The overall aim of this project is to determine the contribution of genetic variants to age at onset and risk of Alzheimer's disease (AD) in adults with Down syndrome (DS). Linkage and association studies have provided evidence for significant genetic influences on risk for AD, but the role for most of these genetic factors has not been investigated in adults with DS. Adults with DS over-express the p amyloid precursor protein (APP), have early onset of AD neuropathology and high risk for dementia. However, there is a wide range of age at onset of AD and not all adults with DS develop AD, suggesting the importance of additional determinants of risk. In previous work, we made several key observations that support the hypothesis that genetic and environmental factors can contribute to age at onset and risk of AD in DS. We propose now to determine the contribution of genetic variants that may influence cognitive function, risk for AD, age at onset of AD, and differences in AB peptide levels in a large cohort of adults with DS from our current project. We will take advantage of the deep phenotyping and repeated assessments that have been accomplished since the inception of this study. The cohort has completed up to 6 follow-up assessments and we have a large sample of incident AD cases whose onset and progression has been well documented. We have stored DNA, neuropsychological and functional status test scores, medical history, AP peptide levels, and dementia status on 366 men and women with DS and will recruit and follow an additional 150 nondemented participants in conjunction with Subprojects 1 and 2. Thus, we are in a unique position to relate genetic variants to a range of AD-related phenotypes. We will conduct an analysis of a broad panel of candidate genes for AD in adults with DS. We will fine map candidate genes using the lllumina GoldenGate custom array. Analyses will focus first on variants which have been identified in prior genome wide linkage or association studies, in meta-analyses, and that have been implicated in AD pathogenesis, including regions that are biologically important to screen, as well as candidate genes on chromosome 21 which are triplicated in adults with DS. We will perform allelic and genotypic association studies to identify polymorphisms that confer the strongest influence on (1) risk for AD;(2) age at onset of AD;(3) levels and rate of change in AB peptides in demented and nondemented adults;and (4) cognitive function. Then we will use the SNPs with robust significant associations with AD to confirm the associations in independent replication datasets, first in a large well characterized cohort of adults with DS and then in non-DS cohorts from the National Institute on Aging- Late Onset Alzheimer's Disease Study (NIA-LOAD). We will relate variants in genes identified in Dr. Tycko's epigenetic project to blood-related phenotypes.

Agency
National Institute of Health (NIH)
Institute
Eunice Kennedy Shriver National Institute of Child Health & Human Development (NICHD)
Type
Research Program Projects (P01)
Project #
5P01HD035897-25
Application #
8471138
Study Section
Special Emphasis Panel (ZHD1-MRG-C)
Project Start
Project End
Budget Start
2013-06-01
Budget End
2014-05-31
Support Year
25
Fiscal Year
2013
Total Cost
$220,627
Indirect Cost
$11,177
Name
Hugo W. Moser Research Institute Kennedy Krieger
Department
Type
DUNS #
155342439
City
Baltimore
State
MD
Country
United States
Zip Code
21205
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Mendioroz, Maite; Do, Catherine; Jiang, Xiaoling et al. (2015) Trans effects of chromosome aneuploidies on DNA methylation patterns in human Down syndrome and mouse models. Genome Biol 16:263
Schupf, Nicole; Lee, Annie; Park, Naeun et al. (2015) Candidate genes for Alzheimer's disease are associated with individual differences in plasma levels of beta amyloid peptides in adults with Down syndrome. Neurobiol Aging 36:2907.e1-10
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Krinsky-McHale, Sharon J; Silverman, Wayne; Gordon, James et al. (2014) Vision deficits in adults with Down syndrome. J Appl Res Intellect Disabil 27:247-63
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Esbensen, Anna J; Mailick, Marsha R; Silverman, Wayne (2013) Long-term impact of parental well-being on adult outcomes and dementia status in individuals with Down syndrome. Am J Intellect Dev Disabil 118:294-309
Janicki, S C; Park, N; Cheng, R et al. (2013) Aromatase variants modify risk for Alzheimer's disease in a multiethnic female cohort. Dement Geriatr Cogn Disord 35:340-6
Xing, Luzhou; Salas, Martha; Zhang, Hong et al. (2013) Creation and characterization of BAC-transgenic mice with physiological overexpression of epitope-tagged RCAN1 (DSCR1). Mamm Genome 24:30-43

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