Age-related macular degeneration (AMD) is a common cause of blindness in older individuals. To accelerate understanding of AMD biology and help design new therapies, we executed a collaborative genomewide association study, examining >17,100 advanced AMD cases and >60,000 controls of European and Asian ancestry. We identified 19 genomic loci associated with AMD with p<5×10−8 and enriched for genes involved in regulation of complement activity, lipid metabolism, extracellular matrix remodeling and angiogenesis. Our results include 7 loci reaching p<5×10−8 for the first time, near the genes COL8A1/FILIP1L, IER3/DDR1, SLC16A8, TGFBR1, RAD51B, ADAMTS9/MIR548A2, and B3GALTL. A genetic risk score combining SNPs from all loci displayed similar good ability to distinguish cases and controls in all samples examined. Our findings provide new directions for biological, genetic and therapeutic studies of AMD.

We executed a genome-wide association scan for age-related macular degeneration (AMD) in 2,157 cases and 1,150 controls. Our results validate AMD susceptibility loci near CFH (P < 10 −75), ARMS2 (P < 10 −59), C2/CFB (P < 10 −20), C3 (P < 10 −9 ), and CFI (P < 10 −6). We compared our top findings with the Tufts/Massachusetts General Hospital genome-wide association study of advanced AMD (821 cases, 1,709 controls) and genotyped 30 promising markers in additional individuals (up to 7,749 cases and 4,625 controls). With these data, we identified a susceptibility locus near TIMP3 (overall P = 1.1 × 10), a metalloproteinase involved in degradation of the extracellular matrix and previously implicated in early-onset maculopathy. In addition, our data revealed strong association signals with alleles at two loci (LIPC, P = 1.3 × 10 −7; CETP, P = 7.4 × 10 −7 ) that were previously associated with high-density lipoprotein cholesterol (HDL-c) levels in blood. Consistent with the hypothesis that HDL metabolism is associated with AMD pathogenesis, we also observed association with AMD of HDL-c-associated alleles near LPL (P = 3.0 × 10 −3) and ABCA1 (P = 5.6 × 10 −4). Multilocus analysis including all susceptibility loci showed that 329 of 331 individuals (99%) with the highest-risk genotypes were cases, and 85% of these had advanced AMD. Our studies extend the catalog of AMD associated loci, help identify individuals at high risk of disease, and provide clues about underlying cellular pathways that should eventually lead to new therapies.genome-wide association study | single nucleotide polymorphism A ge-related macular degeneration (AMD) is a progressive neurodegenerative disease and a common cause of blindness in the elderly population, particularly in developed countries (1). The disease affects primarily the macular region of the retina, which is necessary for sharp central vision. An early hallmark of AMD is the appearance of drusen, which are extracellular deposits of proteins and lipids under the retinal pigment epithelium (RPE). As the disease progresses, drusen grow in size and number. In advanced stages of AMD, atrophy of the RPE (geographic atrophy) and/or development of new blood vessels (neovascularization) result in death of photoreceptors and central vision loss.

Background Atypical variants of Alzheimer’s disease (AD) have been pathologically defined based on the distribution of neurofibrillary tangles; hippocampal sparing (HpSp) AD shows minimal involvement of the hippocampus and limbic predominant (LP) AD shows neurofibrillary tangles restricted to the medial temporal lobe. We aimed to determine whether MRI patterns of atrophy differ across HpSp AD, LP AD and typical AD, and whether imaging could be a useful predictor of pathological subtype during life. Methods In this case-control study, we identified 177 patients who had been prospectively followed in the Mayo Clinic Alzheimer’s Disease Research Center, were demented during life, had AD pathology at autopsy (Braak stage ≥ IV, intermediate-high probability AD) and an antemortem MRI. Cases were assigned to one of three pathological subtypes (HpSp n=19, typical n=125, or LP AD n=33) based on neurofibrillary tangle counts and their ratio in association cortices to hippocampus, without reference to neuronal loss. Voxel-based morphometry and atlas-based parcellation were used to compare patterns of grey matter loss across groups, and to controls. Findings The severity of medial temporal and cortical grey matter atrophy differed across subtypes. The most severe medial temporal atrophy was observed in LP AD, followed by typical AD, and then HpSp AD. Conversely, the most severe cortical atrophy was observed in HpSp AD, followed by typical AD, and then LP AD. A ratio of hippocampal-to-cortical volume provided the best discrimination across all three AD subtypes. The majority of typical AD (98/125;78%) and LP AD (31/33;94%) subjects, but only 8/19 (42%) of the HpSp AD subjects, presented with a dominant amnestic syndrome. Interpretation Patterns of atrophy on MRI differ across the pathological subtypes of AD, suggesting that MR regional volumetrics reliably track the distribution of neurofibrillary tangle pathology and can predict pathological subtype during life. Funding US National Institutes of Health (National Institute on Aging)

The aim of this study was to determine whether the TAR DNA-binding protein of 43kDa (TDP-43) independently has any effect on the clinical and neuroimaging features typically ascribed to Alzheimer’s disease (AD) pathology, and whether TDP-43 pathology could help shed light on the phenomenon of resilient cognition in AD. Three-hundred forty-two subjects pathologically diagnosed with AD were screened for the presence, burden and distribution of TDP-43. All had been classified as cognitively impaired or normal, prior to death. Atlas-based parcellation and voxel-based morphometry were used to assess regional atrophy on MRI. Regression models controlling for age at death, apolipoprotein ε4 and other AD-related pathologies were utilized to explore associations between TDP-43 and cognition or brain atrophy, stratified by Braak stage. Additionally, we determined whether the effects of TDP-43 were mediated by hippocampal sclerosis. One-hundred ninety-five (57%) cases were TDP-positive. After accounting for age, apolipoprotein ε4, and other pathologies, TDP-43 had a strong effect on cognition, memory loss, and medial temporal atrophy in AD. These effects were not mediated by hippocampal sclerosis. TDP-positive subjects were 10× more likely to be cognitively impaired at death compared to TDP-negative subjects. Greater cognitive impairment and medial temporal atrophy were associated with greater TDP-43 burden and more extensive TDP-43 distribution. TDP-43 is an important factor in the manifestation of the clinico-imaging features of AD. TDP-43 also appears to be able to overpower what has been termed resilient brain aging. TDP-43 therefore should be considered a potential therapeutic target for the treatment of AD.

In this study we update the TDP-43 in Alzheimer’s disease staging scheme by assessing the topography of TDP-43 in 193 cases of Alzheimer’s disease, in 14 different brain regions (eight previously described plus six newly reported) and use conditional probability to model the spread of TDP-43 across the 14 brain regions. We show that in addition to the eight original regions we previously reported (amygdala, entorhinal cortex, subiculum, dentate gyrus of the hippocampus, occipitotemporal cortex, inferior temporal cortex, middle frontal cortex and basal ganglia (putamen/globus pallidum)), that TDP-43 is also deposited in the insular cortex, ventral striatum, basal forebrain, substantia nigra, midbrain tectum, and the inferior olive of the medulla oblongata, in Alzheimer’s disease. The conditional probability analysis produced six significantly different stages (P< 0.01), and suggest that TDP-43 deposition begins in the amygdala (stage 1), then moves to entorhinal cortex and subiculum (stage 2), then to the dentate gyrus of the hippocampus and occipitotemporal cortex (stage 3), then insular cortex, ventral striatum, basal forebrain and inferior temporal cortex (stage 4), then substantia nigra, inferior olive and midbrain tectum (stage 5), and finally to basal ganglia and middle frontal cortex (stage 6). This updated staging scheme is superior to our previous staging scheme, classifying 100 % of the cases (versus 94% in the old scheme), based on criteria provided, and better accounts for Alzheimer’s disease clinical and imaging features, such as Mini-Mental Status Examination score and hippocampal volume. We discuss the relevance of the updated staging scheme, as well as its impact on the prion-like hypothesis of protein spread in neurodegenerative disease. We also address the issue of whether frontotemporal lobar degeneration with TDP-43 could be the primary pathology in stage 6.