scholarly journals Genetic Analysis of Case/Control Data Using Estimated Haplotype Frequencies: Application to APOE Locus Variation and Alzheimer's Disease

2001 ◽  
Vol 11 (1) ◽  
pp. 143-151 ◽  
Author(s):  
D. Fallin
2007 ◽  
Vol 28 (1) ◽  
pp. 18.e1-18.e4 ◽  
Author(s):  
Lars Bertram ◽  
Monica Hsiao ◽  
Matthew B. McQueen ◽  
Michele Parkinson ◽  
Kristina Mullin ◽  
...  

Author(s):  
Trang Mai Tong ◽  
Thuy Thi Hong Dao ◽  
Loc Phuoc Doan ◽  
Dat Thanh Nguyen ◽  
Quynh-Tho Thi Nguyen ◽  
...  

2021 ◽  
Vol 749 ◽  
pp. 135710
Author(s):  
Lifei Xu ◽  
Qiuping Dong ◽  
Liben Xu ◽  
Wei Zou ◽  
Hui Li

Author(s):  
Natalia Bezuch ◽  
Steven Bradburn ◽  
Andrew C. Robinson ◽  
Neil Pendleton ◽  
Antony Payton ◽  
...  

Background: The APOE ɛ4 allele is the strongest known genetic risk factor for sporadic Alzheimer’s disease (AD). The neighboring TOMM40 gene has also been implicated in AD due to its close proximity to APOE. Objective: Here we tested whether methylation of the TOMM40-APOE locus may influence ApoE protein levels and AD pathology. Methods: DNA methylation levels across the TOMM40-APOE locus and ApoE levels were measured in superior frontal gyrus tissues of 62 human brains genotyped for APOE and scored for AD neuropathology. Results: Methylation levels within the TOMM40 CpG island in the promoter or APOE CpG island in Exon 4 did not differ between APOE ɛ4 carriers versus non-carriers. However, APOE ɛ4 carriers had significantly higher methylation the APOE promoter compared with non-carriers. Although DNA methylation at TOMM40, APOE promoter region, or APOE did not differ between AD pathological groups, there was a negative association between TOMM40 methylation and CERAD scores. ApoE protein concentrations did not significantly different between APOE ɛ4 carriers and non-carriers, or between AD pathological groups. Finally, there was no correlation between ApoE protein concentrations and DNA methylation levels. Conclusion: APOE gene methylation may not be affected by genotype, relate to AD pathology or ApoE protein levels in the superior frontal gyrus, though, DNA methylation at the ApoE promoter differed between genotype. DNA methylation at TOMM40 associated with amyloid-β plaques and longitudinal fluid intelligence. In sum, these results suggest a complicated regulation of the TOMM40-APOE locus in the brain in controlling ApoE protein levels and AD neuropathology.


2012 ◽  
Vol 11 (11) ◽  
pp. 1389-1403 ◽  
Author(s):  
Romain Simon ◽  
Marion Girod ◽  
Catherine Fonbonne ◽  
Arnaud Salvador ◽  
Yohann Clément ◽  
...  

Allelic polymorphism of the apolipoprotein E (ApoE) gene (ApoE ε2, ApoE ε3 and ApoE ε4 alleles) gives rise to three protein isoforms (ApoE2, ApoE3 and ApoE4) that differ by 1 or 2 amino acids. Inheritance of the ApoE ε4 allele is a risk factor for developing Alzheimer's disease (AD). The potential diagnostic value of ApoE protein levels in biological fluids (i.e. cerebrospinal fluid, plasma and serum) for distinguishing between AD patients and healthy elderly subjects is subject to great controversy. Although a recent study reported subnormal total ApoE and ApoE4 levels in the plasma of AD patients, other studies have found normal or even elevated protein levels (versus controls). Because all previously reported assays were based on immunoenzymatic techniques, we decided to develop an orthogonal assay based on targeted mass spectrometry by tracking (i) a proteotypic peptide common to all ApoE isoforms and (ii) a peptide that is specific for the ε4 allele. After trypsin digestion, the ApoE4-specific peptide contains an oxidation-prone methionine residue. The endogenous methionine oxidation level was evaluated in a small cohort (n = 68) of heterozygous ε3ε4 carriers containing both healthy controls and AD patients. As expected, the proportion of oxidized residues varied from 0 to 10%, with an average of 5%. We therefore developed a standardized strategy for the unbiased, absolute quantification of ApoE4, based on performic acid oxidization of methionine. Once the sample workflow had been thoroughly validated, it was applied to the concomitant quantification of total ApoE and ApoE4 isoform in a large case-control study (n = 669). The final measurements were consistent with most previously reported ApoE concentration values and confirm the influence of the different alleles on the protein expression level. Our results illustrate (i) the reliability of selected reaction monitoring-based assays and (ii) the value of the oxidization step for unbiased monitoring of methionine-containing proteotypic peptides. Furthermore, a statistical analysis indicated that neither total ApoE and ApoE4 levels nor the ApoE/ApoE4 ratio correlated with the diagnosis of AD. These findings reinforce the conclusions of previous studies in which plasma ApoE levels had no obvious clinical significance.


2002 ◽  
Vol 21 (2) ◽  
pp. 81-86 ◽  
Author(s):  
C. Wolfson ◽  
A. Perrault ◽  
Y. Moride ◽  
J.M. Esdaile ◽  
L. Abenhaim ◽  
...  

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