- Email: [email protected]
Characterization of brain region- and disease-specific IDE expression in Alzheimer patients and controls
Poster Presentations P1
S202
2.6 (95% CI: 1.2-5.2), and one copy with a risk ratio of 1.9 (95% CI: 1.1-3.4). Moreover, two adjacent SNPs, rs6163 and rs743572, had similar genotype risk ratios as rs10786712, suggesting that the region flanking rs10786712 may harbor risk variants. Conclusions: We report that the variants at CYP17 decrease age at onset and increase the likelihood of AD in high risk women with DS, independent of BMI, ethnicity, level of intellectual disability, and APOE. We are currently examining the relation between risk SNPs and multiple sex hormone levels to further understand this association.
P1-095
CHARACTERIZATION OF BRAIN REGION- AND DISEASE-SPECIFIC IDE EXPRESSION IN ALZHEIMER PATIENTS AND CONTROLS
Richard J. Miles1,*, Anthony DelleDonne1,*, Fanggeng Zou1, Melissa Murray1, Li Ma1, Thuy Nguyen1, Gina Bisceglio1, Dennis W. Dickson1, Steven Younkin1, Malcolm A. Leissring1, Nilufer Ertekin-Taner1,2, 1Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA; 2Department of Neurology, Mayo Clinic, Jacksonville, FL, USA. Contact e-mail: [email protected] Background: Insulin-degrading enzyme (IDE) is a zinc-metalloprotease that can degrade amyloid b (Ab) and influence its levels in the brain. Previous studies identified brain-region and disease-specific differences in IDE protein and mRNA expression in the human brain, though there is lack of consensus in regards to the presence and direction of these effects. Methods: Using a mouse monoclonal antibody against IDE, we stained paraffin-embedded sections from ADs (7 cerebella, 8 superior temporal cortex) and non-ADs (8 cerebella and 8 superior temporal cortex). We performed quantitative immunohistochemistry focused on the whole section, gray matter and white matter, separately. We measured IDE mRNA levels from the cerebella (191 ADs and 190 non-ADs) and temporal cortex (100 ADs and 100 nonADs), using quantitative PCR. Results: There was significantly increased IDE protein (p < 0.005-0.001) and mRNA (p < 0.0001) in the cerebellum compared with the temporal cortex in both AD and non-AD brains. There was significant increase in IDE mRNA levels in the AD vs. non-AD cerebella (p ¼ 0.0005) even after controlling for age, gender and ApoE, however no significant difference was detected in the temporal cortex. We also did not detect a significant difference in IDE protein expressions in ADs vs. nonADs in either brain region, though our sample size was limited. Conclusions: These results suggest that there likely exists brain region-specific influence on IDE mRNA and protein expression that may not be solely attributed to AD pathology, given that the cerebellum, which is least affected in AD, shows higher IDE expression than the vulnerable temporal cortex. Though speculative, this could be one reason underlying resistance of the cerebellum to AD pathology. Similarly, there appears to be disease-specific elevations in IDE mRNA in AD cerebella, though this cannot be explained based on regional influence by AD pathology. Upregulation of IDE expression via pathology elsewhere in the brain could underlie these findings. Studies to correlate AD pathology with IDE expression in our series are currently underway.
P1-096
TOMM40, APOE, AND AGE OF ONSET OF ALZHEIMER’S DISEASE
Richard J. Caselli1, Ann Saunders2, Michael Lutz2, Matthew Huentelman3, Eric Reiman4, Allen Roses2, 1Mayo Clinic Scottsdale, Scottsdale, AZ, USA; 2 Deane Drug Discovery Institute at Duke University, Durham, NC, USA; 3 Translational Genomics Research Institute, Phoenix, AZ, USA; 4Banner Alzheimer Institute, Phoenix, AZ, USA. Contact e-mail: Caselli.Richard@ Mayo.edu Background: A variable-length poly-T variant within intron 6 of the TOMM40 gene was found to correlate with the retrospectively determined age of Alzheimer’s disease (AD) onset (Roses AD et al, 2009). TOMM40 encodes the translocase of the outer mitochondrial membrane pore subunit. Longer TOMM40 poly-T lengths (L) are associated with earlier age of AD
onset than shorter TOMM40 (S) lengths. Because retrospective estimation of age of onset can be unreliable, we correlated TOMM40 genotype with prospectively determined age of onset of incident mild cognitive impairment (MCI) and AD to test the hypothesis that the TOMM40 L variant is associated with a younger age of symptomatic AD onset. Methods: Cognitively normal residents of Maricopa County age 21 years and older were recruited through local media ads into either the Arizona APOE cohort, a longitudinal study of cognitive aging or the Arizona Alzheimer’s Disease Center cohort (Caselli RJ et al, 2009). The APOE-TOMM40 region was sequenced by Polymorphic DNA Technologies (Alameda, CA). TOMM40 poly-T lengths were converted to genotypes: short poly-T (14-20 T residues) ¼ S, and long poly-T (21 T residues) ¼ L. Symptom surveys, neurologic exams, and neuropsychological tests were repeated every 1-2 years. MCI and AD diagnoses met published diagnostic criteria. Of 37 incident cases of MCI and AD, DNA was available and sequenced in 30. Results: Mean age of neuropsychologically confirmed symptomatic onset was 77.3 +/- 10.6 years that occurred 58.9 +/40.5 months after study entry. Incident MCI and AD subjects included 7 APOE e4/4’s (all TOMM40 LL’s, onset age 69 6 6),10 APOE e3/4’s (6 LL’s, 4 SL’s, onset ages 73 6 9 and 84 6 4), 11 APOE e3/3’s (3 LL’s, 8 SL’s, onset ages 79 6 18 and 83 6 11 at clinical onset), and 2 APOE e2/3’s (1 LL, 1 SL, onset ages 90 and 77). As predicted, LL’s had a younger mean age at clinical onset than SL’s in the overall group (73 6 11 vs. 82 6 9 years, p ¼ 0.02). Additional cases are needed to test the association in APOE subgroups. Conclusions: The LL TOMM40 genotype was associated with younger age of incident MCI and AD onset compared to the SL genotype. A larger confirmatory study is underway.
P1-097
IDENTIFYING COPY NUMBER VARIATION INFLUENCING RISK FOR ALZHEIMER’S DISEASE IN THE AMISH
O. J. Veatch1, D. R. Velez Edwards2, W. K. Scott2, J. R. Gilbert2, M. A. Pericak-Vance2, J. L. Haines1, N. Schnetz-Boutaud1, 1Center for Human Genetics Research, Department of Molecular Physiology & Biophysics, Vanderbilt University Medical School, Nashville, TN, USA; 2J.P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA. Contact e-mail: olivia.j.veatch@vanderbilt. edu Background: Numerous studies have shown that Alzheimer disease (AD) has a high degree of heritability suggesting strong genetic components influencing risk for developing the disease. However, the heterogeneous nature of the disease has made it difficult to identify the underlying genetic loci for AD. Current studies of human Copy Number Variations (CNVs) indicate these structural variations contribute significantly to genetic and allelic heterogeneity. CNVs affect gene function in many ways including deletion or amplification of regions containing variable numbers of genes that could influence neuropsychiatric disease susceptibility. Large-scale CNV studies require stringent control for population stratification to avoid false positive associations. To avoid issues arising from admixture we ascertained subjects from Amish communities located in Indiana and Ohio assuming similar genetic substructure. Methods: To assess possible CNVs influencing AD, a total of 846 male and female individuals (113 affected, 466 unaffected, 267 unknowns) age > ¼ 65 years from this population were genotyped on an AffymetrixÒ SNP 6.0 microarray chip. Each individual was assessed for CNVs using both PartekÒ Genomics Suite and PennCNVÒ software. CNVs unique to individuals comprising the Amish dataset were detected by both programs using an unpaired analysis using a hidden Markov Model and the baseline provided by AffymetrixÒ, specific for the SNP6.0 array chip. Results: Results from each separate analysis were evaluated and CNV regions that were detected by both programs, covering the same chromosomal location, were identified. A total of 72,002 regions across the genome were found to be variable in our Amish dataset. Of these, 203 CNVs were detected in at least 30 individuals, and thus are common to the Amish population. Conclusions: Preliminary analysis suggests that none of these common CNVs are strongly associated with AD, but more detailed analyses and molecular confirmation are ongoing. We are also identifying candidate disease-susceptibility genes located in these regions.
S202
2.6 (95% CI: 1.2-5.2), and one copy with a risk ratio of 1.9 (95% CI: 1.1-3.4). Moreover, two adjacent SNPs, rs6163 and rs743572, had similar genotype risk ratios as rs10786712, suggesting that the region flanking rs10786712 may harbor risk variants. Conclusions: We report that the variants at CYP17 decrease age at onset and increase the likelihood of AD in high risk women with DS, independent of BMI, ethnicity, level of intellectual disability, and APOE. We are currently examining the relation between risk SNPs and multiple sex hormone levels to further understand this association.
P1-095
CHARACTERIZATION OF BRAIN REGION- AND DISEASE-SPECIFIC IDE EXPRESSION IN ALZHEIMER PATIENTS AND CONTROLS
Richard J. Miles1,*, Anthony DelleDonne1,*, Fanggeng Zou1, Melissa Murray1, Li Ma1, Thuy Nguyen1, Gina Bisceglio1, Dennis W. Dickson1, Steven Younkin1, Malcolm A. Leissring1, Nilufer Ertekin-Taner1,2, 1Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA; 2Department of Neurology, Mayo Clinic, Jacksonville, FL, USA. Contact e-mail: [email protected] Background: Insulin-degrading enzyme (IDE) is a zinc-metalloprotease that can degrade amyloid b (Ab) and influence its levels in the brain. Previous studies identified brain-region and disease-specific differences in IDE protein and mRNA expression in the human brain, though there is lack of consensus in regards to the presence and direction of these effects. Methods: Using a mouse monoclonal antibody against IDE, we stained paraffin-embedded sections from ADs (7 cerebella, 8 superior temporal cortex) and non-ADs (8 cerebella and 8 superior temporal cortex). We performed quantitative immunohistochemistry focused on the whole section, gray matter and white matter, separately. We measured IDE mRNA levels from the cerebella (191 ADs and 190 non-ADs) and temporal cortex (100 ADs and 100 nonADs), using quantitative PCR. Results: There was significantly increased IDE protein (p < 0.005-0.001) and mRNA (p < 0.0001) in the cerebellum compared with the temporal cortex in both AD and non-AD brains. There was significant increase in IDE mRNA levels in the AD vs. non-AD cerebella (p ¼ 0.0005) even after controlling for age, gender and ApoE, however no significant difference was detected in the temporal cortex. We also did not detect a significant difference in IDE protein expressions in ADs vs. nonADs in either brain region, though our sample size was limited. Conclusions: These results suggest that there likely exists brain region-specific influence on IDE mRNA and protein expression that may not be solely attributed to AD pathology, given that the cerebellum, which is least affected in AD, shows higher IDE expression than the vulnerable temporal cortex. Though speculative, this could be one reason underlying resistance of the cerebellum to AD pathology. Similarly, there appears to be disease-specific elevations in IDE mRNA in AD cerebella, though this cannot be explained based on regional influence by AD pathology. Upregulation of IDE expression via pathology elsewhere in the brain could underlie these findings. Studies to correlate AD pathology with IDE expression in our series are currently underway.
P1-096
TOMM40, APOE, AND AGE OF ONSET OF ALZHEIMER’S DISEASE
Richard J. Caselli1, Ann Saunders2, Michael Lutz2, Matthew Huentelman3, Eric Reiman4, Allen Roses2, 1Mayo Clinic Scottsdale, Scottsdale, AZ, USA; 2 Deane Drug Discovery Institute at Duke University, Durham, NC, USA; 3 Translational Genomics Research Institute, Phoenix, AZ, USA; 4Banner Alzheimer Institute, Phoenix, AZ, USA. Contact e-mail: Caselli.Richard@ Mayo.edu Background: A variable-length poly-T variant within intron 6 of the TOMM40 gene was found to correlate with the retrospectively determined age of Alzheimer’s disease (AD) onset (Roses AD et al, 2009). TOMM40 encodes the translocase of the outer mitochondrial membrane pore subunit. Longer TOMM40 poly-T lengths (L) are associated with earlier age of AD
onset than shorter TOMM40 (S) lengths. Because retrospective estimation of age of onset can be unreliable, we correlated TOMM40 genotype with prospectively determined age of onset of incident mild cognitive impairment (MCI) and AD to test the hypothesis that the TOMM40 L variant is associated with a younger age of symptomatic AD onset. Methods: Cognitively normal residents of Maricopa County age 21 years and older were recruited through local media ads into either the Arizona APOE cohort, a longitudinal study of cognitive aging or the Arizona Alzheimer’s Disease Center cohort (Caselli RJ et al, 2009). The APOE-TOMM40 region was sequenced by Polymorphic DNA Technologies (Alameda, CA). TOMM40 poly-T lengths were converted to genotypes: short poly-T (14-20 T residues) ¼ S, and long poly-T (21 T residues) ¼ L. Symptom surveys, neurologic exams, and neuropsychological tests were repeated every 1-2 years. MCI and AD diagnoses met published diagnostic criteria. Of 37 incident cases of MCI and AD, DNA was available and sequenced in 30. Results: Mean age of neuropsychologically confirmed symptomatic onset was 77.3 +/- 10.6 years that occurred 58.9 +/40.5 months after study entry. Incident MCI and AD subjects included 7 APOE e4/4’s (all TOMM40 LL’s, onset age 69 6 6),10 APOE e3/4’s (6 LL’s, 4 SL’s, onset ages 73 6 9 and 84 6 4), 11 APOE e3/3’s (3 LL’s, 8 SL’s, onset ages 79 6 18 and 83 6 11 at clinical onset), and 2 APOE e2/3’s (1 LL, 1 SL, onset ages 90 and 77). As predicted, LL’s had a younger mean age at clinical onset than SL’s in the overall group (73 6 11 vs. 82 6 9 years, p ¼ 0.02). Additional cases are needed to test the association in APOE subgroups. Conclusions: The LL TOMM40 genotype was associated with younger age of incident MCI and AD onset compared to the SL genotype. A larger confirmatory study is underway.
P1-097
IDENTIFYING COPY NUMBER VARIATION INFLUENCING RISK FOR ALZHEIMER’S DISEASE IN THE AMISH
O. J. Veatch1, D. R. Velez Edwards2, W. K. Scott2, J. R. Gilbert2, M. A. Pericak-Vance2, J. L. Haines1, N. Schnetz-Boutaud1, 1Center for Human Genetics Research, Department of Molecular Physiology & Biophysics, Vanderbilt University Medical School, Nashville, TN, USA; 2J.P. Hussman Institute for Human Genomics, University of Miami Miller School of Medicine, Miami, FL, USA. Contact e-mail: olivia.j.veatch@vanderbilt. edu Background: Numerous studies have shown that Alzheimer disease (AD) has a high degree of heritability suggesting strong genetic components influencing risk for developing the disease. However, the heterogeneous nature of the disease has made it difficult to identify the underlying genetic loci for AD. Current studies of human Copy Number Variations (CNVs) indicate these structural variations contribute significantly to genetic and allelic heterogeneity. CNVs affect gene function in many ways including deletion or amplification of regions containing variable numbers of genes that could influence neuropsychiatric disease susceptibility. Large-scale CNV studies require stringent control for population stratification to avoid false positive associations. To avoid issues arising from admixture we ascertained subjects from Amish communities located in Indiana and Ohio assuming similar genetic substructure. Methods: To assess possible CNVs influencing AD, a total of 846 male and female individuals (113 affected, 466 unaffected, 267 unknowns) age > ¼ 65 years from this population were genotyped on an AffymetrixÒ SNP 6.0 microarray chip. Each individual was assessed for CNVs using both PartekÒ Genomics Suite and PennCNVÒ software. CNVs unique to individuals comprising the Amish dataset were detected by both programs using an unpaired analysis using a hidden Markov Model and the baseline provided by AffymetrixÒ, specific for the SNP6.0 array chip. Results: Results from each separate analysis were evaluated and CNV regions that were detected by both programs, covering the same chromosomal location, were identified. A total of 72,002 regions across the genome were found to be variable in our Amish dataset. Of these, 203 CNVs were detected in at least 30 individuals, and thus are common to the Amish population. Conclusions: Preliminary analysis suggests that none of these common CNVs are strongly associated with AD, but more detailed analyses and molecular confirmation are ongoing. We are also identifying candidate disease-susceptibility genes located in these regions.