Late-onset Alzheimer's disease (LOAD) is a multifactorial neurodegenerative disorder that corresponds to most Alzheimer's disease (AD) cases. Inflammation is frequently related to AD, whereas microglial cells are the major phagocytes in the brain and mediate the removal of Aβ peptides. Microglial cell dsyregulation might contribute to the formation of amyloid plaques, a hallmark of AD. Genome-wide association studies have reported genetic loci associated with the inflammatory pathway involved in AD. Among them, rs3865444 CD33, rs3764650 ABCA7, rs6656401 CR1, and rs610932 MS4A6A variants in microglial genes are associated with LOAD. These variants are proposed to participate in the clearance of Aβ peptides. However, their association with LOAD was not validated in all case-control studies. Thus, the present work aimed to assess the involvement of CD33 (rs3865444), ABCA7 (rs3764650), CR1 (rs6656401), and MS4A6A (rs610932) with LOAD in a sample from southeastern Brazil. The genotype frequencies were assessed in 79 AD patients and 145 healthy elders matched for sex and age. We found that rs3865444 CD33 acts as a protective factor against LOAD. These results support a role for the inflammatory pathway in LOAD.

Alzheimer's disease (AD) is a complex neurodegenerative disorder and the most common type of dementia in the elderly. Although its cause is not completely known, several studies suggest that oxidative stress plays an important role in the etiology of this disease. The SIRT1 and SOD2 proteins are linked to pathways that may impair oxidative stress. In this study, we analyzed the association between polymorphisms in these genes and in the APOE gene, through RT-PCR, as well as between environmental factors and the risk of AD. Additionally, the thiobarbituric acid reactive substance assay was performed to estimate the plasma level of malondialdehyde (MDA), a biomarker of lipid peroxidation. Furthermore, some cytogenetic studies indicate that cells of AD patients show increased chromosomal damage; thus, we performed the micronucleus cytome assay to assess cytogenetic damage in AD patients. As expected, the APOE polymorphisms were found to be highly associated with AD. Additionally, the CT genotype of the SIRT1 gene showed a positive association with the disease. The frequencies of genomic damage (micronucleus, buds, nucleoplasmic bridges and binucleated cells), the presence of cell death biomarkers (condensed chromatin, karyorrhexis and pyknosis), and the plasma level of MDA were significantly greater in AD patients than in controls. Our results support the hypothesis that AD is a condition with increased oxidative stress and genomic instability, which may contribute to the neurodegeneration in AD.

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Background Type 2 diabetes mellitus (T2DM) and obesity are complex pandemic diseases in the 21st century. Worldwide, the T allele rs7903146 in the TCF7L2 gene is recognized as a strong GWAS signal associated with T2DM. However, the association between the C allele and obesity is still poorly explored and needs to be replicated in other populations. Thus, the primary objectives of this study were to evaluate the TCF7L2 rs7903146 association with T2DM according to BMI status and to determine if this variant is related to obesity and BMI variation in a cohort of elderly Brazilians. Methods A total of 1,023 participants from an elderly census-based cohort called SABE (Saúde, Bem Estar e Envelhecimento—Health, Well-Being and Aging) were stratified by BMI status and type 2 diabetes presence. The TCF7L2 genotypes were filtered from the Online Archive of Brazilian Mutations (ABraOM—Online Archive of Brazilian Mutations) database, a web-based public database with sequencing data of samples of the SABE’s participants. Logistic regression models and interaction analyses were performed. The BMI variation (∆BMI) was calculated from anthropometric data collected in up to two time-points with a ten-year-assessment interval. Results The association between the rs7903146 T allele and T2DM was inversely proportional to the BMI status, with an increased risk in the normal weight group (OR 3.36; 95% CI [1.46–7.74]; P = 0.004). We confirmed the T allele association with risk for T2DM after adjusting for possible confound ing variables (OR 2.35; 95% CI [1.28–4.32]; P = 0.006). Interaction analysis showed that the increased risk for T2DM conferred by the T allele is modified by BMI (Pinteraction = 0.008), age (Pinteraction = 0.005) and gender (Pinteraction = 0.026). A T allele protective effect against obesity was observed (OR 0.71; 95% CI [0.54–0.94]; P = 0.016). The C allele increased obesity risk (OR 1.40; 95% CI [1.06–1.84]; P = 0.017) and the CC genotype showed a borderline association with abdominal obesity risk (OR 1.28; 95% CI [1.06–1.67]; P = 0.045). The CC genotype increased the obesity risk factor after adjusting for possible confounding variables (OR 1.41; 95% CI [1.06–1.86]; P = 0.017). An increase of the TT genotype in the second tertile of ∆BMI values was observed in participants without type 2 diabetes (OR 5.13; 95% CI [1.40–18.93]; P = 0.009) in the recessive genetic model. Conclusion We confirmed that the rs7903146 is both associated with T2DM and obesity. The TCF7L2 rs7903146 T allele increased T2DM risk in the normal weight group and interacted with sex, age and BMI, while the C allele increased obesity risk. The TT genotype was associated with a lesser extent of BMI variation over the SABE study’s 10-year period.

Human longevity is a polygenic and multifactorial trait. Pathways related to lifespan are complex and involve molecular, cellular, and environmental processes. In this analytical observational study, we evaluated the relationship between environment factors, oxidative stress status, DNA integrity level, and the association of FOXO3 (rs2802292), SOD2 (rs4880), APOE (rs429358 and rs7412), and SIRT1 (rs2273773) polymorphisms with longevity in oldest-old individuals from southeastern Brazil. We found an association between the FOXO3 GG genotype and gender. While lifestyle, anthropometric, and biochemical characteristics showed significant results, DNA damage and oxidative stress were not related to lifespan. We found that long-lived individuals with FOXO3 GT genotype had low levels of triglycerides. This study is the first to demonstrate that FOXO3 could be a candidate gene for longevity in the Brazilian population. These results are important in terms of provisions of health care for age-related diseases and lifespan, and provide insight for further research on epigenetic, gene regulation, and expression in oldest-old individuals.