Combined Effects of Alzheimer Risk Variants in theCLUandApoEGenes on Ventricular Expansion Patterns in the Elderly

• DOI: 10.1523/jneurosci.5236-13.2014
• Publication Date: 2014-05-07T17:38:19Z
• Authors: Florence F. Rouss...; Boris A. Gutman; Sarah K. Madsen; John B. Colby; Paul M. Thompson
• Keywords: Male; Risk; Aging; Brain Mapping; Genotype; DNA; Real-Time Polymerase Chain Reaction; Magnetic Resonance Imaging; 3. Good health; 03 medical and health sciences; Apolipoproteins E; Clusterin; 0302 clinical medicine; Alzheimer Disease; Lateral Ventricles; Image Processing, Computer-Assisted; Humans; Regression Analysis; Female; Alleles; Aged; Genome-Wide Association Study

The C allele at the rs11136000 locus in the clusterin (CLU) gene is the third strongest known genetic risk factor for late-onset Alzheimer's disease (LOAD). A recent genome-wide association study of LOAD found the strongest evidence of association withCLUat rs1532278, in high linkage disequilibrium with rs11136000. Brain structure and function are related to theCLUrisk alleles, not just in LOAD patients but also in healthy young adults. We tracked the volume of the lateral ventricles across baseline, 1-year, and 2-year follow-up scans in a large sample of elderly human participants (N= 736 at baseline), from the Alzheimer's Disease Neuroimaging Initiative, to determine whether theseCLUrisk variants predicted longitudinal ventricular expansion. The rs11136000 major C allele—previously linked with reducedCLUexpression and with increased risk for dementia—predicted faster expansion, independently of dementia status orApoEgenotype. Further analyses revealed that theCLUandApoErisk variants had combined effects on both volumetric expansion and lateral ventricle surface morphology. The rs1532278 locus strongly resembles a regulatory element. Its association with ventricular expansion was slightly stronger than that of rs11136000 in our analyses, suggesting that it may be closer to a functional variant. Clusterin affects inflammation, immune responses, and amyloid clearance, which in turn may result in neurodegeneration. Pharmaceutical agents such as valproate, which counteract the effects of genetically determined reduced clusterin expression, may help to achieve neuroprotection and contribute to the prevention of dementia, especially in carriers of theseCLUrisk variants.