Recruitment and Retention for Alzheimer's Disease Diversity Genetic Cohorts in the ADSP (READD-ADSP): A global effort to identify genetic factors in Alzheimer's disease.

Introduction: Alzheimer's disease (AD) remains a major neurocognitive disorder of global health significance. Globalizing ancestral diversity in AD genetics is essential to identify causal variants, improve diagnosis, and enable equitable therapeutic interventions across populations. The Recruitment and Retention for Alzheimer's Disease Diversity Genetic Cohorts in the ADSP (READD-ADSP) initiative addresses this by including African ancestry and Hispanic/Latinx (HL) ancestry populations.

ABCA7 deletion lowers age at onset of Alzheimer's disease and interacts with APOE ε4 synergistically in African-ancestry populations.

Introduction: Apolipoprotein E (APOE) and ABCA7 genes are among the strongest heritable risk factors for Alzheimer's disease (AD) in African-ancestry (AA) populations. APOE 𝜀4 affects both risk and age at onset (AAO), with lower risk in AA populations. This study evaluates the independent and interactive effects of the AA-specific ABCA7 frameshift deletion and APOE 𝜀4 allele on AAO.

Developing biobanking processes for Alzheimer's disease and related dementia research in Africa: Experience from the Recruitment and Retention for Alzheimer's Disease Diversity in the Alzheimer's Disease Sequencing Project (READD-ADSP).

The Recruitment and Retention for Alzheimer's Disease Diversity in the Alzheimer's Disease Sequencing Project (READD-ADSP) aims to recruit 5000 African participants (Alzheimer's disease [AD] and cognitively unimpaired controls) to generate genomic and biomarker data to better characterize AD neurobiology in Africa from countries that constitute the African Dementia Consortium (AfDC). Blood samples from study participants are separated into fractions and transported to the African Coordinating Centre (ACC: Ibadan, Nigeria), where DNA extraction and long-term biospecimen storage are carried out. Plasma and DNA aliquots are shipped to the John P.

Exploring the stability of Alzheimer's disease plasma biomarkers stored for extended periods at -20°C: Implications for resource-constrained environments.

Plasma samples for Alzheimer's disease biomarker analysis are ideally stored at -80°C, which is challenging in low research resource settings. We assessed the stability of pTau181, Aβ, Aβ, NfL, and GFAP in plasma stored at -20°C for 2, 4, 6, and 15 weeks using single molecule array assays. No significant variation was observed in pTau181 and Aβ/Aβ ratio across all timepoints.

Multi-ancestry genome-wide meta-analysis of 56,241 individuals identifies known and novel cross-population and ancestry-specific associations as novel risk loci for Alzheimer's disease.

Background: Limited ancestral diversity has impaired our ability to detect risk variants more prevalent in ancestry groups of predominantly non-European ancestral background in genome-wide association studies (GWAS). We construct and analyze a multi-ancestry GWAS dataset in the Alzheimer's Disease Genetics Consortium (ADGC) to test for novel shared and population-specific late-onset Alzheimer's disease (LOAD) susceptibility loci and evaluate underlying genetic architecture in 37,382 non-Hispanic White (NHW), 6728 African American, 8899 Hispanic (HIS), and 3232 East Asian individuals, performing within ancestry fixed-effects meta-analysis followed by a cross-ancestry random-effects meta-analysis.

Results: We identify 13 loci with cross-population associations including known loci at/near CR1, BIN1, TREM2, CD2AP, PTK2B, CLU, SHARPIN, MS4A6A, PICALM, ABCA7, APOE, and two novel loci not previously reported at 11p12 (LRRC4C) and 12q24.

Alzheimer's disease plasma biomarkers in the Midwestern Amish.

Introduction: Alzheimer's disease (AD) plasma biomarkers are non-invasive measures of the key amyloid beta (Aβ) and tau pathologies. Validation and generalization studies are needed to fully understand their potential for AD prediction and diagnosis in the elderly population.

Methods: In 1067 Amish individuals aged ≥ 65, we measured plasma Aβ and tau to assess their relationships with AD-related outcomes.

Heritability of Alzheimer-related plasma biomarkers in the Amish population.

Introduction: Plasma biomarkers for Alzheimer disease (AD) hold promise for disease diagnosis and prediction, yet their genetic underpinnings remain underexplored.

Methods: We measured plasma amyloid beta 40 (Aβ40), Aβ42, Aβ42/Aβ40, total tau (t-tau), phosphorylated tau 181 (p-tau181), Aβ42/t-tau, Aβ42/p-tau181, neurofilament light chain, and glial fibrillary acidic protein in the Midwestern Amish. Pedigree-based heritability was estimated from multigenerational pedigrees, and SNP-based heritability was derived from single nucleotide polymorphisms (SNPs).

Generalizability of tau and amyloid plasma biomarkers in Alzheimer's disease cohorts of diverse genetic ancestries.

Introduction: Plasma phosphorylated threonine 181 of tau (pTau181) and amyloid beta (Aβ) are biomarkers for differential diagnosis and preclinical detection of Alzheimer disease (AD). Given differences in AD risk across diverse populations, the generalizability of existing biomarker data is not assured.

Methods: In 2086 individuals of diverse genetic ancestries (African American, Caribbean Hispanic, and Peruvian), we measured plasma pTau181 and Aβ42/Aβ40.

Comparing Alzheimer's genes in African, European, and Amerindian induced pluripotent stem cell-derived microglia.

Introduction: Genome-wide association studies (GWAS) studies in Alzheimer's disease (AD) demonstrate ancestry-specific loci. Previous studies in the regulatory architecture have only been conducted in Europeans (EUs), thus studies in additional ancestries are needed. Given the prevalence of AD genes expressed in microglia, we initiated our studies in induced pluripotent stem cell (iPSC) -derived microglia.

Alzheimer Disease Plasma Biomarkers in the Mid-Western Amish.

Introduction: Alzheimer disease (AD) plasma biomarkers are noninvasive measures of the key amyloid beta (Aβ) and tau pathologies. Validation and generalization studies are needed to fully understand their potential for AD prediction and diagnosis in the elderly population.

Methods: In 1,067 Amish individuals aged ≥ 65, we measured plasma Aβ and tau to assess their relationships with AD-related outcomes.

Ancestral Genomic Functional Differences in Oligodendroglia: Implications for Alzheimer's Disease.

Background: This study aims to elucidate ancestry-specific changes to the genomic regulatory architecture in induced pluripotent stem cell (iPSC)-derived oligodendroglia, focusing on their implications for Alzheimer's disease (AD). This work addresses the lack of diversity in previous iPSC studies by including ancestries that contribute to African American (European/African) and Hispanic/Latino populations (Amerindian/African/European).

Methods: We generated 12 iPSC lines-four African, four Amerindian, and four European- from both AD patients and non-cognitively impaired individuals, with varying genotypes ( and ).

AD plasma biomarkers are stable for an extended period at -20°C: implications for resource-constrained environments.

Standard procedures for measuring Alzheimer's disease (AD) plasma biomarkers include storage at -80°C. This is challenging in countries lacking research infrastructure, such -80°C freezer. To investigate stability of AD biomarkers from plasma stored at -20°C, we compared aliquots stored at -80°C and others at -20°C for two, four, six, fifteen, and thirty-five weeks.

Generalizability of Tau and Amyloid Plasma Biomarkers in Alzheimer's Disease Cohorts of Diverse Genetic Ancestries.

Introduction: Plasma phosphorylated threonine-181 of Tau and amyloid beta are biomarkers for differential diagnosis and preclinical detection of Alzheimer disease (AD). Given differences in AD risk across diverse populations, generalizability of existing biomarker data is not assured.

Methods: In 2,086 individuals of diverse genetic ancestries (African American, Caribbean Hispanic, and Peruvians) we measured plasma pTau-181 and Aβ42/Aβ40.

Genetic analyses in multiplex families confirms chromosome 5q35 as a risk locus for Alzheimer's Disease in individuals of African Ancestry.

There is a paucity of genetic studies of Alzheimer Disease (AD) in individuals of African Ancestry, despite evidence suggesting increased risk of AD in the African American (AA) population. We performed whole-genome sequencing (WGS) and multipoint linkage analyses in 51 multi-generational AA AD families ascertained through the Research in African American Alzheimer Disease Initiative (REAAADI) and the National Institute on Aging Late Onset Alzheimer's disease (NIA-LOAD) Family Based Study. Variants were prioritized on minor allele frequency (<0.

An Alzheimer's disease risk variant in TTC3 modifies the actin cytoskeleton organization and the PI3K-Akt signaling pathway in iPSC-derived forebrain neurons.

A missense variant in the tetratricopeptide repeat domain 3 (TTC3) gene (rs377155188, p.S1038C, NM_003316.4:c 0.

An Alzheimer's disease risk variant in modifies the actin cytoskeleton organization and the PI3K-Akt signaling pathway in iPSC-derived forebrain neurons.

Unlabelled: A missense variant in the ( ) gene (rs377155188, p.S1038C, NM_003316.4:c.

Admixture mapping identifies novel Alzheimer's disease risk regions in African Americans.

Background: This study used admixture mapping to prioritize the genetic regions associated with Alzheimer's disease (AD) in African American (AA) individuals, followed by ancestry-aware regression analysis to fine-map the prioritized regions.

Methods: We analyzed 10,271 individuals from 17 different AA datasets. We performed admixture mapping and meta-analyzed the results.

Genetic variants in the SHISA6 gene are associated with delayed cognitive impairment in two family datasets.

Introduction: Studies of cognitive impairment (CI) in Amish communities have identified sibships containing CI and cognitively unimpaired (CU) individuals. We hypothesize that CU individuals may carry protective alleles delaying age at onset (AAO) of CI.

Methods: A total of 1522 individuals screened for CI were genotyped.

Genetic architecture of RNA editing regulation in Alzheimer's disease across diverse ancestral populations.

Most Alzheimer's disease (AD)-associated genetic variants do not change protein coding sequence and thus likely exert their effects through regulatory mechanisms. RNA editing, the post-transcriptional modification of RNA bases, is a regulatory feature that is altered in AD patients that differs across ancestral backgrounds. Editing QTLs (edQTLs) are DNA variants that influence the level of RNA editing at a specific site.

Linkage of Alzheimer disease families with Puerto Rican ancestry identifies a chromosome 9 locus.

The genetic admixture of Caribbean Hispanics provides an opportunity to discover novel genetic factors in Alzheimer disease (AD). We sought to identify genetic variants for AD through a family-based design using the Puerto Rican (PR) Alzheimer Disease Initiative (PRADI). Whole-genome sequencing (WGS) and parametric linkage analysis were performed for 100 individuals from 23 multiplex PRADI families.

Dissecting the role of Amerindian genetic ancestry and the ApoE ε4 allele on Alzheimer disease in an admixed Peruvian population.

Alzheimer disease (AD) is the leading cause of dementia in the elderly and occurs in all ethnic and racial groups. The apolipoprotein E (ApoE) ε4 is the most significant genetic risk factor for late-onset AD and shows the strongest effect among East Asian populations followed by non-Hispanic white populations and has a relatively lower effect in African descent populations. Admixture analysis in the African American and Puerto Rican populations showed that the variation in ε4 risk is correlated with the genetic ancestral background local to the ApoE gene.

Increased APOE ε4 expression is associated with the difference in Alzheimer's disease risk from diverse ancestral backgrounds.

Introduction: Apolipoprotein E (APOE) ε4 confers less risk for Alzheimer's disease (AD) in carriers with African local genomic ancestry (ALA) than APOE ε4 carriers with European local ancestry (ELA). Cell type specific transcriptional variation between the two local ancestries (LAs) could contribute to this disease risk differences.

Methods: Single-nucleus RNA sequencing was performed on frozen frontal cortex of homozygous APOE ε4/ε4 AD patients: seven with ELA, four with ALA.