scholarly journals Similar Genetic Architecture of Alzheimer’s Disease and Differential APOE Effect Between Sexes

2021 ◽  
Vol 13 ◽  
Author(s):  
Hao Wang ◽  
Min-Tzu Lo ◽  
Sara Brin Rosenthal ◽  
Carolina Makowski ◽  
Ole A. Andreassen ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Sex Differences ◽  
Genetic Correlation ◽  
Genetic Architecture ◽  
Clinical Manifestations ◽  
Genome Wide ◽  
Significant Locus ◽  
Active Research ◽  
Or Gene

Sex differences have been observed in the clinical manifestations of Alzheimer’s disease (AD) and elucidating their genetic basis is an active research topic. Based on autosomal genotype data of 7,216 men and 10,680 women, including 8,136 AD cases and 9,760 controls, we explored sex-related genetic heterogeneity in AD by investigating SNP heritability, genetic correlation, as well as SNP- and gene-based genome-wide analyses. We found similar SNP heritability (men: 19.5%; women: 21.5%) and high genetic correlation (Rg = 0.96) between the sexes. The heritability of APOE ε4-related risks for AD, after accounting for effects of all SNPs excluding chromosome 19, was nominally, but not significantly, higher in women (10.6%) than men (9.7%). In age-stratified analyses, ε3/ε4 was associated with a higher risk of AD among women than men aged 65–75 years, but not in the full sample. Apart from APOE, no new significant locus was identified in sex-stratified gene-based analyses. Our result of the high genetic correlation indicates overall similar genetic architecture of AD in both sexes at the genome-wide averaged level. Our study suggests that clinically observed sex differences may arise from sex-specific variants with small effects or more complicated mechanisms involving epigenetic alterations, sex chromosomes, or gene-environment interactions.

scholarly journals Sex-dependent polygenic effects on the clinical progressions of Alzheimer’s disease

2019 ◽  
Author(s):  
Chun Chieh Fan ◽  
Sarah J. Banks ◽  
Wesley K. Thompson ◽  
Chi-Hua Chen ◽  
Linda K. McEvoy ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Sex Differences ◽  
Hazard Function ◽  
Genetic Architecture ◽  
Predictive Power ◽  
Disease Onset ◽  
Risk Scores ◽  
Genome Wide ◽  
Crossover Analysis

AbstractSex differences in the manifestations of Alzheimer’s disease (AD) are under intense investigations 1,2. Despite the emerging importance of polygenic predictions for AD 3–8, the sex-dependent polygenic effects have not been demonstrated. Here, using a sex crossover analysis, we show that sex-dependent autosomal genetic effects on AD 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. Sex-matched polygenic hazard scores (PHS) have significantly stronger associations with age-at-disease-onset, clinical progressions, amyloid depositions, neurofibrillary tangles, and composite neuropathological scores, than sex-mismatched PHS, independent of apolipoprotein E. Models without using hazard weights, i.e. polygenic risk scores (PRS), have lower predictive power than PHS and show no evidence for sex differences. Our results indicate revealing sex-dependent genetic architecture requires the consideration of temporal processes of AD. This has strong implications not only for the genetic underpinning of AD but also for how we estimate sex-dependent polygenic effects for clinical use.

scholarly journals Neuropathological correlates and genetic architecture of microglial activation in elderly human brain

2018 ◽  
Author(s):  
Daniel Felsky ◽  
Tina Roostaei ◽  
Kwangsik Nho ◽  
Shannon L. Risacher ◽  
Elizabeth M. Bradshaw ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Human Brain ◽  
Cognitive Decline ◽  
Genetic Architecture ◽  
Microglial Activation ◽  
Brain Health ◽  
Positron Emission ◽  
Genome Wide

AbstractMicroglia, the resident immune cells of the brain, have important roles in brain health. However, little is known about the regulation and consequences of microglial activation in the aging human brain. We assessed the effect of microglial activation in the aging human brain by calculating the proportion of activated microglia (PAM), based on morphologically defined stages of activation in four regions sampled postmortem from up to 225 elderly individuals. We found that cortical and not subcortical PAM measures were strongly associated with β-amyloid, tau-related neuropathology, and rates of cognitive decline. Effect sizes for PAM measures are substantial, comparable to that of APOE ɛ4, the strongest genetic risk factor for Alzheimer’s disease. Mediation modeling suggests that PAM accelerates accumulation of tau pathology leading to cognitive decline, supporting an upstream role for microglial activation in Alzheimer’s disease. Genome-wide analyses identified a common variant (rs2997325) influencing cortical PAM that also affected in vivo microglial activation measured by positron emission tomography using [11C]-PBR28 in an independent cohort. Finally, we identify overlaps of PAM’s genetic architecture with those of Alzheimer’s disease, educational attainment, and several other traits.

scholarly journals Hearing difficulty is linked to Alzheimer’s disease by common genetic vulnerability, not shared genetic architecture

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Fatin N. Zainul Abidin ◽  
Helena R. R. Wells ◽  
Andre Altmann ◽  
Sally J. Dawson
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Genetic Correlation ◽  
Genetic Architecture ◽  
Association Studies ◽  
Genome Wide Association Studies ◽  
Genetic Associations ◽  
Age Related ◽  
Hearing Difficulty ◽  
Shared Genetic

AbstractAge-related hearing loss was recently established as the largest modifiable risk factor for Alzheimer’s disease (AD), however, the reasons for this link remain unclear. We investigate shared underlying genetic associations using results from recent large genome-wide association studies (GWAS) on adult hearing difficulty and AD. Genetic correlation and Mendelian randomization (MR) analysis do not support a genetic correlation between the disorders, but suggest a direct causal link from AD genetic risk to hearing difficulty, driven by APOE. Systematic MR analyses on the effect of other traits revealed shared effects of glutamine, gamma-glutamylglutamine, and citrate levels on reduced risk of both hearing difficulty and AD. In addition, pathway analysis on GWAS risk variants suggests shared function in neuronal signalling pathways as well as etiology of diabetes and cardiovascular disease. However, after multiple testing corrections, neither analysis led to statistically significant associations. Altogether, our genetic-driven analysis suggests hearing difficulty and AD are linked by a shared vulnerability in molecular pathways rather than by a shared genetic architecture.

scholarly journals Sex differences in the genetic predictors of Alzheimer’s pathology

Brain ◽  
2019 ◽  
Vol 142 (9) ◽  
pp. 2581-2589 ◽  
Author(s):  
Logan Dumitrescu ◽  
Lisa L Barnes ◽  
Madhav Thambisetty ◽  
Gary Beecham ◽  
Brian Kunkle ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Sex Differences ◽  
Disease Risk ◽  
Association Studies ◽  
Age At Onset ◽  
Genome Wide Association Studies ◽  
Genetic Associations ◽  
Data Repositories ◽  
Genome Wide

Abstract Autopsy measures of Alzheimer’s disease neuropathology have been leveraged as endophenotypes in previous genome-wide association studies (GWAS). However, despite evidence of sex differences in Alzheimer’s disease risk, sex-stratified models have not been incorporated into previous GWAS analyses. We looked for sex-specific genetic associations with Alzheimer’s disease endophenotypes from six brain bank data repositories. The pooled dataset included 2701 males and 3275 females, the majority of whom were diagnosed with Alzheimer’s disease at autopsy (70%). Sex-stratified GWAS were performed within each dataset and then meta-analysed. Loci that reached genome-wide significance (P < 5 × 10−8) in stratified models were further assessed for sex interactions. Additional analyses were performed in independent datasets leveraging cognitive, neuroimaging and CSF endophenotypes, along with age-at-onset data. Outside of the APOE region, one locus on chromosome 7 (rs34331204) showed a sex-specific association with neurofibrillary tangles among males (P = 2.5 × 10−8) but not females (P = 0.85, sex-interaction P = 2.9 × 10−4). In follow-up analyses, rs34331204 was also associated with hippocampal volume, executive function, and age-at-onset only among males. These results implicate a novel locus that confers male-specific protection from tau pathology and highlight the value of assessing genetic associations in a sex-specific manner.

scholarly journals The Histone H3 K4me3, K27me3, and K27ac Genome-Wide Distributions Are Differently Influenced by Sex in Brain Cortexes and Gastrocnemius of the Alzheimer’s Disease PSAPP Mouse Model

Epigenomes ◽  
2021 ◽  
Vol 5 (4) ◽  
pp. 26
Author(s):  
Francesca Casciaro ◽  
Giuseppe Persico ◽  
Martina Rusin ◽  
Stefano Amatori ◽  
Claire Montgomery ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Sex Differences ◽  
Mouse Model ◽  
Histone H3 ◽  
Signal Distribution ◽  
Dementia Prevalence ◽  
Genome Wide ◽  
Gastrocnemius Muscles ◽  
Behavioral Mechanisms

Background: Women represent the majority of Alzheimer’s disease patients and show typical symptoms. Genetic, hormonal, and behavioral mechanisms have been proposed to explain sex differences in dementia prevalence. However, whether sex differences exist in the epigenetic landscape of neuronal tissue during the progression of the disease is still unknown. Methods: To investigate the differences of histone H3 modifications involved in transcription, we determined the genome-wide profiles of H3K4me3, H3K27ac, and H3K27me3 in brain cortexes of an Alzheimer mouse model (PSAPP). Gastrocnemius muscles were also tested since they are known to be different in the two sexes and are affected during the disease progression. Results: Correlation analysis distinguished the samples based on sex for H3K4me3 and H3K27me3 but not for H3K27ac. The analysis of transcription starting sites (TSS) signal distribution, and analysis of bounding sites revealed that gastrocnemius is more influenced than brain by sex for the three histone modifications considered, exception made for H3K27me3 distribution on the X chromosome which showed sex-related differences in promoters belonging to behavior and cellular or neuronal spheres in mice cortexes. Conclusions: H3K4me3, H3K27ac, and H3K27me3 signals are slightly affected by sex in brain, with the exception of H3K27me3, while a higher number of differences can be found in gastrocnemius.

scholarly journals Sex-dependent autosomal effects on clinical progression of Alzheimer’s disease

Brain ◽  
2020 ◽  
Vol 143 (7) ◽  
pp. 2272-2280 ◽  
Author(s):  
Chun Chieh Fan ◽  
Sarah J Banks ◽  
Wesley K Thompson ◽  
Chi-Hua Chen ◽  
Linda K McEvoy ◽  
...  
Keyword(s):  
Alzheimer’S Disease ◽  
Alzheimer's Disease ◽  
Sex Differences ◽  
Hazard Function ◽  
Predictive Power ◽  
Disease Onset ◽  
Risk Scores ◽  
Clinical Progression ◽  
Genome Wide ◽  
Crossover Analysis

Abstract 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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