A study on factors associated with age of Alzheimer's disease onset / 中华流行病学杂志

Objective: To understand the distribution characteristics of age of Alzheimer's disease (AD) onset and influencing factors. Methods: Based on the follow-up data of Alzheimer's Disease Neuroimaging Initiative from 2005 to 2022, participants with normal cognition (CN) or mild cognitive impairment (MCI) at baseline survey, and those with progression to AD during follow-up period were selected as study subjects. Univariate analysis and multiple linear regression analysis were performed to explore the associations of gender, race, number of ApoE ε4 genes carried, family history, years of education and marital status with the age of AD onset. Results: A total of 405 participants, with an average age of (74.0±6.9) years at baseline survey, progressed to AD during follow up period. The age of AD onset was (76.6±7.5) years, and age of onset in men was about 1.9 years later than women. Multiple linear regression analysis showed that for each increase in ApoE ε4 gene number, the age of AD onset was about 0.344 years earlier. The age of AD onset was 4.007 years earlier for those with MCI at baseline survey compared with those with CN. Years of education were not significantly associated with the age of onset of AD (P>0.05). Conclusion: Those who carry ApoE ε4 gene, and have MCI at baseline survey might have earlier age of AD onset.

Human 8-cell embryos enable efficient induction of disease-preventive mutations without off-target effect by cytosine base editor

Approximately 140 million people worldwide are homozygous carriers of APOE4 (ε4), a strong genetic risk factor for late onset familial and sporadic Alzheimer's disease (AD), 91% of whom will develop AD at earlier age than heterozygous carriers and noncarriers. Susceptibility to AD could be reduced by targeted editing of APOE4, but a technical basis for controlling the off-target effects of base editors is necessary to develop low-risk personalized gene therapies. Here, we first screened eight cytosine base editor variants at four injection stages (from 1- to 8-cell stage), and found that FNLS-YE1 variant in 8-cell embryos achieved the comparable base conversion rate (up to 100%) with the lowest bystander effects. In particular, 80% of AD-susceptible ε4 allele copies were converted to the AD-neutral ε3 allele in human ε4-carrying embryos. Stringent control measures combined with targeted deep sequencing, whole genome sequencing, and RNA sequencing showed no DNA or RNA off-target events in FNLS-YE1-treated human embryos or their derived stem cells. Furthermore, base editing with FNLS-YE1 showed no effects on embryo development to the blastocyst stage. Finally, we also demonstrated FNLS-YE1 could introduce known protective variants in human embryos to potentially reduce human susceptivity to systemic lupus erythematosus and familial hypercholesterolemia. Our study therefore suggests that base editing with FNLS-YE1 can efficiently and safely introduce known preventive variants in 8-cell human embryos, a potential approach for reducing human susceptibility to AD or other genetic diseases.

Factors Influencing Alzheimer's Disease Risk: Whether and How They are Related to the APOE Genotype / 神经科学通报·英文版

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease featuring progressive cognitive impairment. Although the etiology of late-onset AD remains unclear, the close association of AD with apolipoprotein E (APOE), a gene that mainly regulates lipid metabolism, has been firmly established and may shed light on the exploration of AD pathogenesis and therapy. However, various confounding factors interfere with the APOE-related AD risk, raising questions about our comprehension of the clinical findings concerning APOE. In this review, we summarize the most debated factors interacting with the APOE genotype and AD pathogenesis, depict the extent to which these factors relate to APOE-dependent AD risk, and discuss the possible underlying mechanisms.

Apolipoprotein E polymorphism and functional disability in Brazilian elders: the Bambuí Health and Aging Study / Polimorfismo da apolipoproteína E e incapacidade funcional em idosos brasileiros: Projeto Bambuí / Polimorfismo de la apolipoproteína E e incapacidad funcional en los ancianos brasileños: Proyecto Bambuí

Abstract Numerous studies have associated the apolipoprotein E (apoE) ε4 allele with worse health status, but few have assessed the existence of genotype-dependent variations in functional performance. Among participants in the Bambuí Health and Aging Study, Minas Gerais State, Brazil, 1,408 elderly underwent apoE genotyping. Functionality was assessed with a questionnaire, and individuals were classified as dependent in basic activities of daily living (BADLs), instrumental activities of daily living (IADLs), and mobility. The association between apoE genotype and functional status was assessed by logistic regression, taking confounding factors into account. Presence of ε4 allele was associated with lower odds of mobility deficit (OR = 0.65; 95%CI: 0.47-0.92) in the adjusted analysis. There were no significant differences in relation to presence of dependency in BADLs and IADLs. The reasons are not entirely understood, but they may involve the role of ε4 allele as a "thrifty gene" in a sample exposed to high risk of infectious and nutritional diseases in the past.

Resumo Inúmeros estudos têm associado o alelo ε4 da apolipoproteína E (apoE) com pior condição de saúde, mas poucos avaliaram a existência de variações genótipo-dependentes no desempenho funcional. Entre os participantes da coorte de Bambuí, Minas Gerais, Brasil, 1.408 idosos foram submetidos à genotipagem da apoE. A funcionalidade foi avaliada por questionário, sendo os indivíduos classificados em dependentes para atividades básicas da vida diária (ABVDs), atividades instrumentais da vida diária (AIVDs) e mobilidade. A associação entre o genótipo da apoE e o estado funcional foi avaliada pela regressão logística, considerando variáveis de confusão. A presença do alelo ε4 foi associada a uma menor chance de déficit na mobilidade (OR = 0,65; IC95%: 0,47-0,92), na análise ajustada. Não houve diferenças significativas em relação à presença de incapacidades em ABVDs e AIVDs. Os motivos não estão completamente compreendidos, mas podem envolver o seu papel como um "thrifty gene" em uma amostra exposta a um risco elevado de doenças infecciosas e nutricionais no passado.

Resumen Innumerables estudios han asociado el alelo ε4 de la apolipoproteína E (apoE) con una peor condición de salud, pero pocos evaluaron la existencia de variaciones genotipo-dependientes en el desempeño funcional. Entre los participantes de la cohorte de Bambuí, Minas Gerais, Brasil, 1.408 ancianos fueron sometidos a una determinación del genotipo de la apoE. La funcionalidad fue evaluada por cuestionario, siendo los individuos clasificados en: dependientes para actividades básicas de la vida diaria (ABVDs), actividades instrumentales de la vida diaria (AIVDs) y movilidad. La asociación entre el genotipo de la apoE y el estado funcional fue evaluada por regresión logística, considerando variables de confusión. La presencia del alelo ε4 fue asociada a una menor probabilidad de déficit en la movilidad (OR = 0,65; IC95%: 0,47-0,92) en el análisis ajustado. No hubo diferencias significativas en relación con la presencia de incapacidades en ABVDs y AIVDs. Los motivos no están completamente claros, pero pueden están involucrados por su papel como un "thrifty gene" en una muestra expuesta a un riesgo elevado de enfermedades infecciosas y nutricionales en el pasado.

Independent and Interactive Influences of the APOE Genotype and Beta-Amyloid Burden on Cognitive Function in Mild Cognitive Impairment

This study aimed to investigate the independent and interactive influences of apolipoprotein E (APOE) epsilon4 and beta-amyloid (Abeta) on multiple cognitive domains in a large group of cognitively normal (CN) individuals and patients with mild cognitive impairment (MCI) and Alzheimer's disease (AD). Participants were included if clinical and cognitive assessments, amyloid imaging, and APOE genotype were all available from the Alzheimer's Disease Neuroimaging Initiative database (CN = 324, MCI = 502, AD = 182). Individuals with one or two copies of epsilon4 were designated as APOE epsilon4 carriers (epsilon4+); individuals with no epsilon4 were designated as APOE epsilon4 non-carriers (epsilon4-). Based on mean florbetapir standard uptake value ratios, participants were classified as Abeta burden-positive (Abeta+) or Abeta burden-negative (Abeta-). In MCI, APOE epsilon4 effects were predominantly observed on frontal executive function, with epsilon4+ participants exhibiting poorer performances; Abeta positivity had no influence on this effect. Abeta effects were observed on global cognition, memory, and visuospatial ability, with Abeta+ participants exhibiting poorer performances. Measures of frontal executive function were not influenced by Abeta. Interactive effects of APOE epsilon4+ and Abeta were observed on global cognition and verbal recognition memory. Abeta, not APOE epsilon4+, influenced clinical severity and functional status. The influences of APOE epsilon4+ and Abeta on cognitive function were minimal in CN and AD. In conclusion, we provide further evidence of both independent and interactive influences of APOE epsilon4+ and Abeta on cognitive function in MCI, with APOE epsilon4+ and Abeta showing dissociable effects on executive and non-executive functions, respectively.