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Dried Blood Spot Collection of Health Biomarkers to Maximize Participation in Population Studies
Published on: January 28, 2014
Biomarkers
Beatriz Ramos Lucente1, Isadora Cristina Ribeiro2, Luis E Santos3
1UNICAMP, Jundiaí, São Paulo, Brazil.
Background:
Alzheimer's disease (AD) is the most prevalent neurodegenerative disorder, and ApoE ε4 allele is the most relevant genetic risk factor for sporadic AD. Although it is well-known that ApoE ε4 is related to brain amyloidosis, much less is known whether this genetic risk factor may influence Aβ and tau plasmatic levels in the mildest clinical phase: mild cognitive impairment (MCI) and subjective cognitive decline (SCD). We evaluated if plasmatic (Aβ40, Aβ42, p-tau181 e t-tau) and cerebrospinal fluid (CSF) (Aβ42, ptau-181, ptau-231 and t-tau) biomarkers differed in patients considering different APOE genotypes (ε2ε3, ε3ε3 and ε3ε4).
Method:
64 older adults (MCI: 36, SCD: 12, AD: 3, control: 13), mean age: 66± 6.6 years old, underwent blood and CSF tests. Roche's Elecsys electrochemiluminescence immunoassay measured the quantification of CSF t-Tau, p-Tau 181, and Aβ42 proteins. Plasma biomarkers Aβ42, Aβ40, p-Tau 181, and t-Tau were measured on an automated SIMOA HD-X immunoassay equipment. Real-time PCR amplification was performed using the 7500 System software (Thermo Fisher Scientific). The APOE genotype determination was based on analyzing single nucleotide polymorphisms rs429358 and rs7412. ANOVA evaluated differences between groups with Bonferroni's post hoc test. Significance was set at p < 0.05.
Result:
We found that the ApoE ε3ε4 group had a lower concentration of CSF Aβ42 than the ε2ε3, p = 0.02. No differences were found in plasmatic levels of any AD biomarkers.
Conclusion:
Plasmatic AD biomarkers did not differ regarding APOE genotype in our sample, but we find a difference in CSF biomarker and the APOE genotype. So, our findings confirm the influence of APOE ε4 allele in central nervous system amyloid levels.
Insights
The APOE ε4 allele, a key Alzheimer's risk factor, influences cerebrospinal fluid (CSF) amyloid levels but not plasma biomarkers in individuals with mild cognitive impairment or subjective cognitive decline.
Area of Science:
- Neuroscience
- Genetics
- Biomarker Research
Background:
- Alzheimer's disease (AD) is the most common neurodegenerative disorder.
- The APOE ε4 allele is the primary genetic risk factor for sporadic AD.
- The influence of APOE ε4 on amyloid-beta (Aβ) and tau levels in early cognitive decline stages remains unclear.
Purpose of the Study:
- To investigate the association between APOE genotypes and levels of plasma and CSF biomarkers (Aβ40, Aβ42, p-tau181, t-tau).
- To determine if APOE genotype impacts biomarker concentrations in individuals with mild cognitive impairment (MCI) and subjective cognitive decline (SCD).
Main Methods:
- Analyzed plasma and CSF samples from 64 older adults (MCI, SCD, AD, controls).
- Quantified Aβ42, Aβ40, p-tau181, and t-tau using electrochemiluminescence and SIMOA immunoassays.
- Determined APOE genotype via SNP analysis and assessed biomarker differences using ANOVA with Bonferroni correction.
Main Results:
- Individuals with the APOE ε3ε4 genotype exhibited lower CSF Aβ42 concentrations compared to the ε2ε3 genotype (p=0.02).
- No significant differences in plasma Aβ40, Aβ42, p-tau181, or t-tau levels were observed across APOE genotypes.
Conclusions:
- APOE genotype does not influence peripheral AD biomarker levels in this cohort.
- The APOE ε4 allele is associated with altered central nervous system amyloid levels, specifically reduced CSF Aβ42.
- Findings confirm the role of APOE ε4 in modulating central amyloid pathology even in early cognitive decline stages.
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