of-concept findings provide avenues for hypothesis-driven analysis, and will lead to further research on strategies to improve OUD management in EAs and AAs.
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http://dx.doi.org/10.37349/emed.2020.00003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7861053PMC
February 2020

Analysis of telomere length variation and Shelterin complex subunit gene expression changes in ethanol-exposed human embryonic stem cells.

J Psychiatr Res 2020 Nov 17. Epub 2020 Nov 17.

Department of Psychiatry, Boston University School of Medicine, Boston, MA, USA; Department of Medicine (Biomedical Genetics), Boston University School of Medicine, Boston, MA, USA. Electronic address:

Telomeres protect chromosome ends from degradation. Telomere length (TL) can be altered by aging and environmental stress. Shortened TL has been observed in peripheral blood leukocytes of alcohol dependent subjects and ethanol-exposed somatic cells. To understand the impact of ethanol on telomeres in pluripotent stem cells, we investigated the influence of ethanol on TL and the expression of six Shelterin complex subunit or telomere-regulating genes (POT1, RAP1, TIN2, TPP1, TRF1, and TRF2) in human embryonic stem cells (hESCs), which were exposed to 0, 25, 50, or 100 mM of ethanol for 3, 7, or 14 days. Ethanol-induced TL and Shelterin complex subunit gene expression changes were examined by quantitative polymerase chain reactions. Two-way ANOVA tests indicated that TL variation and expression changes of four associated Shelterin complex subunit genes (POT1, TPP1, TIN2, and TRF2) were mainly dependent on the length of ethanol exposure, while TRF1 and RAP1expression was influenced by ethanol concentration, exposure time, and the interaction of ethanol concentration and exposure time. Tukey's multiple comparison tests showed that TL and the expression of POT1, RAP1, TIN2, TPP1, and TRF1 were decreased after a 7-day (versus a 3-day) ethanol exposure. However, the decreased expression of all six Shelterin complex subunit genes was recovered and TL was not further shortened after a 14-day (versus a 7-day) ethanol exposure, likely due to the adaptation of hESCs to ethanol-induced stress. Our study provided further evidence that TL is regulated and maintained by telomere-regulating genes in stem cells under ethanol stress.
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http://dx.doi.org/10.1016/j.jpsychires.2020.11.027DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8126580PMC
November 2020

Expanding the genetic architecture of nicotine dependence and its shared genetics with multiple traits.

Nat Commun 2020 11 3;11(1):5562. Epub 2020 Nov 3.

Department of Genetic Epidemiology in Psychiatry, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, 68159, Mannheim, Germany.

Cigarette smoking is the leading cause of preventable morbidity and mortality. Genetic variation contributes to initiation, regular smoking, nicotine dependence, and cessation. We present a Fagerström Test for Nicotine Dependence (FTND)-based genome-wide association study in 58,000 European or African ancestry smokers. We observe five genome-wide significant loci, including previously unreported loci MAGI2/GNAI1 (rs2714700) and TENM2 (rs1862416), and extend loci reported for other smoking traits to nicotine dependence. Using the heaviness of smoking index from UK Biobank (N = 33,791), rs2714700 is consistently associated; rs1862416 is not associated, likely reflecting nicotine dependence features not captured by the heaviness of smoking index. Both variants influence nearby gene expression (rs2714700/MAGI2-AS3 in hippocampus; rs1862416/TENM2 in lung), and expression of genes spanning nicotine dependence-associated variants is enriched in cerebellum. Nicotine dependence (SNP-based heritability = 8.6%) is genetically correlated with 18 other smoking traits (r = 0.40-1.09) and co-morbidities. Our results highlight nicotine dependence-specific loci, emphasizing the FTND as a composite phenotype that expands genetic knowledge of smoking.
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http://dx.doi.org/10.1038/s41467-020-19265-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7642344PMC
November 2020

A large-scale genome-wide association study meta-analysis of cannabis use disorder.

Lancet Psychiatry 2020 12 20;7(12):1032-1045. Epub 2020 Oct 20.

Stanford University Graduate School of Education, Stanford University, Stanford, CA, USA.

Background: Variation in liability to cannabis use disorder has a strong genetic component (estimated twin and family heritability about 50-70%) and is associated with negative outcomes, including increased risk of psychopathology. The aim of the study was to conduct a large genome-wide association study (GWAS) to identify novel genetic variants associated with cannabis use disorder.

Methods: To conduct this GWAS meta-analysis of cannabis use disorder and identify associations with genetic loci, we used samples from the Psychiatric Genomics Consortium Substance Use Disorders working group, iPSYCH, and deCODE (20 916 case samples, 363 116 control samples in total), contrasting cannabis use disorder cases with controls. To examine the genetic overlap between cannabis use disorder and 22 traits of interest (chosen because of previously published phenotypic correlations [eg, psychiatric disorders] or hypothesised associations [eg, chronotype] with cannabis use disorder), we used linkage disequilibrium score regression to calculate genetic correlations.

Findings: We identified two genome-wide significant loci: a novel chromosome 7 locus (FOXP2, lead single-nucleotide polymorphism [SNP] rs7783012; odds ratio [OR] 1·11, 95% CI 1·07-1·15, p=1·84 × 10) and the previously identified chromosome 8 locus (near CHRNA2 and EPHX2, lead SNP rs4732724; OR 0·89, 95% CI 0·86-0·93, p=6·46 × 10). Cannabis use disorder and cannabis use were genetically correlated (r 0·50, p=1·50 × 10), but they showed significantly different genetic correlations with 12 of the 22 traits we tested, suggesting at least partially different genetic underpinnings of cannabis use and cannabis use disorder. Cannabis use disorder was positively genetically correlated with other psychopathology, including ADHD, major depression, and schizophrenia.

Interpretation: These findings support the theory that cannabis use disorder has shared genetic liability with other psychopathology, and there is a distinction between genetic liability to cannabis use and cannabis use disorder.

Funding: National Institute of Mental Health; National Institute on Alcohol Abuse and Alcoholism; National Institute on Drug Abuse; Center for Genomics and Personalized Medicine and the Centre for Integrative Sequencing; The European Commission, Horizon 2020; National Institute of Child Health and Human Development; Health Research Council of New Zealand; National Institute on Aging; Wellcome Trust Case Control Consortium; UK Research and Innovation Medical Research Council (UKRI MRC); The Brain & Behavior Research Foundation; National Institute on Deafness and Other Communication Disorders; Substance Abuse and Mental Health Services Administration (SAMHSA); National Institute of Biomedical Imaging and Bioengineering; National Health and Medical Research Council (NHMRC) Australia; Tobacco-Related Disease Research Program of the University of California; Families for Borderline Personality Disorder Research (Beth and Rob Elliott) 2018 NARSAD Young Investigator Grant; The National Child Health Research Foundation (Cure Kids); The Canterbury Medical Research Foundation; The New Zealand Lottery Grants Board; The University of Otago; The Carney Centre for Pharmacogenomics; The James Hume Bequest Fund; National Institutes of Health: Genes, Environment and Health Initiative; National Institutes of Health; National Cancer Institute; The William T Grant Foundation; Australian Research Council; The Virginia Tobacco Settlement Foundation; The VISN 1 and VISN 4 Mental Illness Research, Education, and Clinical Centers of the US Department of Veterans Affairs; The 5th Framework Programme (FP-5) GenomEUtwin Project; The Lundbeck Foundation; NIH-funded Shared Instrumentation Grant S10RR025141; Clinical Translational Sciences Award grants; National Institute of Neurological Disorders and Stroke; National Heart, Lung, and Blood Institute; National Institute of General Medical Sciences.
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http://dx.doi.org/10.1016/S2215-0366(20)30339-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7674631PMC
December 2020

Novel Alzheimer Disease Risk Loci and Pathways in African American Individuals Using the African Genome Resources Panel: A Meta-analysis.

JAMA Neurol 2021 01;78(1):102-113

Taub Institute for Research on Alzheimer's Disease and the Aging Brain, Columbia University, New York, New York.

Importance: Compared with non-Hispanic White individuals, African American individuals from the same community are approximately twice as likely to develop Alzheimer disease. Despite this disparity, the largest Alzheimer disease genome-wide association studies to date have been conducted in non-Hispanic White individuals. In the largest association analyses of Alzheimer disease in African American individuals, ABCA7, TREM2, and an intergenic locus at 5q35 were previously implicated.

Objective: To identify additional risk loci in African American individuals by increasing the sample size and using the African Genome Resource panel.

Design, Setting, And Participants: This genome-wide association meta-analysis used case-control and family-based data sets from the Alzheimer Disease Genetics Consortium. There were multiple recruitment sites throughout the United States that included individuals with Alzheimer disease and controls of African American ancestry. Analysis began October 2018 and ended September 2019.

Main Outcomes And Measures: Diagnosis of Alzheimer disease.

Results: A total of 2784 individuals with Alzheimer disease (1944 female [69.8%]) and 5222 controls (3743 female [71.7%]) were analyzed (mean [SD] age at last evaluation, 74.2 [13.6] years). Associations with 4 novel common loci centered near the intracellular glycoprotein trafficking gene EDEM1 (3p26; P = 8.9 × 10-7), near the immune response gene ALCAM (3q13; P = 9.3 × 10-7), within GPC6 (13q31; P = 4.1 × 10-7), a gene critical for recruitment of glutamatergic receptors to the neuronal membrane, and within VRK3 (19q13.33; P = 3.5 × 10-7), a gene involved in glutamate neurotoxicity, were identified. In addition, several loci associated with rare variants, including a genome-wide significant intergenic locus near IGF1R at 15q26 (P = 1.7 × 10-9) and 6 additional loci with suggestive significance (P ≤ 5 × 10-7) such as API5 at 11p12 (P = 8.8 × 10-8) and RBFOX1 at 16p13 (P = 5.4 × 10-7) were identified. Gene expression data from brain tissue demonstrate association of ALCAM, ARAP1, GPC6, and RBFOX1 with brain β-amyloid load. Of 25 known loci associated with Alzheimer disease in non-Hispanic White individuals, only APOE, ABCA7, TREM2, BIN1, CD2AP, FERMT2, and WWOX were implicated at a nominal significance level or stronger in African American individuals. Pathway analyses strongly support the notion that immunity, lipid processing, and intracellular trafficking pathways underlying Alzheimer disease in African American individuals overlap with those observed in non-Hispanic White individuals. A new pathway emerging from these analyses is the kidney system, suggesting a novel mechanism for Alzheimer disease that needs further exploration.

Conclusions And Relevance: While the major pathways involved in Alzheimer disease etiology in African American individuals are similar to those in non-Hispanic White individuals, the disease-associated loci within these pathways differ.
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http://dx.doi.org/10.1001/jamaneurol.2020.3536DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7573798PMC
January 2021

Analysis of brain region-specific co-expression networks reveals clustering of established and novel genes associated with Alzheimer disease.

Alzheimers Res Ther 2020 09 2;12(1):103. Epub 2020 Sep 2.

Bioinformatics Graduate Program, Boston University, Boston, MA, USA.

Background: Identifying and understanding the functional role of genetic risk factors for Alzheimer disease (AD) has been complicated by the variability of genetic influences across brain regions and confounding with age-related neurodegeneration.

Methods: A gene co-expression network was constructed using data obtained from the Allen Brain Atlas for multiple brain regions (cerebral cortex, cerebellum, and brain stem) in six individuals. Gene network analyses were seeded with 52 reproducible (i.e., established) AD (RAD) genes. Genome-wide association study summary data were integrated with the gene co-expression results and phenotypic information (i.e., memory and aging-related outcomes) from gene knockout studies in Drosophila to generate rankings for other genes that may have a role in AD.

Results: We found that co-expression of the RAD genes is strongest in the cortical regions where neurodegeneration due to AD is most severe. There was significant evidence for two novel AD-related genes including EPS8 (FDR p = 8.77 × 10) and HSPA2 (FDR p = 0.245).

Conclusions: Our findings indicate that AD-related risk factors are potentially associated with brain region-specific effects on gene expression that can be detected using a gene network approach.
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http://dx.doi.org/10.1186/s13195-020-00674-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7469336PMC
September 2020

Genetic variants and functional pathways associated with resilience to Alzheimer's disease.

Brain 2020 08;143(8):2561-2575

Department of Neurology, Columbia University, New York, NY, USA.

Approximately 30% of older adults exhibit the neuropathological features of Alzheimer's disease without signs of cognitive impairment. Yet, little is known about the genetic factors that allow these potentially resilient individuals to remain cognitively unimpaired in the face of substantial neuropathology. We performed a large, genome-wide association study (GWAS) of two previously validated metrics of cognitive resilience quantified using a latent variable modelling approach and representing better-than-predicted cognitive performance for a given level of neuropathology. Data were harmonized across 5108 participants from a clinical trial of Alzheimer's disease and three longitudinal cohort studies of cognitive ageing. All analyses were run across all participants and repeated restricting the sample to individuals with unimpaired cognition to identify variants at the earliest stages of disease. As expected, all resilience metrics were genetically correlated with cognitive performance and education attainment traits (P-values < 2.5 × 10-20), and we observed novel correlations with neuropsychiatric conditions (P-values < 7.9 × 10-4). Notably, neither resilience metric was genetically correlated with clinical Alzheimer's disease (P-values > 0.42) nor associated with APOE (P-values > 0.13). In single variant analyses, we observed a genome-wide significant locus among participants with unimpaired cognition on chromosome 18 upstream of ATP8B1 (index single nucleotide polymorphism rs2571244, minor allele frequency = 0.08, P = 2.3 × 10-8). The top variant at this locus (rs2571244) was significantly associated with methylation in prefrontal cortex tissue at multiple CpG sites, including one just upstream of ATPB81 (cg19596477; P = 2 × 10-13). Overall, this comprehensive genetic analysis of resilience implicates a putative role of vascular risk, metabolism, and mental health in protection from the cognitive consequences of neuropathology, while also providing evidence for a novel resilience gene along the bile acid metabolism pathway. Furthermore, the genetic architecture of resilience appears to be distinct from that of clinical Alzheimer's disease, suggesting that a shift in focus to molecular contributors to resilience may identify novel pathways for therapeutic targets.
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http://dx.doi.org/10.1093/brain/awaa209DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7447518PMC
August 2020

Sex-dependent autosomal effects on clinical progression of Alzheimer's disease.

Brain 2020 07;143(7):2272-2280

Department of Radiology, University of California, San Diego, USA.

Sex differences in the manifestations of Alzheimer's disease are under intense investigation. Despite the emerging importance of polygenic predictions for Alzheimer's disease, sex-dependent polygenic effects have not been demonstrated. Here, using a sex crossover analysis, we show that sex-dependent autosomal genetic effects on Alzheimer's disease can be revealed by characterizing disease progress via the hazard function. We first performed sex-stratified genome-wide associations, and then applied derived sex-dependent weights to two independent cohorts. Relative to sex-mismatched scores, sex-matched polygenic hazard scores showed significantly stronger associations with age-at-disease-onset, clinical progression, amyloid deposition, neurofibrillary tangles, and composite neuropathological scores, independent of apolipoprotein E. Models without using hazard weights, i.e. polygenic risk scores, showed lower predictive power than polygenic hazard scores with no evidence for sex differences. Our results indicate that revealing sex-dependent genetic architecture requires the consideration of temporal processes of Alzheimer's disease. This has strong implications not only for the genetic underpinning of Alzheimer's disease but also for how we estimate sex-dependent polygenic effects for clinical use.
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http://dx.doi.org/10.1093/brain/awaa164DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7364740PMC
July 2020

Genome-wide association study of rate of cognitive decline in Alzheimer's disease patients identifies novel genes and pathways.

Alzheimers Dement 2020 08 23;16(8):1134-1145. Epub 2020 Jun 23.

Division of Genetics, Department of Medicine, Brigham and Women's Hospital, Boston, Massachusetts, USA.

Introduction: Variability exists in the disease trajectories of Alzheimer's disease (AD) patients. We performed a genome-wide association study to examine rate of cognitive decline (ROD) in patients with AD.

Methods: We tested for interactions between genetic variants and time since diagnosis to predict the ROD of a composite cognitive score in 3946 AD cases and performed pathway analysis on the top genes.

Results: Suggestive associations (P < 1.0 × 10 ) were observed on chromosome 15 in DNA polymerase-γ (rs3176205, P = 1.11 × 10 ), chromosome 7 (rs60465337,P = 4.06 × 10 ) in contactin-associated protein-2, in RP11-384F7.1 on chromosome 3 (rs28853947, P = 5.93 × 10 ), family with sequence similarity 214 member-A on chromosome 15 (rs2899492, P = 5.94 × 10 ), and intergenic regions on chromosomes 16 (rs4949142, P = 4.02 × 10 ) and 4 (rs1304013, P = 7.73 × 10 ). Significant pathways involving neuronal development and function, apoptosis, memory, and inflammation were identified.

Discussion: Pathways related to AD, intelligence, and neurological function determine AD progression, while previously identified AD risk variants, including the apolipoprotein (APOE) ε4 and ε2 variants, do not have a major impact.
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http://dx.doi.org/10.1002/alz.12106DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7924136PMC
August 2020

Prefrontal cortex eQTLs/mQTLs enriched in genetic variants associated with alcohol use disorder and other diseases.

Epigenomics 2020 05 4;12(9):789-800. Epub 2020 Jun 4.

Department of Psychiatry, Boston University School of Medicine, MA, USA.

This study aimed to investigate the function of genome-wide association study (GWAS)-identified variants associated with alcohol use disorder (AUD)/comorbid psychiatric disorders. Genome-wide genotype, transcriptome and DNA methylome data were obtained from postmortem prefrontal cortex (PFC) of 48 Caucasians (24 AUD cases/24 controls). Expression/methylation quantitative trait loci (eQTL/mQTL) were identified and their enrichment in GWAS signals for the above disorders were analyzed. PFC -eQTLs (923 from cases+controls, 27 from cases and 98 from controls) and -mQTLs (9,932 from cases+controls, 264 from cases and 695 from controls) were enriched in GWAS-identified genetic variants for the above disorders. -eQTLs from AUD cases were mapped to morphine addiction-related genes. PFC -eQTLs/-mQTLs influence gene expression/DNA methylation patterns, thus increasing the disease risk.
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http://dx.doi.org/10.2217/epi-2019-0270DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7607393PMC
May 2020

Association of OPRM1 Functional Coding Variant With Opioid Use Disorder: A Genome-Wide Association Study.

JAMA Psychiatry 2020 Oct;77(10):1072-1080

Department of Psychiatry, Yale School of Medicine, New Haven, Connecticut.

Importance: With the current opioid crisis, it is important to improve understanding of the biological mechanisms of opioid use disorder (OUD).

Objectives: To detect genetic risk variants for OUD and determine genetic correlations and causal association with OUD and other traits.

Design, Setting, And Participants: A genome-wide association study of electronic health record-defined OUD in the Million Veteran Program sample was conducted, comprising 8529 affected European American individuals and 71 200 opioid-exposed European American controls (defined by electronic health record trajectory analysis) and 4032 affected African American individuals and 26 029 opioid-exposed African American controls. Participants were enrolled from January 10, 2011, to May 21, 2018, with electronic health record data for OUD diagnosis from October 1, 1999, to February 7, 2018. Million Veteran Program results and additional OUD case-control genome-wide association study results from the Yale-Penn and Study of Addiction: Genetics and Environment samples were meta-analyzed (total numbers: European American individuals, 10 544 OUD cases and 72 163 opioid-exposed controls; African American individuals, 5212 cases and 26 876 controls). Data on Yale-Penn participants were collected from February 14, 1999, to April 1, 2017, and data on Study of Addiction: Genetics and Environment participants were collected from 1990 to 2007. The key result was replicated in 2 independent cohorts: proxy-phenotype buprenorphine treatment in the UK Biobank and newly genotyped Yale-Penn participants. Genetic correlations between OUD and other traits were tested, and mendelian randomization analysis was conducted to identify potential causal associations.

Main Outcomes And Measures: Main outcomes were International Classification of Diseases, Ninth Revision-diagnosed OUD or International Statistical Classification of Diseases and Related Health Problems, Tenth Revision-diagnosed OUD (Million Veteran Program), and DSM-IV-defined opioid dependence (Yale-Penn and Study of Addiction: Genetics and Environment).

Results: A total of 114 759 individuals (101 016 men [88%]; mean [SD] age, 60.1 [12.8] years) were included. In 82 707 European American individuals, a functional coding variant (rs1799971, encoding Asn40Asp) in OPRM1 (μ-opioid receptor gene, the main biological target for opioid drugs; OMIM 600018) reached genome-wide significance (G allele: β = -0.066 [SE = 0.012]; P = 1.51 × 10-8). The finding was replicated in 2 independent samples. Single-nucleotide polymorphism-based heritability of OUD was 11.3% (SE = 1.8%). Opioid use disorder was genetically correlated with 83 traits, including multiple substance use traits, psychiatric illnesses, cognitive performance, and others. Mendelian randomization analysis revealed the following associations with OUD: risk of tobacco smoking, depression, neuroticism, worry neuroticism subcluster, and cognitive performance. No genome-wide significant association was detected for African American individuals or in transpopulation meta-analysis.

Conclusions And Relevance: This genome-wide meta-analysis identified a significant association of OUD with an OPRM1 variant, which was replicated in 2 independent samples. Post-genome-wide association study analysis revealed associated pleiotropic characteristics. Recruitment of additional individuals with OUD for future studies-especially those of non-European ancestry-is a crucial next step in identifying additional significant risk loci.
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http://dx.doi.org/10.1001/jamapsychiatry.2020.1206DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7270886PMC
October 2020

Leveraging genome-wide data to investigate differences between opioid use vs. opioid dependence in 41,176 individuals from the Psychiatric Genomics Consortium.

Mol Psychiatry 2020 08 26;25(8):1673-1687. Epub 2020 Feb 26.

Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, IN, USA.

To provide insights into the biology of opioid dependence (OD) and opioid use (i.e., exposure, OE), we completed a genome-wide analysis comparing 4503 OD cases, 4173 opioid-exposed controls, and 32,500 opioid-unexposed controls, including participants of European and African descent (EUR and AFR, respectively). Among the variants identified, rs9291211 was associated with OE (exposed vs. unexposed controls; EUR z = -5.39, p = 7.2 × 10). This variant regulates the transcriptomic profiles of SLC30A9 and BEND4 in multiple brain tissues and was previously associated with depression, alcohol consumption, and neuroticism. A phenome-wide scan of rs9291211 in the UK Biobank (N > 360,000) found association of this variant with propensity to use dietary supplements (p = 1.68 × 10). With respect to the same OE phenotype in the gene-based analysis, we identified SDCCAG8 (EUR + AFR z = 4.69, p = 10), which was previously associated with educational attainment, risk-taking behaviors, and schizophrenia. In addition, rs201123820 showed a genome-wide significant difference between OD cases and unexposed controls (AFR z = 5.55, p = 2.9 × 10) and a significant association with musculoskeletal disorders in the UK Biobank (p = 4.88 × 10). A polygenic risk score (PRS) based on a GWAS of risk-tolerance (n = 466,571) was positively associated with OD (OD vs. unexposed controls, p = 8.1 × 10; OD cases vs. exposed controls, p = 0.054) and OE (exposed vs. unexposed controls, p = 3.6 × 10). A PRS based on a GWAS of neuroticism (n = 390,278) was positively associated with OD (OD vs. unexposed controls, p = 3.2 × 10; OD vs. exposed controls, p = 0.002) but not with OE (p = 0.67). Our analyses highlight the difference between dependence and exposure and the importance of considering the definition of controls in studies of addiction.
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http://dx.doi.org/10.1038/s41380-020-0677-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7392789PMC
August 2020

Genomic influences on self-reported childhood maltreatment.

Transl Psychiatry 2020 01 27;10(1):38. Epub 2020 Jan 27.

US Army Medical Research and Materiel Command, Fort Detrick, MD, USA.

Childhood maltreatment is highly prevalent and serves as a risk factor for mental and physical disorders. Self-reported childhood maltreatment appears heritable, but the specific genetic influences on this phenotype are largely unknown. The aims of this study were to (1) identify genetic variation associated with self-reported childhood maltreatment, (2) estimate SNP-based heritability (h), (3) assess predictive value of polygenic risk scores (PRS) for childhood maltreatment, and (4) quantify genetic overlap of childhood maltreatment with mental and physical health-related phenotypes, and condition the top hits from our analyses when such overlap is present. Genome-wide association analysis for childhood maltreatment was undertaken, using a discovery sample from the UK Biobank (UKBB) (n = 124,000) and a replication sample from the Psychiatric Genomics Consortium-posttraumatic stress disorder group (PGC-PTSD) (n = 26,290). h for childhood maltreatment and genetic correlations with mental/physical health traits were calculated using linkage disequilibrium score regression. PRS was calculated using PRSice and mtCOJO was used to perform conditional analysis. Two genome-wide significant loci associated with childhood maltreatment (rs142346759, p = 4.35 × 10, FOXP1; rs10262462, p = 3.24 × 10, FOXP2) were identified in the discovery dataset but were not replicated in PGC-PTSD. h for childhood maltreatment was ~6% and the PRS derived from the UKBB was significantly predictive of childhood maltreatment in PGC-PTSD (r = 0.0025; p = 1.8 × 10). The most significant genetic correlation of childhood maltreatment was with depressive symptoms (r = 0.70, p = 4.65 × 10), although we show evidence that our top hits may be specific to childhood maltreatment. This is the first large-scale genetic study to identify specific variants associated with self-reported childhood maltreatment. Speculatively, FOXP genes might influence externalizing traits and so be relevant to childhood maltreatment. Alternatively, these variants may be associated with a greater likelihood of reporting maltreatment. A clearer understanding of the genetic relationships of childhood maltreatment, including particular abuse subtypes, with a range of phenotypes, may ultimately be useful in in developing targeted treatment and prevention strategies.
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http://dx.doi.org/10.1038/s41398-020-0706-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7026037PMC
January 2020

Shared genetic risk between eating disorder- and substance-use-related phenotypes: Evidence from genome-wide association studies.

Addict Biol 2021 01 16;26(1):e12880. Epub 2020 Feb 16.

Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, RWTH Aachen University, Aachen, Germany.

Eating disorders and substance use disorders frequently co-occur. Twin studies reveal shared genetic variance between liabilities to eating disorders and substance use, with the strongest associations between symptoms of bulimia nervosa and problem alcohol use (genetic correlation [r ], twin-based = 0.23-0.53). We estimated the genetic correlation between eating disorder and substance use and disorder phenotypes using data from genome-wide association studies (GWAS). Four eating disorder phenotypes (anorexia nervosa [AN], AN with binge eating, AN without binge eating, and a bulimia nervosa factor score), and eight substance-use-related phenotypes (drinks per week, alcohol use disorder [AUD], smoking initiation, current smoking, cigarettes per day, nicotine dependence, cannabis initiation, and cannabis use disorder) from eight studies were included. Significant genetic correlations were adjusted for variants associated with major depressive disorder and schizophrenia. Total study sample sizes per phenotype ranged from ~2400 to ~537 000 individuals. We used linkage disequilibrium score regression to calculate single nucleotide polymorphism-based genetic correlations between eating disorder- and substance-use-related phenotypes. Significant positive genetic associations emerged between AUD and AN (r = 0.18; false discovery rate q = 0.0006), cannabis initiation and AN (r = 0.23; q < 0.0001), and cannabis initiation and AN with binge eating (r = 0.27; q = 0.0016). Conversely, significant negative genetic correlations were observed between three nondiagnostic smoking phenotypes (smoking initiation, current smoking, and cigarettes per day) and AN without binge eating (r = -0.19 to -0.23; qs < 0.04). The genetic correlation between AUD and AN was no longer significant after co-varying for major depressive disorder loci. The patterns of association between eating disorder- and substance-use-related phenotypes highlights the potentially complex and substance-specific relationships among these behaviors.
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http://dx.doi.org/10.1111/adb.12880DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7429266PMC
January 2021

An analysis of the effect of mu-opioid receptor gene (OPRM1) promoter region DNA methylation on the response of naltrexone treatment of alcohol dependence.

Pharmacogenomics J 2020 10 7;20(5):672-680. Epub 2020 Feb 7.

Department of Psychiatry, Boston University School of Medicine, Boston, MA, USA.

This study explored the effect of OPRM1 promoter region DNA methylation on the outcome of treatment with the opioid antagonist naltrexone (NTX) for alcohol dependence (AD). Ninety-three patients with DSM-IV AD [41 African Americans (AAs) and 52 European Americans (EAs)] received double-blind treatment with NTX or placebo for at least three months. Relapse to heavy drinking was assessed during the first 13 weeks of the trial. Peripheral blood methylation levels of 33 CpG units in the OPRM1 promoter region were quantified using Sequenom EpiTYPER technology. Bayesian logistic regression was used to analyze the effects of NTX treatment, CpG methylation, CpG methylation × NTX treatment, and age on AD relapse. The Random Forest machine learning algorithm was applied to select AD relapse predictors. No significant effect of individual OPRM1 promoter CpG units on AD relapse was observed in either AAs or EAs. Age was significantly associated with AD relapse in EAs, among whom older subjects had a lower relapse rate. Random forest analyses revealed that the prediction rate for AD relapse reached 66.0% with five top variables (age and four CpG units; ranked by their importance to AD relapse) in the prediction model. These findings suggest that methylation levels of individual OPRM1 promoter CpG units do not contribute significantly to inter-individual variation in NTX response. However, the age of subjects in combination with a cluster of specific OPRM1 promoter CpG units may affect NTX treatment outcome. Additional studies of OPRM1 DNA methylation changes during and after NTX treatment of AD are needed.
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http://dx.doi.org/10.1038/s41397-020-0158-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7415483PMC
October 2020

Exceptionally low likelihood of Alzheimer's dementia in APOE2 homozygotes from a 5,000-person neuropathological study.

Nat Commun 2020 02 3;11(1):667. Epub 2020 Feb 3.

Department of Epidemiology, University of Washington, 1959 NE Pacific Street, Seattle, WA, 98195, USA.

Each additional copy of the apolipoprotein E4 (APOE4) allele is associated with a higher risk of Alzheimer's dementia, while the APOE2 allele is associated with a lower risk of Alzheimer's dementia, it is not yet known whether APOE2 homozygotes have a particularly low risk. We generated Alzheimer's dementia odds ratios and other findings in more than 5,000 clinically characterized and neuropathologically characterized Alzheimer's dementia cases and controls. APOE2/2 was associated with a low Alzheimer's dementia odds ratios compared to APOE2/3 and 3/3, and an exceptionally low odds ratio compared to APOE4/4, and the impact of APOE2 and APOE4 gene dose was significantly greater in the neuropathologically confirmed group than in more than 24,000 neuropathologically unconfirmed cases and controls. Finding and targeting the factors by which APOE and its variants influence Alzheimer's disease could have a major impact on the understanding, treatment and prevention of the disease.
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http://dx.doi.org/10.1038/s41467-019-14279-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6997393PMC
February 2020

Genome-Wide Association Study of Opioid Cessation.

J Clin Med 2020 Jan 9;9(1). Epub 2020 Jan 9.

Department of Medicine (Biomedical Genetics), Boston University School of Medicine, Boston, MA 02118, USA.

The United States is experiencing an epidemic of opioid use disorder (OUD) and overdose-related deaths. However, the genetic basis for the ability to discontinue opioid use has not been investigated. We performed a genome-wide association study (GWAS) of opioid cessation (defined as abstinence from illicit opioids for >1 year or <6 months before the interview date) in 1130 African American (AA) and 2919 European ancestry (EA) participants recruited for genetic studies of substance use disorders and who met lifetime Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) criteria for OUD. Association tests performed separately within each ethnic group were combined by meta-analysis with results obtained from the Comorbidity and Trauma Study. Although there were no genome-wide significant associations, we found suggestive associations with nine independent loci, including three which are biologically relevant: rs4740988 in ( = 2.24 × 10), rs36098404 in ( = 2.24 × 10), and rs592026 in ( = 6.53 × 10). Significant pathways identified in persons of European ancestry (EA) are related to vitamin D metabolism ( = 3.79 × 10) and fibroblast growth factor (FGF) signaling ( = 2.39 × 10). UK Biobank traits including smoking and drinking cessation and chronic back pain were significantly associated with opioid cessation using GWAS-derived polygenic risk scores. These results provide evidence for genetic influences on opioid cessation, suggest genetic overlap with other relevant traits, and may indicate potential novel therapeutic targets for OUD.
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http://dx.doi.org/10.3390/jcm9010180DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7019731PMC
January 2020

A regulatory variant of CHRM3 is associated with cannabis-induced hallucinations in European Americans.

Transl Psychiatry 2019 11 18;9(1):309. Epub 2019 Nov 18.

Division of Human Genetics, Department of Psychiatry, VA CT Healthcare Center, Yale University School of Medicine, New Haven, CT, USA.

Cannabis, the most widely used illicit drug, can induce hallucinations. Our understanding of the biology of cannabis-induced hallucinations (Ca-HL) is limited. We used the Semi-Structured Assessment for Drug Dependence and Alcoholism (SSADDA) to identify cannabis-induced hallucinations (Ca-HL) among long-term cannabis users (used cannabis ≥1 year and ≥100 times). A genome-wide association study (GWAS) was conducted by analyzing European Americans (EAs) and African Americans (AAs) in Yale-Penn 1 and 2 cohorts individually, then meta-analyzing the two cohorts within population. In the meta-analysis of Yale-Penn EAs (n = 1917), one genome-wide significant (GWS) signal emerged at the CHRM3 locus, represented by rs115455482 (P = 1.66 × 10), rs74722579 (P = 2.81 × 10), and rs1938228 (P = 1.57 × 10); signals were GWS in Yale-Penn 1 EAs (n = 1092) and nominally significant in Yale-Penn 2 EAs (n = 825). Two SNPs, rs115455482 and rs74722579, were available from the Collaborative Study on the Genetics of Alcoholism data (COGA; 3630 long-term cannabis users). The signals did not replicate, but when meta-analyzing Yale-Penn and COGA EAs, the two SNPs' association signals were increased (meta-P-values 1.32 × 10 and 2.60 × 10, respectively; n = 4291). There were no significant findings in AAs, but in the AA meta-analysis (n = 3624), nominal significance was seen for rs74722579. The rs115455482*T risk allele was associated with lower CHRM3 expression in the thalamus. CHRM3 was co-expressed with three psychosis risk genes (GABAG2, CHRNA4, and HRH3) in the thalamus and other human brain tissues and mouse GABAergic neurons. This work provides strong evidence for the association of CHRM3 with Ca-HL and provides insight into the potential involvement of thalamus for this trait.
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http://dx.doi.org/10.1038/s41398-019-0639-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6861240PMC
November 2019

International meta-analysis of PTSD genome-wide association studies identifies sex- and ancestry-specific genetic risk loci.

Nat Commun 2019 10 8;10(1):4558. Epub 2019 Oct 8.

Durham VA Medical Center, Research, Durham, NC, USA.

The risk of posttraumatic stress disorder (PTSD) following trauma is heritable, but robust common variants have yet to be identified. In a multi-ethnic cohort including over 30,000 PTSD cases and 170,000 controls we conduct a genome-wide association study of PTSD. We demonstrate SNP-based heritability estimates of 5-20%, varying by sex. Three genome-wide significant loci are identified, 2 in European and 1 in African-ancestry analyses. Analyses stratified by sex implicate 3 additional loci in men. Along with other novel genes and non-coding RNAs, a Parkinson's disease gene involved in dopamine regulation, PARK2, is associated with PTSD. Finally, we demonstrate that polygenic risk for PTSD is significantly predictive of re-experiencing symptoms in the Million Veteran Program dataset, although specific loci did not replicate. These results demonstrate the role of genetic variation in the biology of risk for PTSD and highlight the necessity of conducting sex-stratified analyses and expanding GWAS beyond European ancestry populations.
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http://dx.doi.org/10.1038/s41467-019-12576-wDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6783435PMC
October 2019

Promoter Polymorphism-219T/G is an Effect Modifier of the Influence of ε4 on Alzheimer's Disease Risk in a Multiracial Sample.

J Clin Med 2019 Aug 16;8(8). Epub 2019 Aug 16.

Department of Molecular Genetics, Brain Research Institute, Niigata University, Niigata 951-8585, Japan.

Variants in the gene region may explain ethnic differences in the association of Alzheimer's disease (AD) with ε4. Ethnic differences in allele frequencies for three region SNPs (single nucleotide polymorphisms) were identified and tested for association in 19,398 East Asians (EastA), including Koreans and Japanese, 15,836 European ancestry (EuroA) individuals, and 4985 African Americans, and with brain imaging measures of cortical atrophy in sub-samples of Koreans and EuroAs. Among ε4/ε4 individuals, AD risk increased substantially in a dose-dependent manner with the number of promoter SNP rs405509 alleles in EastAs : OR (odds ratio) = 27.02, = 8.80 × 10; : OR = 15.87, = 2.62 × 10) and EuroAs (: OR = 18.13, = 2.69 × 10; : OR = 12.63, = 3.44 × 10), and rs405509- homozygotes had a younger onset and more severe cortical atrophy than those with -allele. Functional experiments using promoter fragments demonstrated that lowered expression in human brain and serum. The modifying effect of rs405509 genotype explained much of the ethnic variability in the AD/ε4 association, and increasing expression might lower AD risk among ε4 homozygotes.
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http://dx.doi.org/10.3390/jcm8081236DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6723529PMC
August 2019

A systems biology approach towards understanding and treating non-neovascular age-related macular degeneration.

Nat Commun 2019 07 26;10(1):3347. Epub 2019 Jul 26.

Departments of Medicine (Biomedical Genetics), Neurology, Ophthalmology, Epidemiology, and Biostatistics, Boston University Schools of Medicine and Public Health, Boston, 02118, MA, USA.

Age-related macular degeneration (AMD) is the most common cause of blindness among the elderly in the developed world. While treatment is effective for the neovascular or "wet" form of AMD, no therapy is successful for the non-neovascular or "dry" form. Here we discuss the current knowledge on dry AMD pathobiology and propose future research directions that would expedite the development of new treatments. In our view, these should emphasize system biology approaches that integrate omic, pharmacological, and clinical data into mathematical models that can predict disease onset and progression, identify biomarkers, establish disease causing mechanisms, and monitor response to therapy.
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http://dx.doi.org/10.1038/s41467-019-11262-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6659646PMC
July 2019

Analysis of Whole-Exome Sequencing Data for Alzheimer Disease Stratified by APOE Genotype.

JAMA Neurol 2019 Sep;76(9):1099-1108

Department of Medicine (Biomedical Genetics), Boston University Schools of Medicine and Public Health, Boston, Massachusetts.

Importance: Previous genome-wide association studies of common variants identified associations for Alzheimer disease (AD) loci evident only among individuals with particular APOE alleles.

Objective: To identify APOE genotype-dependent associations with infrequent and rare variants using whole-exome sequencing.

Design, Setting, And Participants: The discovery stage included 10 441 non-Hispanic white participants in the Alzheimer Disease Sequencing Project. Replication was sought in 2 independent, whole-exome sequencing data sets (1766 patients with AD, 2906 without AD [controls]) and a chip-based genotype imputation data set (8728 patients with AD, 9808 controls). Bioinformatics and functional analyses were conducted using clinical, cognitive, neuropathologic, whole-exome sequencing, and gene expression data obtained from a longitudinal cohort sample including 402 patients with AD and 647 controls. Data were analyzed between March 2017 and September 2018.

Main Outcomes And Measures: Score, Firth, and sequence kernel association tests were used to test the association of AD risk with individual variants and genes in subgroups of APOE ε4 carriers and noncarriers. Results with P ≤ 1 × 10-5 were further evaluated in the replication data sets and combined by meta-analysis.

Results: Among 3145 patients with AD and 4213 controls lacking ε4 (mean [SD] age, 83.4 [7.6] years; 4363 [59.3.%] women), novel genome-wide significant associations were obtained in the discovery sample with rs536940594 in AC099552 (odds ratio [OR], 88.0; 95% CI, 9.08-852.0; P = 2.22 × 10-7) and rs138412600 in GPAA1 (OR, 1.78; 95% CI, 1.44-2.2; meta-P = 7.81 × 10-8). GPAA1 was also associated with expression in the brain of GPAA1 (β = -0.08; P = .03) and its repressive transcription factor, FOXG1 (β = 0.13; P = .003), and global cognition function (β = -0.53; P = .009). Significant gene-wide associations (threshold P ≤ 6.35 × 10-7) were observed for OR8G5 (P = 4.67 × 10-7), IGHV3-7 (P = 9.75 × 10-16), and SLC24A3 (P = 2.67 × 10-12) in 2377 patients with AD and 706 controls with ε4 (mean [SD] age, 75.2 [9.6] years; 1668 [54.1%] women).

Conclusions And Relevance: The study identified multiple possible novel associations for AD with individual and aggregated rare variants in groups of individuals with and without APOE ε4 alleles that reinforce known and suggest additional pathways leading to AD.
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http://dx.doi.org/10.1001/jamaneurol.2019.1456DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6563544PMC
September 2019

CpG-related SNPs in the MS4A region have a dose-dependent effect on risk of late-onset Alzheimer disease.

Aging Cell 2019 08 29;18(4):e12964. Epub 2019 May 29.

Department of Biostatistics, Boston University School of Public Health, Boston, Massachusetts.

CpG-related single nucleotide polymorphisms (CGS) have the potential to perturb DNA methylation; however, their effects on Alzheimer disease (AD) risk have not been evaluated systematically. We conducted a genome-wide association study using a sliding-window approach to measure the combined effects of CGSes on AD risk in a discovery sample of 24 European ancestry cohorts (12,181 cases, 12,601 controls) from the Alzheimer's Disease Genetics Consortium (ADGC) and replication sample of seven European ancestry cohorts (7,554 cases, 27,382 controls) from the International Genomics of Alzheimer's Project (IGAP). The potential functional relevance of significant associations was evaluated by analysis of methylation and expression levels in brain tissue of the Religious Orders Study and the Rush Memory and Aging Project (ROSMAP), and in whole blood of Framingham Heart Study participants (FHS). Genome-wide significant (p < 5 × 10 ) associations were identified with 171 1.0 kb-length windows spanning 932 kb in the APOE region (top p < 2.2 × 10 ), five windows at BIN1 (top p = 1.3 × 10 ), two windows at MS4A6A (top p = 2.7 × 10 ), two windows near MS4A4A (top p = 6.4 × 10 ), and one window at PICALM (p = 6.3 × 10 ). The total number of CGS-derived CpG dinucleotides in the window near MS4A4A was associated with AD risk (p = 2.67 × 10 ), brain DNA methylation (p = 2.15 × 10 ), and gene expression in brain (p = 0.03) and blood (p = 2.53 × 10 ). Pathway analysis of the genes responsive to changes in the methylation quantitative trait locus signal at MS4A4A (cg14750746) showed an enrichment of methyltransferase functions. We confirm the importance of CGS in AD and the potential for creating a functional CpG dosage-derived genetic score to predict AD risk.
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http://dx.doi.org/10.1111/acel.12964DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6612647PMC
August 2019