Characteristics of Alzheimer's disease patients with and without ApoE4 allele

Recommended cognitive outcomes in preclinical Alzheimer's disease: Consensus statement from the European Prevention of Alzheimer's Dementia project

The Horizon 2020/IMI European Prevention of Alzheimer's Dementia (EPAD) project will undertake large-scale proof-of-concept trials in predementia Alzheimer's disease (AD). Within EPAD, the monitoring of cognitive trajectories in the preclinical period will constitute a central outcome measure; however, there are currently no clear guidelines as to how this should be achieved as most measures have been developed for the period around dementia diagnosis. The EPAD Scientific Advisory Group for Clinical and Cognitive Outcomes identified appropriate cognitive measures based on a literature search covering both cognitive correlates of preclinical brain changes from imaging studies and cognitive changes observed over time in nondementia population cohorts developing incident dementia. These measures were evaluated according to the following criteria: validity, coherence with biomarker changes, psychometric properties, cross-cultural suitability, availability of alternative forms, and normative data limited practice effects. The resulting consensus statement provides recommendations for both future drug trials and research into preclinical Alzheimer's disease.

An association analysis of Alzheimer disease candidate genes detects an ancestral risk haplotype clade in ACE and putative multilocus association between ACE, A2M, and LRRTM3

Alzheimer's disease (AD) is the most common form of progressive dementia in the elderly. It is a neurodegenerative disorder characterized by the neuropathologic findings of neurofibrillary tangles and amyloid plaques that accumulate in vulnerable brain regions. AD etiology has been studied by many groups, but since the discovery of the APOE epsilon4 allele, no further genes have been mapped conclusively to late-onset AD (LOAD). In this study, we examined genetic association with LOAD susceptibility in 738 Caucasian families (4,704 individuals) and an independent case-control dataset with 296 cases and 566 controls exploring 11 candidate genes (47 SNPs common to both samples). In addition to tests for main effects and haplotypes, the MDR-PDT was used to search for gene-gene interactions in the family data. We observed significant haplotype effects in ACE in family and case-control samples using standard and cladistic haplotype models. ACE was also part of significant 2 and 3-locus MDR-PDT joint effects models with Alpha-2-Macroglobulin (A2M), which mediates the clearance of Abeta, and Leucine-Rich Repeat Transmembrane-3 (LRRTM3), a nested gene in Alpha-3 Catenin (CTNNA3) which binds Presenilin-1. This result did not replicate in the case-control sample, and may not be a true positive. These genes are related to Abeta clearance; thus this constellation of effects might constitute an axis of susceptibility for LOAD. The consistent ACE haplotype result between independent family-based and unrelated case-control datasets is strong evidence in favor of ACE as a susceptibility locus for AD, and replicates results from several other studies in a large sample.

Problems and Solutions in the Genetic Analysis of Late-Onset Alzheimer’s Disease

The identification of the apolipoprotein E gene as a risk factor for late-onset Alzheimer's disease was a spectacularly successful application of genetic analysis to a complex trait, and it led to the hope and expectation that other risk loci for the disease would soon be forthcoming. Twelve years later, despite a huge amount of work, no other loci have been identified. In this article, we discuss the complexity of the problem and the pitfalls in the analytical methods that have been used and how we are approaching this problem.