Amanda Partch

The role of TREM2 R47H as a risk factor for Alzheimer's disease, frontotemporal lobar degeneration, amyotrophic lateral sclerosis, and Parkinson's disease

A rare variant in TREM2 (p.R47H, rs75932628) was recently reported to increase the risk of Alzheimers disease (AD) and, subsequently, other neurodegenerative diseases, i.e. frontotemporal lobar degeneration (FTLD), amyotrophic lateral sclerosis (ALS), and Parkinsons disease (PD). Here we comprehensively assessed TREM2 rs75932628 for association with these diseases in a total of 19,940 previously untyped subjects of European descent. These data were combined with those from 28 published data sets by meta‐analysis. Furthermore, we tested whether rs75932628 shows association with amyloid beta (Aβ42) and total‐tau protein levels in the cerebrospinal fluid (CSF) of 828 individuals with AD or mild cognitive impairment. Our data show that rs75932628 is highly significantly associated with the risk of AD across 24,086 AD cases and 148,993 controls of European descent (odds ratio or OR = 2.71, P = 4.67 × 10−25). No consistent evidence for association was found between this marker and the risk of FTLD (OR = 2.24, P = .0113 across 2673 cases/9283 controls), PD (OR = 1.36, P = .0767 across 8311 cases/79,938 controls) and ALS (OR = 1.41, P = .198 across 5544 cases/7072 controls). Furthermore, carriers of the rs75932628 risk allele showed significantly increased levels of CSF‐total‐tau (P = .0110) but not Aβ42 suggesting that TREM2s role in AD may involve tau dysfunction.

Reassessment of Risk Genotypes (GRN, TMEM106B, and ABCC9 Variants) Associated With Hippocampal Sclerosis of Aging Pathology

Abstract Hippocampal sclerosis of aging (HS-Aging) is a common high-morbidity neurodegenerative condition in elderly persons. To understand the risk factors for HS-Aging, we analyzed data from the Alzheimer’s Disease Genetics Consortium and correlated the data with clinical and pathologic information from the National Alzheimer’s Coordinating Center database. Overall, 268 research volunteers with HS-Aging and 2,957 controls were included; detailed neuropathologic data were available for all. The study focused on single-nucleotide polymorphisms previously associated with HS-Aging risk: rs5848 (GRN), rs1990622 (TMEM106B), and rs704180 (ABCC9). Analyses of a subsample that was not previously evaluated (51 HS-Aging cases and 561 controls) replicated the associations of previously identified HS-Aging risk alleles. To test for evidence of gene-gene interactions and genotype-phenotype relationships, pooled data were analyzed. The risk for HS-Aging diagnosis associated with these genetic polymorphisms was not secondary to an association with either Alzheimer disease or dementia with Lewy body neuropathologic changes. The presence of multiple risk genotypes was associated with a trend for additive risk for HS-Aging pathology. We conclude that multiple genes play important roles in HS-Aging, which is a distinctive neurodegenerative disease of aging.

ALZHEIMER'S DISEASE SEQUENCING PROJECT: SEARCH FOR ALZHEIMER'S DISEASE RESILIENCE GENES THAT MAY MODIFY DISEASE SUSCEPTIBILITY IN SPECIFIC APOE GENOTYPE BACKGROUNDS

not available. EC-01-04 PHYSIOLOGICAL SUBSTRATES OF BACE1 AND ADAM10: SAFETY ISSUES OR BIOMARKERS? Stefan Lichtenthaler, Technical University of Munich, Munich, Germany; German Center for Neurodegenerative Diseases (DZNE), Munich, Germany.. Contact e-mail: Stefan.Lichtenthaler@dzne.de Background: The beta-secretase BACE1 is a major drug target in Alzheimer’s disease (AD), but also has other functions, e.g. in myelination and axon targeting. BACE1-deficient mice have additional phenotypes in the brain and several BACE1 substrates, referred to as the BACE1 degradome, are emerging in the CNS. This raises the possibility that therapeutic BACE1 inhibition may have mechanism-based side-effects. Additionally, most BACE1 inhibitors also block the homologous protease BACE2 and, thus, may interfere with BACE2 function. Methods: We developed methods for whole proteome analysis of murine tissue, including CSF Results: We used the novel methods to identify BACE1 substrate candidates in murine CSF, but also in neurons and brains. Selected substrate candidates were validated and functionally and mechanistically characterized. Two of the candidates are seizure protein 6 (SEZ6) and SEZ6-like (SEZ6L), which control neurite outgrowth and synapse formation. Both proteins were validated as BACE1 substrates in vitro and in vivo. In CSF, SEZ6 and SEZ6Lwere found to be suitable markers for measuring BACE1 inhibition in vivo. Conclusions: BACE1 has broad functions in the CNS. The presentation will discuss the implication of the substrates a) for the safety of BACE1 inhibitors and b) for the use as companion diagnostics to monitor BACE inhibition in vivo. SUNDAY, JULY 24, 2016 FEATURED RESEARCH SESSIONS F1-01 THE ALZHEIMER’S DISEASE SEQUENCING PROJECT (ADSP): GENE DISCOVERY IN ACTION F1-01-01 STRUCTURALVARIATION (SV) IN HETEROGENOUS WHOLE-GENOME SEQUENCING DATA FROM 111 FAMILIES AT RISK FOR ALZHEIMER DISEASE: ALZHEIMER DISEASE SEQUENCING PROJECT SV STUDY Li Charlie Xia, Stanford University, Stanford, CA, USA; University of Pennsylvania, Philadelphia, PA, USA. Contact e-mail: lixia@stanford.edu Background: The Alzheimer Disease Sequencing Project (ADSP) is a national initiative to identify novel genetic variants involved in determining risk of late-onset Alzheimer disease (AD). Methods: Structural variation was characterized in 111 families of multiple ethnicities comprising 578 individuals diagnosed with or at risk for AD. We developed a statistical framework that leverages pedigree information to assess accuracy and optimize structural variant (SV) calls. The kinship coefficient was used to filter SVs showing excess heterozygosity. We also formulated a metric called the D-score which is an outgroup-based measure of sib-sharing to filter SVs identified by calling algorithms that detect insertion and deletion breakpoints, but do not render genotypes. These metrics also permitted assessment of reliability of individual calling programs for various SV sizes. An in silico procedure was devised to “spike-in” SVs of varying purity into real sequenced libraries, accommodating multi-library designs, and applied it to three samples that were sequenced at all three centers. This comprehensive QC process allowed benchmarking SV callers across the widely differing libraries and combining these callers in a library-specific way for improved specificity and sensitivity. Candidate SV regions were further refined using an ensemble of 12 SV callers with local assembly to provide precise breakpoints for subsequent calling of genotypes. Results:We identified a high-confidence set of deletions, insertions, and complex variants larger than 20 base pairs (bp) genotyped across all 578 individuals. These variants were prioritized based on predicted functional impact and overlap with known AD genes and linkage regions. Thus far, we detected, and confirmed by sequencing, a 44 bp ABCA7 deletion in 11 members (all have AD) of 5 of 67 CaribbeanHispanic families. This finding is consistent with our recent AD association finding of this deletion in a sample containing >2,800 African Americans which results in a frameshift and truncating mutation that could interfere with protein function. Conclusions: A carefully developed pipeline for detecting, genotyping, and filtering SVs from family-based whole genome sequence data permitted discovery of a robust association of AD risk with a rare 44 bp deletion in ABCA7. Amore comprehensive analysis of these data is underway. F1-01-02 ALZHEIMER’S DISEASE SEQUENCING PROJECT: SEARCH FOR ALZHEIMER’S DISEASE RESILIENCE GENES THAT MAY MODIFY DISEASE SUSCEPTIBILITY IN SPECIFIC APOE GENOTYPE BACKGROUNDS Eduardo Marcora, Alan E. Renton, Gary W. Beecham, Eric Boerwinkle, Laura Cantwell, Carlos Cruchaga, Rebecca Cweibel, Adam Felsenfeld, Myriam Fornage, Manav Kapoor, Keoni Kauwe, Mugdha Khaladkar, Dan Kobolt, Yiyi Ma, Richard Mayeux, Marilyn Miller, Adam C. Naj, Amanda B. Partch, Margaret A. Pericak-Vance, Gerard D. Schellenberg, Sudha Seshadri, Badri N. Vardarajan, Li-San Wang, Joshua C. Bis, Lindsay A. Farrer, Alison M. Goate, 1 Icahn School of Medicine at Mount Sinai, New York, NY, USA; 2 University of Miami Miller School of Medicine, Miami, FL, USA; Baylor College of Medicine, Houston, TX, USA; University of Texas Health Science Center at Houston, Houston, TX, USA; 5 University of Pennsylvania, Philadelphia, PA, USA; 6 Washington University in St. Louis, Saint Louis, MO, USA; Washington University School of Medicine, St. Louis, MO, USA; Knight Alzheimer Disease Center, St. Louis, MO, USA; Division of Genome Sciences, National HumanGenome Research Institute, Bethesda,MD, USA; 10 University of Texas Health Science Center at Houston McGovern Medical School, Houston, TX, USA; Brigham Young University, Provo, UT, USA; Washington University in St. Louis, St. Louis, MO, USA; Washington University, St. Louis, MO, USA; 14 The Genome Institute, Washington University in St. Louis, St. Louis, MO, USA; Boston University, Boston, MA, USA; Columbia University, New York, NY, USA; Division of Neuroscience, National Institute on Aging, Bethesda, MD, USA; 18 University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA; The National Heart, Lung, and Blood Institute’s Framingham Heart Study, Framingham, MA, USA; Boston University School of Medicine, Boston, MA, USA; 21 University of Washington, Seattle, WA, USA. Contact e-mail: edoardo.marcora@mssm.edu Background:Common variation at the APOE locus is the strongest known genetic risk factor for Alzheimer’s disease (AD). Podium Presentations: Sunday, July 24, 2016 P162

Multiple deletion copy number variants (CNVs) are associated with late-onset Alzheimer's disease: The Alzheimer’s disease genetics consortium

Background:Alzheimer’s disease (AD) is characterized by progressive neuropathology and cognitive decline. Although the neuropathological manifestation of AD is well characterized in postmortem brain, little is known about the underlying risk factors or mechanism(s) involved in disease progression. We recently published the first epigenome-wide association studies (EWAS), demonstrating methylomic variation in AD brain and blood (Lunnon et al., 2014), with the most notable differences occurring in regions of the brain characterised by extensive neuropathology. Following on from these studies, we describe a network approach to identify modules of co-methylated loci associated with amyloid and tau burden using DNA from multiple brain regions in a cohort of 144 samples. Methods: DNA was extracted from 100mg tissue from a cohort of 144 individuals from the Mount Sinai NIH Brain and Tissue Repository (NBTR), with two brain regions (Prefrontal cortex-PFC and Superior temporal gyrus-STG) obtained from each individual. Genomic DNA was bisulfite treated using the Zymo EZ DNA methylation kit and samples were assessed using the Illumina Infinium Human Methylation 450K BeadChip. Following data normalisation and stringent quality control, we identifiedmethylomic variation associatedwith quantitativemeasures of neuropathology (amyloid/tau) using linear models, whilst controlling for the effects of age and gender. We used the R package “WGCNA” to identify groups of co-methylated genes that were associated with (a) neuropathological measures and (b) genetic variants associated with AD from recent large meta-analyses. Results: We identified many differentially methylate positions (DMPs) associated with disease in both the PFC and STG, replicating many of our previous findings. The strongest results were found with amyloid burden and braak staging, where we observed DMPs located in and near previously identified genes containing risk variants, including APOE. UsingWGCNA, we also identified multiple modules of co-methylated loci characterised by consistent associations with disease status and neuropathology measures, as well as polygenic risk status. Conclusions:This study provides further evidence for a role of epigenomic dysfunction in AD, identifying networks of co-methylated loci associated withvarious neuropathological traits. We demonstrate strong evidence for an interaction between genotype and DNA methylation at loci previously implicated in genetic studies of AD.