title: Combined effects of Alzheimer risk variants in the CLU and ApoE genes on ventricular expansion patterns in the elderly.
abstract: 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 with CLU at rs1532278, in high linkage disequilibrium with rs11136000. Brain structure and function are related to the CLU risk 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 these CLU risk variants predicted longitudinal ventricular expansion. The rs11136000 major C allele-previously linked with reduced CLU expression and with increased risk for dementia-predicted faster expansion, independently of dementia status or ApoE genotype. Further analyses revealed that the CLU and ApoE risk 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 these CLU risk variants.
authors.affiliation: Department of Neurology, and Department of Psychiatry, Semel Institute, David Geffen School of Medicine, University of California, Los Angeles, Los Angeles, California 90095, Imaging Genetics Center, and Departments of Neurology, and Psychiatry, Radiology, Engineering, Pediatrics, and Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033.
authors.forename: Florence F
authors.initials: FF
authors.lastname: Roussotte
authors.forename: Boris A
authors.initials: BA
authors.lastname: Gutman
authors.forename: Sarah K
authors.initials: SK
authors.lastname: Madsen
authors.forename: John B
authors.initials: JB
authors.lastname: Colby
authors.forename: Paul M
authors.initials: PM
authors.lastname: Thompson
mesh_terms: D000368:Aged; D000375:Aging / Q000502:physiology; D000483:Alleles; D000544:Alzheimer Disease / Q000235:genetics*; D001057:Apolipoproteins E / Q000235:genetics*; D001931:Brain Mapping; D051152:Clusterin / Q000235:genetics*; D004247:DNA / Q000235:genetics; D005260:Female; D055106:Genome-Wide Association Study; D005838:Genotype; D006801:Humans; D007091:Image Processing, Computer-Assisted; D020547:Lateral Ventricles / Q000502:physiology*; D008279:Magnetic Resonance Imaging; D008297:Male; D060888:Real-Time Polymerase Chain Reaction; D012044:Regression Analysis; D012306:Risk
chemical_list: D001057:Apolipoproteins E; D051152:Clusterin; D004247:DNA
keywords: ApoE; brain aging; clusterin; genetics; neuroimaging; ventricular expansion