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BACKGROUND: Few rare variants have been identified in genetic loci from genome‐wide association studies (GWAS) of Alzheimer's disease (AD), limiting understanding of mechanisms, risk assessment, and genetic counseling. METHODS: Using genome sequencing data from 197 families in the National Institute on Aging Alzheimer's Disease Family Based Study and 214 Caribbean Hispanic families, we searched for rare coding variants within known GWAS loci from the largest published study. RESULTS: Eighty‐six rare missense or loss‐of‐function (LoF) variants completely segregated in 17.5% of families, but in 91 (22.1%) families Apolipoprotein E (APOE)‐휀4 was the only variant segregating. However, in 60.3% of families, APOE 휀4, missense, and LoF variants were not found within the GWAS loci. DISCUSSION: Although APOE 휀4and several rare variants were found to segregate in both family datasets, many families had no variant accounting for their disease. This suggests that familial AD may be the result of unidentified rare variants. Highlights: Rare coding variants from GWAS loci segregate in familial Alzheimer's disease.Missense or loss of function variants were found segregating in nearly 7% of families.APOE‐휀4 was the only segregating variant in 29.7% in familial Alzheimer's disease.In Hispanic and non‐Hispanic families, different variants were found in segregating genes.No coding variants were found segregating in many Hispanic and non‐Hispanic families. [ABSTRACT FROM AUTHOR]

Hippocampal subfield atrophy is a prime structural change in the brain, associated with cognitive aging and neurodegenerative diseases such as Alzheimer's disease. Recent developments in genome-wide association studies (GWAS) have identified genetic loci that characterize the risk of hippocampal volume loss based on the processes of normal and abnormal aging. Polygenic risk scores are the genetic proxies mimicking the genetic role of the pre-existing vulnerabilities of the underlying mechanisms influencing these changes. Discriminating the genetic predispositions of hippocampal subfield atrophy between cognitive aging and neurodegenerative diseases will be helpful in understanding the disease etiology. In this study, we evaluated the polygenic risk of Alzheimer's disease (AD PGRS) for hippocampal subfield atrophy in 1,086 individuals (319 cognitively normal (CN), 591 mild cognitively impaired (MCI), and 176 Alzheimer's disease dementia (ADD)). Our results showed a stronger association of AD PGRS effect on the left hemisphere than on the right hemisphere for all the hippocampal subfield volumes in a mixed clinical population (CN+MCI+ADD). The subfields CA1, CA4, hippocampal tail, subiculum, presubiculum, molecular layer, GC-ML-DG, and HATA showed stronger AD PGRS associations with the MCI+ADD group than with the CN group. The subfields CA3, parasubiculum, and fimbria showed moderately higher AD PGRS associations with the MCI+ADD group than with the CN group. Our findings suggest that the eight subfield regions, which were strongly associated with AD PGRS are likely involved in the early stage ADD and a specific focus on the left hemisphere could enhance the early prediction of ADD. [ABSTRACT FROM AUTHOR]

Background: Amyloid‐β plaques and tau neurofibrillary tangles are the pathological hallmarks of Alzheimer's disease (AD). Previously, genetic studies on amyloid‐β mediated AD pathogenesis dominated the field, and genetic studies on tau pathology are limited by comparison. Prior studies suggest that the spread of tau neurofibrillary tangles within the medial temporal lobe occurs following abnormal deposition of amyloid‐β, leading to cognitive impairment. Although amyloid‐β and tau both play a role in AD pathogenesis, exact genetic pathways associated with them are still unknown. Method: We performed genome‐wide association study (GWAS) with brain Tau standard uptake value ratios (SUVRs) measured from positron emission tomography (PET) images from the A4 ((N = 311 with preclinical AD;female = 62%;tau mean‐SUVR = 1.076±0.06) and ADNI studies (N = 375‐280 cognitively normal, 76 mild cognitively impaired and 19 AD;female = 53%;tau mean‐SUVR = 1.12±0.13). Models were adjusted for age, sex and APOE‐ε4 dosage. Additionally, we evaluated the association of amyloid‐β and tau SUVRs with AD polygenic risk scores (PRS). PRS was calculated using genome‐wide variants, excluding 1MB region flanking APOE, and effect sizes from Kunkle et al GWAS study of clinical AD. Result: Analysis of tau‐SUVR in 686 participants, identified five genome‐wide significant loci: rs78636169 (P = 1.37×10−9) in JARID2, rs114272033 (P = 7.87×10−9) in ISCA1P2, rs7292124 (P = 1.73×10−8) in RP1‐272J12.1, rs114742337 (P = 2.85×10−8) in RP4‐771M4.2, and rs138338441 (P = 3.91×10−8) in AC092684.1. Rs13412014 in AC007364.1 and rs9393067 in RP11‐314C16.1 were also associated with amyloid‐SUVR in a previous large GWAS. Two loci previously associated with clinical AD in a recent large GWA study, INPP5D (rs10933431) and SEC61G (rs76928645), were also nominally associated (P<0.05) with tau deposition in our study. Genes associated with Tau‐SUVR are enriched in the Schaffer axonal collaterals (P<1×10−05) that form synapses in hippocampus. Genome‐wide PRS of AD (excluding APOE region) was strongly associated with amyloid‐SUVR (P = 3.21×10−11;R2 = 0.077) but only weakly associated with tau‐SUVR (P = 1.38×10−04;R2 = 0.027). We are in the process of replicating our results in an independent cohort of 700 participants with measurements of tau deposition. Conclusion: We identified five novel genetic loci associated with tau pathology. Several genes involved in tau deposition were also associated with amyloid load in the brain. Taken together, our findings will clarify the genetic pathways that effect both amyloid and tau pathology in AD. [ABSTRACT FROM AUTHOR]

Variants in the APOE gene region may explain ethnic differences in the association of Alzheimer's disease (AD) with ε4. Ethnic differences in allele frequencies for three APOE 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 APOE promoter SNP rs405509 T alleles in EastAs (TT: OR (odds ratio) = 27.02, p = 8.80 × 10−94; GT: OR = 15.87, p = 2.62 × 10−9) and EuroAs (TT: OR = 18.13, p = 2.69 × 10−108; GT: OR = 12.63, p = 3.44 × 10−64), and rs405509-T homozygotes had a younger onset and more severe cortical atrophy than those with G-allele. Functional experiments using APOE promoter fragments demonstrated that TT lowered APOE 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 APOE expression might lower AD risk among ε4 homozygotes. [ABSTRACT FROM AUTHOR]

Background: Few rare variants have been identified in genetic loci from genome-wide association studies (GWAS) of Alzheimer's disease (AD), limiting understanding of mechanisms, risk assessment, and genetic counseling., Methods: Using genome sequencing data from 197 families in the National Institute on Aging Alzheimer's Disease Family Based Study and 214 Caribbean Hispanic families, we searched for rare coding variants within known GWAS loci from the largest published study., Results: Eighty-six rare missense or loss-of-function (LoF) variants completely segregated in 17.5% of families, but in 91 (22.1%) families Apolipoprotein E (APOE)-𝜀4 was the only variant segregating. However, in 60.3% of families, APOE 𝜀4, missense, and LoF variants were not found within the GWAS loci., Discussion: Although APOE 𝜀4and several rare variants were found to segregate in both family datasets, many families had no variant accounting for their disease. This suggests that familial AD may be the result of unidentified rare variants., Highlights: Rare coding variants from GWAS loci segregate in familial Alzheimer's disease. Missense or loss of function variants were found segregating in nearly 7% of families. APOE-𝜀4 was the only segregating variant in 29.7% in familial Alzheimer's disease. In Hispanic and non-Hispanic families, different variants were found in segregating genes. No coding variants were found segregating in many Hispanic and non-Hispanic families., (© 2024 The Author(s). Alzheimer's & Dementia published by Wiley Periodicals LLC on behalf of Alzheimer's Association.)

Background: Genetic research on Alzheimer's disease (AD) has primarily focused on amyloid-β (Aβ) pathogenesis, with fewer studies exploring tau pathology. Elucidating the genetic basis of tau pathology could identify novel pathways in AD., Methods: We conducted a genome-wide association study of tau standard uptake value ratios (SUVRs) from [18] F-flortaucipir positron emission tomography (PET) images to identify genetic variants underlying Tau pathology. Genetic data and tau-SUVRs from [18] F-flortaucipir PET images were acquired from the A4 (311 with preclinical AD) and ADNI (280 cognitively normal, 76 with mild cognitive impairment, and 19 AD patients) studies. Circulating plasma proteins in UK Biobank Pharma Proteomics Project (UKBPPP, N=54,129) were used to validate genetic findings. SNP genotypes were tested for association with Tau-SUVR levels adjusting for age, sex and population substructure variables. AD association of polygenic risk scores (PRS) of tau and amyloid-SUVRs were assessed. Causal effect of plasma protein levels on Tau pathology were tested using Mendelian randomization analyses., Results: GWAS of tau-SUVR revealed two significant loci: rs78636169 ( P =5.76×10 -10 ) in JARID2 and rs7292124 ( P =2.20×10 -8 ) near ISX . Gene-based analysis of tau deposition highlighted APOE ( P =2.55×10 -6 ), CTNNA3 ( P =2.86×10 -6 ) and JARID2 ( P =1.23×10 -4 ), a component of the PRC2 multi-protein complex which regulates gene expression. Mendelian randomization analysis of available circulating plasma proteins in the UK Biobank Pharma Proteomics Project (UKBPPP) identified LRRFIP1, a protein that binds with PRC2 multi-protein complex, as potentially causally linked to tau pathology. Genes associated with both amyloid and tau pathologies were enriched in endocytosis and signal transduction pathways. AD polygenic risk score (PRS) was associated with amyloid-SUVR but not with tau-SUVR. Amyloid-SUVR PRS had a notable association with AD clinical status, particularly in younger APOE -ε4 carriers, whereas tau-SUVR PRS showed a stronger association in older carriers., Conclusion: We identified a novel potential therapeutic target, JARID2 in the PRC2 multi-protein complex, for tau pathology. Furthermore, gene pathway analysis clarified the distinct roles of Aβ and tau in AD progression, underscoring the complexity of genetic influences across different stages of the disease.