PMCC PMCC

Search tips
Search criteria

Advanced
Results 1-25 (25)
 

Clipboard (0)
None

Select a Filter Below

Journals
more »
Year of Publication
Document Types
1.  Shorter telomeres are associated with obesity and weight gain in the elderly 
Objective
Obesity and shorter telomeres are commonly associated with elevated risk for age-related diseases and mortality. Whether telomere length (TL) may be associated with obesity or variations in adiposity is not well established. Therefore, we set out to test the hypothesis that TL may be a risk factor for increased adiposity using data from a large population-based cohort study.
Design
Levels of adiposity were assessed in 6 ways (obesity status, body mass index or BMI, the percentage of body fat or % body fat, leptin, visceral and subcutaneous fat mass) in 2,721 elderly subjects (42% black and 58% white). Associations between TL measured in leukocytes at baseline and adiposity traits measured at baseline and 3 of these traits after 7 years of follow-up were tested using regression models adjusting for important covariates. Additionally, we look at weight changes and relative changes in BMI and % body fat between baseline and follow-up.
Results
At baseline, TL was negatively associated with % body fat (β = −0.35 ± 0.09, p = 0.001) and subcutaneous fat (β = −2.66 ± 1.07, p = 0.01), and positively associated with leptin after adjusting for % body fat (β = 0.32 ± 0.14, p = 0.001), but not with obesity, BMI or visceral fat. Prospective analyses showed that longer TL was associated with positive percent change between baseline and 7-year follow-up for both BMI (β = 0.48 ± 0.20, p = 0.01) and % body fat (β = 0.42 ± 0.23, p = 0.05).
Conclusion
Our study suggests that shorter TL may be a risk factor for increased adiposity. Coupling with previous reports on their reversed roles, the relationship between adiposity and TL may be complicated and warrant more prospective studies.
doi:10.1038/ijo.2011.196
PMCID: PMC3408817  PMID: 22005719
Obesity; telomere length; adiposity; telomeres
2.  Association between oxidized LDL, obesity and type 2 diabetes in a population-based cohort, the Health Aging and Body Composition study 
Aims/hypothesis
Accumulating evidence suggests a cross-sectional association between oxidative stress and type 2 diabetes (T2D). Systemic oxidative stress, as measured by oxidized LDL (oxLDL), has been correlated with visceral fat. We examined the relationship between oxLDL, and T2D- and obesity-related traits in a bi-racial sample of 2,985 subjects at baseline and after 7 years of follow-up.
Methods
We examined six T2D-related traits (T2D status, HbA1c, fasting glucose, insulin, adiponectin and HOMA-IR) as well as six obesity-related traits (obesity status, BMI, leptin, % body fat, visceral and subcutaneous fat mass) using logistic and linear regression models.
Results
In all subjects at baseline, oxLDL was positively associated with T2D (OR=1.3,95% CI:1.1–1.5), fasting glucose (β=0.03±0.006), HbA1c (β=0.02±0.004), fasting insulin (β=0.12±0.02), HOMA-IR (β=0.13±0.02) and negatively with adiponectin (β=−0.16±0.03), (all p<0.001). The strength and magnitude of these associations did not differ much between blacks and whites. In both blacks and whites, oxLDL was also associated with obesity (OR=1.3, 95% CI:1.1–1.4) and 3 of its related traits (β=0.60±0.14 for BMI, β=0.74±0.17 for % body fat, β=0.29±0.06 for visceral fat;
all p<0.001). Furthermore, of 4 traits measured after 7 years of follow-up (fasting glucose, HbA1c, BMI and % fat), their relationship with oxLDL were similar to baseline observations. No significant association was found between oxLDL and incident T2D. Interestingly, oxLDL was significantly associated with % change in T2D- and obesity-related traits in whites but not in blacks.
Conclusion/interpretation
Our data suggest that systemic oxidative stress may be a novel risk factor for T2D and obesity.
doi:10.1002/dmrr.1011
PMCID: PMC3269343  PMID: 19780064
oxLDL; diabetes; oxidation; obesity
3.  Diabetes Risk Assessment in Mexicans and Mexican Americans 
Diabetes Care  2010;33(10):2260-2265.
OBJECTIVE
Parental diabetes history is a well-known risk factor for type 2 diabetes and considered strong evidence for a genetic basis of type 2 diabetes. Whether this relationship is affected by other known risk factors, specifically obesity, remains unclear, possibly due to a relative paucity of lean diabetic patients.
RESEARCH DESIGN AND METHODS
This issue was investigated using data from a high-risk population from Mexico (National Health Survey 2000, n = 27,349), with observations replicated using U.S. citizens of Mexican descent from the National Health and Nutrition Examination Survey 2001–2002 and 2003–2004 (n = 1,568).
RESULTS
As expected, positive parental diabetes was a significant risk factor for type 2 diabetes, regardless of age, sex, or adiposity level. However, positive parental diabetes conferred greater risk in leaner individuals than in their overweight peers (P = 0.001). In other words, the effect of BMI on type 2 diabetes risk was smaller in the presence of parental diabetes history.
CONCLUSIONS
These findings suggest that parental diabetes is a stronger risk factor for type 2 diabetes in the absence of obesity. Thus, studies in lean diabetic patients could help identify type 2 diabetes susceptibility genes. This study reinforces the concept that parental diabetes and BMI are independent type 2 diabetes risk factors and suggests that glycemic screening may be helpful in assessing type 2 diabetes risk in individuals with parental diabetes history, regardless of their overweight status.
doi:10.2337/dc10-0992
PMCID: PMC2945171  PMID: 20628089
4.  Association Between Telomere Length, Specific Causes of Death, and Years of Healthy Life in Health, Aging, and Body Composition, a Population-Based Cohort Study 
Although telomere length (TL) is known to play a critical role in cellular senescence, the relationship of TL to aging and longevity in humans is not well understood. In a large biracial population-based cohort, we tested the hypotheses that elderly persons with shorter TL in peripheral white blood cells have poorer survival, shorter life span, and fewer years of healthy life (YHL). Associations were evaluated using Cox proportional hazard models and linear regression analyses where appropriate. TL (in kilo base pairs) was not associated with overall survival (hazard ratio 1.0; 95% confidence interval 0.9–1.1) or death from any specific underlying cause including infectious diseases, cancer, or cardiac and cerebrovascular diseases. TL, however, was positively associated with more YHL (β = 0.08 ± 0.04, p = .03). Findings suggest that TL may not be a strong biomarker of survival in older individuals, but it may be an informative biomarker of healthy aging.
doi:10.1093/gerona/glp061
PMCID: PMC2981462  PMID: 19435951
Telomere; Survival; Life span; Health status; Years of healthy life
5.  A Common Variant in the Telomerase RNA Component Is Associated with Short Telomere Length 
PLoS ONE  2010;5(9):e13048.
Background
Telomeres shorten as cells divide. This shortening is compensated by the enzyme telomerase. We evaluated the effect of common variants in the telomerase RNA component (TERC) gene on telomere length (TL) in the population-based Health Aging and Body Composition (Health ABC) Study and in two replication samples (the TwinsUK Study and the Amish Family Osteoporosis Study, AFOS).
Methodology
Five variants were identified in the TERC region by sequence analysis and only one SNP was common (rs2293607, G/A). The frequency of the G allele was 0.26 and 0.07 in white and black, respectively. Testing for association between TL and rs2293607 was performed using linear regression models or variance component analysis conditioning on relatedness among subjects.
Results
The adjusted mean TL was significantly shorter in 665 white carriers of the G allele compared to 887 non-carriers from the Health ABC Study (4.69±0.05 kbp vs. 4.86±0.04 kbp, measured by quantitative PCR, p = 0.005). This association was replicated in another white sample from the TwinsUK Study (6.90±0.03 kbp in 301 carriers compared to 7.06±0.03 kbp in 395 non-carriers, measured by Southern blots, p = 0.009). A similar pattern of association was observed in whites from the family-based AFOS and blacks from the Health ABC cohort, although not statistically significant, possibly due to the lower allele frequency in these populations. Combined analysis using 2,953 white subjects from 3 studies showed a significant association between TL and rs2293607 (β = −0.19±0.04 kbp, p = 0.001).
Conclusion
Our study shows a significant association between a common variant in TERC and TL in humans, suggesting that TERC may play a role in telomere homeostasis.
doi:10.1371/journal.pone.0013048
PMCID: PMC2946401  PMID: 20885959
6.  Meta-Analysis of Genome-Wide Association Studies in African Americans Provides Insights into the Genetic Architecture of Type 2 Diabetes 
Ng, Maggie C. Y. | Shriner, Daniel | Chen, Brian H. | Li, Jiang | Chen, Wei-Min | Guo, Xiuqing | Liu, Jiankang | Bielinski, Suzette J. | Yanek, Lisa R. | Nalls, Michael A. | Comeau, Mary E. | Rasmussen-Torvik, Laura J. | Jensen, Richard A. | Evans, Daniel S. | Sun, Yan V. | An, Ping | Patel, Sanjay R. | Lu, Yingchang | Long, Jirong | Armstrong, Loren L. | Wagenknecht, Lynne | Yang, Lingyao | Snively, Beverly M. | Palmer, Nicholette D. | Mudgal, Poorva | Langefeld, Carl D. | Keene, Keith L. | Freedman, Barry I. | Mychaleckyj, Josyf C. | Nayak, Uma | Raffel, Leslie J. | Goodarzi, Mark O. | Chen, Y-D Ida | Taylor, Herman A. | Correa, Adolfo | Sims, Mario | Couper, David | Pankow, James S. | Boerwinkle, Eric | Adeyemo, Adebowale | Doumatey, Ayo | Chen, Guanjie | Mathias, Rasika A. | Vaidya, Dhananjay | Singleton, Andrew B. | Zonderman, Alan B. | Igo, Robert P. | Sedor, John R. | Kabagambe, Edmond K. | Siscovick, David S. | McKnight, Barbara | Rice, Kenneth | Liu, Yongmei | Hsueh, Wen-Chi | Zhao, Wei | Bielak, Lawrence F. | Kraja, Aldi | Province, Michael A. | Bottinger, Erwin P. | Gottesman, Omri | Cai, Qiuyin | Zheng, Wei | Blot, William J. | Lowe, William L. | Pacheco, Jennifer A. | Crawford, Dana C. | Grundberg, Elin | Rich, Stephen S. | Hayes, M. Geoffrey | Shu, Xiao-Ou | Loos, Ruth J. F. | Borecki, Ingrid B. | Peyser, Patricia A. | Cummings, Steven R. | Psaty, Bruce M. | Fornage, Myriam | Iyengar, Sudha K. | Evans, Michele K. | Becker, Diane M. | Kao, W. H. Linda | Wilson, James G. | Rotter, Jerome I. | Sale, Michèle M. | Liu, Simin | Rotimi, Charles N. | Bowden, Donald W.
PLoS Genetics  2014;10(8):e1004517.
Type 2 diabetes (T2D) is more prevalent in African Americans than in Europeans. However, little is known about the genetic risk in African Americans despite the recent identification of more than 70 T2D loci primarily by genome-wide association studies (GWAS) in individuals of European ancestry. In order to investigate the genetic architecture of T2D in African Americans, the MEta-analysis of type 2 DIabetes in African Americans (MEDIA) Consortium examined 17 GWAS on T2D comprising 8,284 cases and 15,543 controls in African Americans in stage 1 analysis. Single nucleotide polymorphisms (SNPs) association analysis was conducted in each study under the additive model after adjustment for age, sex, study site, and principal components. Meta-analysis of approximately 2.6 million genotyped and imputed SNPs in all studies was conducted using an inverse variance-weighted fixed effect model. Replications were performed to follow up 21 loci in up to 6,061 cases and 5,483 controls in African Americans, and 8,130 cases and 38,987 controls of European ancestry. We identified three known loci (TCF7L2, HMGA2 and KCNQ1) and two novel loci (HLA-B and INS-IGF2) at genome-wide significance (4.15×10−94
Author Summary
Despite the higher prevalence of type 2 diabetes (T2D) in African Americans than in Europeans, recent genome-wide association studies (GWAS) were examined primarily in individuals of European ancestry. In this study, we performed meta-analysis of 17 GWAS in 8,284 cases and 15,543 controls to explore the genetic architecture of T2D in African Americans. Following replication in additional 6,061 cases and 5,483 controls in African Americans, and 8,130 cases and 38,987 controls of European ancestry, we identified two novel and three previous reported T2D loci reaching genome-wide significance. We also examined 158 loci previously reported to be associated with T2D or regulating glucose homeostasis. While 56% of these loci were shared between African Americans and the other populations, the strongest associations in African Americans are often found in nearby single nucleotide polymorphisms (SNPs) instead of the original SNPs reported in other populations due to differential genetic architecture across populations. Our results highlight the importance of performing genetic studies in non-European populations to fine map the causal genetic variants.
doi:10.1371/journal.pgen.1004517
PMCID: PMC4125087  PMID: 25102180
The pharmacogenomics journal  2013;14(1):6-13.
Variability in response to drug use is common and heritable, suggesting that genome-wide pharmacogenomics studies may help explain the “missing heritability” of complex traits. Here, we describe four independent analyses in 33,781 participants of European ancestry from ten cohorts that were designed to identify genetic variants modifying the effects of drugs on QT interval duration (QT). Each analysis cross-sectionally examined four therapeutic classes: thiazide diuretics (prevalence of use=13.0%), tri/tetracyclic antidepressants (2.6%), sulfonylurea hypoglycemic agents (2.9%), and QT prolonging drugs as classified by the University of Arizona Center for Education and Research on Therapeutics (4.4%). Drug-gene interactions were estimated using covariable adjusted linear regression and results were combined with fixed-effects meta-analysis. Although drug-SNP interactions were biologically plausible and variables were well-measured, findings from the four cross-sectional meta-analyses were null (Pinteraction>5.0×10−8). Simulations suggested that additional efforts, including longitudinal modeling to increase statistical power, are likely needed to identify potentially important pharmacogenomic effects.
doi:10.1038/tpj.2013.4
PMCID: PMC3766418  PMID: 23459443
QT interval; pharmacogenomics; gene-environment interaction
den Hoed, Marcel | Eijgelsheim, Mark | Esko, Tõnu | Brundel, Bianca J J M | Peal, David S | Evans, David M | Nolte, Ilja M | Segrè, Ayellet V | Holm, Hilma | Handsaker, Robert E | Westra, Harm-Jan | Johnson, Toby | Isaacs, Aaron | Yang, Jian | Lundby, Alicia | Zhao, Jing Hua | Kim, Young Jin | Go, Min Jin | Almgren, Peter | Bochud, Murielle | Boucher, Gabrielle | Cornelis, Marilyn C | Gudbjartsson, Daniel | Hadley, David | Van Der Harst, Pim | Hayward, Caroline | Heijer, Martin Den | Igl, Wilmar | Jackson, Anne U | Kutalik, Zoltán | Luan, Jian’an | Kemp, John P | Kristiansson, Kati | Ladenvall, Claes | Lorentzon, Mattias | Montasser, May E | Njajou, Omer T | O’Reilly, Paul F | Padmanabhan, Sandosh | Pourcain, Beate St. | Rankinen, Tuomo | Salo, Perttu | Tanaka, Toshiko | Timpson, Nicholas J | Vitart, Veronique | Waite, Lindsay | Wheeler, William | Zhang, Weihua | Draisma, Harmen H M | Feitosa, Mary F | Kerr, Kathleen F | Lind, Penelope A | Mihailov, Evelin | Onland-Moret, N Charlotte | Song, Ci | Weedon, Michael N | Xie, Weijia | Yengo, Loic | Absher, Devin | Albert, Christine M | Alonso, Alvaro | Arking, Dan E | de Bakker, Paul I W | Balkau, Beverley | Barlassina, Cristina | Benaglio, Paola | Bis, Joshua C | Bouatia-Naji, Nabila | Brage, Søren | Chanock, Stephen J | Chines, Peter S | Chung, Mina | Darbar, Dawood | Dina, Christian | Dörr, Marcus | Elliott, Paul | Felix, Stephan B | Fischer, Krista | Fuchsberger, Christian | de Geus, Eco J C | Goyette, Philippe | Gudnason, Vilmundur | Harris, Tamara B | Hartikainen, Anna-liisa | Havulinna, Aki S | Heckbert, Susan R | Hicks, Andrew A | Hofman, Albert | Holewijn, Suzanne | Hoogstra-Berends, Femke | Hottenga, Jouke-Jan | Jensen, Majken K | Johansson, Åsa | Junttila, Juhani | Kääb, Stefan | Kanon, Bart | Ketkar, Shamika | Khaw, Kay-Tee | Knowles, Joshua W | Kooner, Angrad S | Kors, Jan A | Kumari, Meena | Milani, Lili | Laiho, Päivi | Lakatta, Edward G | Langenberg, Claudia | Leusink, Maarten | Liu, Yongmei | Luben, Robert N | Lunetta, Kathryn L | Lynch, Stacey N | Markus, Marcello R P | Marques-Vidal, Pedro | Leach, Irene Mateo | McArdle, Wendy L | McCarroll, Steven A | Medland, Sarah E | Miller, Kathryn A | Montgomery, Grant W | Morrison, Alanna C | Müller-Nurasyid, Martina | Navarro, Pau | Nelis, Mari | O’Connell, Jeffrey R | O’Donnell, Christopher J | Ong, Ken K | Newman, Anne B | Peters, Annette | Polasek, Ozren | Pouta, Anneli | Pramstaller, Peter P | Psaty, Bruce M | Rao, Dabeeru C | Ring, Susan M | Rossin, Elizabeth J | Rudan, Diana | Sanna, Serena | Scott, Robert A | Sehmi, Jaban S | Sharp, Stephen | Shin, Jordan T | Singleton, Andrew B | Smith, Albert V | Soranzo, Nicole | Spector, Tim D | Stewart, Chip | Stringham, Heather M | Tarasov, Kirill V | Uitterlinden, André G | Vandenput, Liesbeth | Hwang, Shih-Jen | Whitfield, John B | Wijmenga, Cisca | Wild, Sarah H | Willemsen, Gonneke | Wilson, James F | Witteman, Jacqueline C M | Wong, Andrew | Wong, Quenna | Jamshidi, Yalda | Zitting, Paavo | Boer, Jolanda M A | Boomsma, Dorret I | Borecki, Ingrid B | Van Duijn, Cornelia M | Ekelund, Ulf | Forouhi, Nita G | Froguel, Philippe | Hingorani, Aroon | Ingelsson, Erik | Kivimaki, Mika | Kronmal, Richard A | Kuh, Diana | Lind, Lars | Martin, Nicholas G | Oostra, Ben A | Pedersen, Nancy L | Quertermous, Thomas | Rotter, Jerome I | van der Schouw, Yvonne T | Verschuren, W M Monique | Walker, Mark | Albanes, Demetrius | Arnar, David O | Assimes, Themistocles L | Bandinelli, Stefania | Boehnke, Michael | de Boer, Rudolf A | Bouchard, Claude | Caulfield, W L Mark | Chambers, John C | Curhan, Gary | Cusi, Daniele | Eriksson, Johan | Ferrucci, Luigi | van Gilst, Wiek H | Glorioso, Nicola | de Graaf, Jacqueline | Groop, Leif | Gyllensten, Ulf | Hsueh, Wen-Chi | Hu, Frank B | Huikuri, Heikki V | Hunter, David J | Iribarren, Carlos | Isomaa, Bo | Jarvelin, Marjo-Riitta | Jula, Antti | Kähönen, Mika | Kiemeney, Lambertus A | van der Klauw, Melanie M | Kooner, Jaspal S | Kraft, Peter | Iacoviello, Licia | Lehtimäki, Terho | Lokki, Marja-Liisa L | Mitchell, Braxton D | Navis, Gerjan | Nieminen, Markku S | Ohlsson, Claes | Poulter, Neil R | Qi, Lu | Raitakari, Olli T | Rimm, Eric B | Rioux, John D | Rizzi, Federica | Rudan, Igor | Salomaa, Veikko | Sever, Peter S | Shields, Denis C | Shuldiner, Alan R | Sinisalo, Juha | Stanton, Alice V | Stolk, Ronald P | Strachan, David P | Tardif, Jean-Claude | Thorsteinsdottir, Unnur | Tuomilehto, Jaako | van Veldhuisen, Dirk J | Virtamo, Jarmo | Viikari, Jorma | Vollenweider, Peter | Waeber, Gérard | Widen, Elisabeth | Cho, Yoon Shin | Olsen, Jesper V | Visscher, Peter M | Willer, Cristen | Franke, Lude | Erdmann, Jeanette | Thompson, John R | Pfeufer, Arne | Sotoodehnia, Nona | Newton-Cheh, Christopher | Ellinor, Patrick T | Stricker, Bruno H Ch | Metspalu, Andres | Perola, Markus | Beckmann, Jacques S | Smith, George Davey | Stefansson, Kari | Wareham, Nicholas J | Munroe, Patricia B | Sibon, Ody C M | Milan, David J | Snieder, Harold | Samani, Nilesh J | Loos, Ruth J F
Nature genetics  2013;45(6):621-631.
Elevated resting heart rate is associated with greater risk of cardiovascular disease and mortality. In a 2-stage meta-analysis of genome-wide association studies in up to 181,171 individuals, we identified 14 new loci associated with heart rate and confirmed associations with all 7 previously established loci. Experimental downregulation of gene expression in Drosophila melanogaster and Danio rerio identified 20 genes at 11 loci that are relevant for heart rate regulation and highlight a role for genes involved in signal transmission, embryonic cardiac development and the pathophysiology of dilated cardiomyopathy, congenital heart failure and/or sudden cardiac death. In addition, genetic susceptibility to increased heart rate is associated with altered cardiac conduction and reduced risk of sick sinus syndrome, and both heart rate–increasing and heart rate–decreasing variants associate with risk of atrial fibrillation. Our findings provide fresh insights into the mechanisms regulating heart rate and identify new therapeutic targets.
doi:10.1038/ng.2610
PMCID: PMC3696959  PMID: 23583979
PLoS ONE  2014;9(5):e96805.
Common genetic variants 3′ of MC4R within two large linkage disequilibrium (LD) blocks spanning 288 kb have been associated with common and rare forms of obesity. This large association region has not been refined and the relevant DNA segments within the association region have not been identified. In this study, we investigated whether common variants in the MC4R gene region were associated with adiposity-related traits in a biracial population-based study. Single nucleotide polymorphisms (SNPs) in the MC4R region were genotyped with a custom array and a genome-wide array and associations between SNPs and five adiposity-related traits were determined using race-stratified linear regression. Previously reported associations between lower BMI and the minor alleles of rs2229616/Val103Ile and rs52820871/Ile251Leu were replicated in white female participants. Among white participants, rs11152221 in a proximal 3′ LD block (closer to MC4R) was significantly associated with multiple adiposity traits, but SNPs in a distal 3′ LD block (farther from MC4R) were not. In a case-control study of severe obesity, rs11152221 was significantly associated. The association results directed our follow-up studies to the proximal LD block downstream of MC4R. By considering nucleotide conservation, the significance of association, and proximity to the MC4R gene, we identified a candidate MC4R regulatory region. This candidate region was sequenced in 20 individuals from a study of severe obesity in an attempt to identify additional variants, and the candidate region was tested for enhancer activity using in vivo enhancer assays in zebrafish and mice. Novel variants were not identified by sequencing and the candidate region did not drive reporter gene expression in zebrafish or mice. The identification of a putative insulator in this region could help to explain the challenges faced in this study and others to link SNPs associated with adiposity to altered MC4R expression.
doi:10.1371/journal.pone.0096805
PMCID: PMC4018404  PMID: 24820477
Diabetes Care  2013;36(4):873-878.
OBJECTIVE
The Old Order Amish (OOA) is a conservative Christian sect of European origin living in Pennsylvania. Diabetes is rare in adult OOA despite a mean BMI rivaling that in the general U.S. non-Hispanic white population. The current study examines childhood factors that may contribute to the low prevalence of diabetes in the OOA by comparing OOA children aged 8–19 years with National Health and Nutrition Examination Survey (NHANES) data and children from Maryland’s Eastern Shore (ES), a nearby, non-Amish, rural community. We hypothesized that pediatric overweight is less common in OOA children, that physical activity (PA) and BMI are inversely correlated, and that OOA children are more physically active than ES children.
RESEARCH DESIGN AND METHODS
We obtained anthropometric data in 270 OOA children and 229 ES children (166 non-Hispanic white, 60 non-Hispanic black, 3 Hispanic). PA was measured by hip-worn accelerometers in all ES children and in 198 OOA children. Instrumentation in 43 OOA children was identical to ES children.
RESULTS
OOA children were approximately 3.3 times less likely than non-Hispanic white ES children and NHANES estimates to be overweight (BMI ≥85th percentile, Centers for Disease Control and Prevention). Time spent in moderate/vigorous PA (MVPA) was inversely correlated to BMI z-score (r = −0.24, P = 0.0006). PA levels did not differ by ethnicity within the ES group, but OOA children spent an additional 34 min/day in light activity (442 ± 56 vs. 408 ± 75, P = 0.005) and, impressively, an additional 53 min/day in MVPA (106 ± 54 vs. 53 ± 32, P < 0.0001) compared with ES children. In both groups, boys were more active than girls but OOA girls were easily more active than ES boys.
CONCLUSIONS
We confirmed all three hypotheses. Together with our previous data, the study implies that the OOA tend to gain their excess weight relatively late in life and that OOA children are very physically active, both of which may provide some long-term protection against diabetes.
doi:10.2337/dc12-0934
PMCID: PMC3609522  PMID: 23093661
Nature methods  2009;6(3):10.1038/nmeth.1301.
Determining the long-range haplotypes in a diploid individual is a major technical challenge. Here we report a method of molecular haplotyping by directly imaging multiple polymorphic sites on individual human DNA molecules simultaneously. We demonstrate the utility of this technology by accurately determining the haplotypes consisting of up to 16 single-nucleotide polymorphisms in genomic regions up to 50 kilobases.
doi:10.1038/nmeth.1301
PMCID: PMC3880790  PMID: 19198595
Background
Ethnic differences in cardiac arrhythmia incidence have been reported, with a particularly high incidence of sudden cardiac death (SCD) and low incidence of atrial fibrillation in individuals of African ancestry. We tested the hypotheses that African ancestry and common genetic variants are associated with prolonged duration of cardiac repolarization, a central pathophysiological determinant of arrhythmia, as measured by the electrocardiographic QT interval.
Methods and Results
First, individual estimates of African and European ancestry were inferred from genome-wide single nucleotide polymorphism (SNP) data in seven population-based cohorts of African Americans (n=12 097) and regressed on measured QT interval from electrocardiograms. Second, imputation was performed for 2.8 million SNPs and a genome-wide association (GWA) study of QT interval performed in ten cohorts (n=13 105). There was no evidence of association between genetic ancestry and QT interval (p=0.94). Genome-wide significant associations (p<2.5×10−8) were identified with SNPs at two loci, upstream of the genes NOS1AP (rs12143842, p=2×10−15) and ATP1B1 (rs1320976, p=2×10−10). The most significant SNP in NOS1AP was the same as the strongest SNP previously associated with QT interval in individuals of European ancestry. Low p-values (p<10−5) were observed for SNPs at several other loci previously identified in GWA studies in individuals of European ancestry, including KCNQ1, KCNH2, LITAF and PLN.
Conclusions
We observed no difference in duration of cardiac repolarization with global genetic indices of African ancestry. In addition, our GWA study extends the association of polymorphisms at several loci associated with repolarization in individuals of European ancestry to include African Americans.
doi:10.1161/CIRCGENETICS.112.962787
PMCID: PMC3568265  PMID: 23166209
electrocardiography; electrophysiology; genome-wide association studies; ion channels; repolarization
Background
The PR interval (PR) as measured by the resting, standard 12-lead electrocardiogram (ECG) reflects the duration of atrial/atrioventricular nodal depolarization. Substantial evidence exists for a genetic contribution to PR, including genome-wide association studies that have identified common genetic variants at nine loci influencing PR in populations of European and Asian descent. However, few studies have examined loci associated with PR in African Americans.
Methods and Results
We present results from the largest genome-wide association study to date of PR in 13,415 adults of African descent from ten cohorts. We tested for association between PR (ms) and approximately 2.8 million genotyped and imputed single nucleotide polymorphisms. Imputation was performed using HapMap 2 YRI and CEU panels. Study-specific results, adjusted for global ancestry and clinical correlates of PR, were meta-analyzed using the inverse variance method. Variation in genome-wide test statistic distributions was noted within studies (lambda range: 0.9–1.1), although not after genomic control correction was applied to the overall meta-analysis (lambda: 1.008). In addition to generalizing previously reported associations with MEIS1, SCN5A, ARHGAP24, CAV1, and TBX5 to African American populations at the genome-wide significance level (P<5.0×10−8), we also identified a novel locus: ITGA9, located in a region previously implicated in SCN5A expression. The 3p21 region harboring SCN5A also contained two additional independent secondary signals influencing PR (P<5.0×10−8).
Conclusions
This study demonstrates the ability to map novel loci in African Americans as well as the generalizability of loci associated with PR across populations of African, European and Asian descent.
doi:10.1161/CIRCGENETICS.112.963991
PMCID: PMC3560365  PMID: 23139255
electrocardiography; epidemiology; GWAS; single nucleotide polymorphism genetics; PR interval
Aging cell  2009;8(4):460-472.
Summary
The insulin/IGF1 signaling pathways affect lifespan in several model organisms, including worms, flies and mice. To investigate whether common genetic variation in this pathway influences lifespan in humans, we genotyped 291 common variants in 30 genes encoding proteins in the insulin/IGF1 signaling pathway in a cohort of elderly Caucasian women selected from the Study of Osteoporotic Fractures (SOF), including 293 long-lived cases (lifespan ≥ 92 years (y), mean ± standard deviation (SD) = 95.3 ± 2.2y) and 603 average-lifespan controls (lifespan ≤ 79y, mean=75.7 ± 2.6y). Variants were selected for genotyping using a haplotype tagging approach. We found a modest excess of variants nominally associated with longevity. We then replicated nominally significant variants in two additional Caucasian cohorts containing both males and females: the Cardiovascular Health Study (CHS) and Ashkenazi Jewish Centenarians (AJC). An intronic single nucleotide polymorphism (SNP) in AKT1, rs3803304, was significantly associated with lifespan in a meta-analysis across the three cohorts (odds ratio (OR)=0.78 (95% confidence interval (CI)=0.68-0.89), adjusted p=0.043); two intronic SNPs in FOXO3A demonstrated a significant lifespan association among women only (rs1935949, OR=1.35, 95% CI=1.15-1.57, adjusted p=0.0093). Conclusion: common variants in several insulin/IGF1 pathway genes are associated with human lifespan.
doi:10.1111/j.1474-9726.2009.00493.x
PMCID: PMC3652804  PMID: 19489743
IGF1; longevity; gene; SNP; AKT1; FOXO3A
Human Molecular Genetics  2013;22(11):2312-2324.
Chronic periodontitis (CP) is a common oral disease that confers substantial systemic inflammatory and microbial burden and is a major cause of tooth loss. Here, we present the results of a genome-wide association study of CP that was carried out in a cohort of 4504 European Americans (EA) participating in the Atherosclerosis Risk in Communities (ARIC) Study (mean age—62 years, moderate CP—43% and severe CP—17%). We detected no genome-wide significant association signals for CP; however, we found suggestive evidence of association (P < 5 × 10−6) for six loci, including NIN, NPY, WNT5A for severe CP and NCR2, EMR1, 10p15 for moderate CP. Three of these loci had concordant effect size and direction in an independent sample of 656 adult EA participants of the Health, Aging, and Body Composition (Health ABC) Study. Meta-analysis pooled estimates were severe CP (n = 958 versus health: n = 1909)—NPY, rs2521634 [G]: odds ratio [OR = 1.49 (95% confidence interval (CI = 1.28–1.73, P = 3.5 × 10−7))]; moderate CP (n = 2293)—NCR2, rs7762544 [G]: OR = 1.40 (95% CI = 1.24–1.59, P = 7.5 × 10−8), EMR1, rs3826782 [A]: OR = 2.01 (95% CI = 1.52–2.65, P = 8.2 × 10−7). Canonical pathway analysis indicated significant enrichment of nervous system signaling, cellular immune response and cytokine signaling pathways. A significant interaction of NUAK1 (rs11112872, interaction P = 2.9 × 10−9) with smoking in ARIC was not replicated in Health ABC, although estimates of heritable variance in severe CP explained by all single nucleotide polymorphisms increased from 18 to 52% with the inclusion of a genome-wide interaction term with smoking. These genome-wide association results provide information on multiple candidate regions and pathways for interrogation in future genetic studies of CP.
doi:10.1093/hmg/ddt065
PMCID: PMC3652417  PMID: 23459936
Lens transparency, or the magnitude of cataract severity, is a potential in vivo marker of aging distinguishable from diagnosed cataract. To explore lens transparency as a marker of aging, we determined its association with leukocyte telomere length (LTL) measured with quantitative polymerase chain reaction. Cataract severity was directly measured in 259 participants, and prevalent cataract and incident cataract surgery were ascertained in 2,750 participants of the Health, Aging, and Body Composition Study. LTL was unassociated with clinical cataract outcomes. Six of 259 had successfully aged lenses and a mean LTL of 5,700 bp, whereas 253/259 with poorly aged lenses had a mean LTL of 4,770 bp. Participants with a 1,000 bp greater mean LTL had nearly half the odds of any cataract (odds ratio = 0.47, 95% confidence interval 0.22–1.02) after adjustment. Lens transparency might be associated with longer LTL in community-dwelling older adults and should be investigated further as a possible biomarker of aging.
doi:10.1093/gerona/glr034
PMCID: PMC3110909  PMID: 21382885
Lens transparency; Cataract; Leukocyte telomere length; Aging; Biomarker
Ageing research reviews  2010;10(2):225-237.
The TOR (target of rapamycin) signal transduction network monitors intra- and extracellular conditions that favor cell growth. Research during the last decade has revealed a modular structure of the TOR signaling network. Each signaling module senses a particular set of signals from the cellular milieu and exerts regulatory control towards TOR activity. The TOR pathway responds to growth factor signals, nutrient availability, and cellular stresses like hypoxia and energy stress. The signaling modules and their molecular components constituting the TOR network are remarkably conserved in both sequence and function across species. In yeast, roundworms, flies, and mice, the TOR pathway has been shown to regulate lifespan. Correspondingly, genetic, dietary or pharmacological manipulation of individual signaling modules as well as TOR activity itself extends lifespan in these model organisms. We discuss the potential impact of manipulating TOR activity for human health and lifespan.
doi:10.1016/j.arr.2010.04.001
PMCID: PMC2943975  PMID: 20385253
Longevity; aging; ageing; lifespan; TOR; TORC1
Neurobiology of aging  2009;32(11):2055-2060.
Telomere shortening is a marker of cellular aging and has been associated with risk of Alzheimer’s disease. Few studies have determined if telomere length is associated with cognitive decline in non-demented elders. We prospectively studied 2,734 non-demented elders (mean age: 74 years). We measured cognition with the Modified Mini-Mental State Exam (3MS) and Digit Symbol Substitution Test (DSST) repeatedly over 7 years. Baseline telomere length was measured in blood leukocytes and classified by tertile as “short”, “medium”, or “long”. At baseline, longer telomere length was associated with better DSST score (36.4, 34.9 and 34.4 points for long, medium and short, p <0.01) but not for change in score. However, seven-year 3MS change scores were less among those with longer telomere length (−1.7 points vs. −2.5 and −2.9, p = 0.01). Findings were similar after multivariable adjustment for age, gender, race, education, assay batch, and baseline score. There was a borderline statistically significant interaction for telomere length and APOE e4 on 3MS change score (p=0.06). Thus, telomere length may serve as a biomarker for cognitive aging.
doi:10.1016/j.neurobiolaging.2009.12.006
PMCID: PMC2916948  PMID: 20031273
Cognitive Decline; Biomarker; Genetics; Telomeres; Epidemiology
PLoS ONE  2011;6(5):e19687.
Background
Leukocyte telomere length (LTL) is an emerging marker of biological age. Chronic inflammatory activity is commonly proposed as a promoter of biological aging in general, and of leukocyte telomere shortening in particular. In addition, senescent cells with critically short telomeres produce pro-inflammatory factors. However, in spite of the proposed causal links between inflammatory activity and LTL, there is little clinical evidence in support of their covariation and interaction.
Methodology/Principal Findings
To address this issue, we examined if individuals with high levels of the systemic inflammatory markers interleukin-6 (IL-6), tumor necrosis factor-α (TNF-α) and C-reactive protein (CRP) had increased odds for short LTL. Our sample included 1,962 high-functioning adults who participated in the Health, Aging and Body Composition Study (age range: 70–79 years). Logistic regression analyses indicated that individuals with high levels of either IL-6 or TNF-α had significantly higher odds for short LTL. Furthermore, individuals with high levels of both IL-6 and TNF-α had significantly higher odds for short LTL compared with those who had neither high (OR = 0.52, CI = 0.37–0.72), only IL-6 high (OR = 0.57, CI = 0.39–0.83) or only TNF-α high (OR = 0.67, CI = 0.46–0.99), adjusting for a wide variety of established risk factors and potential confounds. In contrast, CRP was not associated with LTL.
Conclusions/Significance
Results suggest that cumulative inflammatory load, as indexed by the combination of high levels of IL-6 and TNF-α, is associated with increased odds for short LTL. In contrast, high levels of CRP were not accompanied by short LTL in this cohort of older adults. These data provide the first large-scale demonstration of links between inflammatory markers and LTL in an older population.
doi:10.1371/journal.pone.0019687
PMCID: PMC3094351  PMID: 21602933
Journal of medical genetics  2009;47(1):1-7.
Peripheral arterial disease (PAD) is associated with significant morbidity and mortality, and has a higher prevalence in African Americans than Caucasians. Ankle arm index (AAI) is the ratio of systolic blood pressure in the leg to that in the arm, and, when low, is a marker of PAD. We used an admixture mapping approach to search for genetic loci associated with low AAI. Using data from 1040 African-American participants in the observational, population-based Health, Aging, and Body Composition Study who were genotyped at 1322 single nucleotide polymorphisms(SNPs) that are informative for African versus European ancestry and span the entire genome, we estimated genetic ancestry in each chromosomal region and then tested the association between AAI and genetic ancestry at each locus. We found a region of chromosome 11 that reaches its peak between 80 and 82 Mb associated with low AAI (p<0.001 for rs12289502 and rs9665943, both within this region). 753 African-American participants in the observational, population-based Cardiovascular Health Study were genotyped at rs9665943 to test the reproducibility of this association, and this association was also statistically significant (odds ratio(OR) for homozygous African genotype 1.59 (95% confidence interval (CI) 1.12–2.27)). Another candidate SNP (rs1042602) in the same genomic region was tested in both populations, and was also found to be significantly associated with low AAI in both populations (OR for homozygous African genotype 1.89 (95% CI 1.29–2.76)). This study identifies a novel region of chromosome 11 representing an area with a potential candidate gene associated with PAD in African Americans.
doi:10.1136/jmg.2008.064808
PMCID: PMC2805758  PMID: 19586928
peripheral vascular disease; genetics; African-American
OBJECTIVE
To evaluate the relationship between serum insulin-like growth factor 1 (IGF-1), IGF-1 binding protein 1 (IGFBP-1), and IGF-1 binding protein 2 (IGFBP-2) and fasting insulin, fasting glucose, adiposity, and mortality in older adults.
DESIGN
A prospective cohort study with mean follow-up of 6.2 years.
SETTING
Participants were recruited and followed at two centers affiliated with academic medical institutions.
PARTICIPANTS
Six hundred twenty-five men and women aged 70 and older and in good health at the time of enrollment.
MEASUREMENTS
Serum IGF-1, IGFBP-1, and IGFBP-2; fasting serum insulin; fasting serum glucose; visceral fat; and total percent fat.
RESULTS
Higher IGFBP-1 and higher IGFBP-2 were significantly associated with lower fasting insulin, lower fasting glucose, and lower adiposity, but higher IGFBP-1 and IGFBP-2 were associated with greater mortality. In multivariate adjusted models, the hazard ratio for all-cause mortality was 1.48 (95% confidence interval (CI)=1.14–1.92) per standard deviation (SD) increase in IGFBP-2 and 1.34 (95% CI = 1.01–1.76) per SD increase in IGFBP-1. No association was found between IGF-1 and all-cause mortality.
CONCLUSIONS
Higher IGFBP-1 and IGFBP-2 are associated with lower adiposity and decreased glucose tolearance but also with greater all-cause mortality. Higher levels of serum IGF-1 binding protein (IGFBP) may indicate greater IGF-1 activity and thus represent an association between higher IGF-1 activity and mortality in humans.
doi:10.1111/j.1532-5415.2009.02318.x
PMCID: PMC2771612  PMID: 19558480
aging; IGF-1; IGFBP; mortality
PLoS Genetics  2009;5(5):e1000490.
The prevalence of obesity (body mass index (BMI) ≥30 kg/m2) is higher in African Americans than in European Americans, even after adjustment for socioeconomic factors, suggesting that genetic factors may explain some of the difference. To identify genetic loci influencing BMI, we carried out a pooled analysis of genome-wide admixture mapping scans in 15,280 African Americans from 14 epidemiologic studies. Samples were genotyped at a median of 1,411 ancestry-informative markers. After adjusting for age, sex, and study, BMI was analyzed both as a dichotomized (top 20% versus bottom 20%) and a continuous trait. We found that a higher percentage of European ancestry was significantly correlated with lower BMI (ρ = −0.042, P = 1.6×10−7). In the dichotomized analysis, we detected two loci on chromosome X as associated with increased African ancestry: the first at Xq25 (locus-specific LOD = 5.94; genome-wide score = 3.22; case-control Z = −3.94); and the second at Xq13.1 (locus-specific LOD = 2.22; case-control Z = −4.62). Quantitative analysis identified a third locus at 5q13.3 where higher BMI was highly significantly associated with greater European ancestry (locus-specific LOD = 6.27; genome-wide score = 3.46). Further mapping studies with dense sets of markers will be necessary to identify the alleles in these regions of chromosomes X and 5 that may be associated with variation in BMI.
Author Summary
Obesity is about 1.5-fold more prevalent in African Americans than European Americans. To determine whether genetic background may contribute to this observed disparity, we scanned the genomes of African Americans, searching for genomic regions where obese individuals have a difference from the average proportion of African ancestry. By examining genetic data from more than 15,000 African Americans, we show that the proportion of European ancestry is inversely correlated with BMI. In obese individuals, we detect two loci with increased African ancestry on chromosome X (Xq13.1 and Xq25) and one locus with increased European ancestry on chromosome 5 (5q13.3). The 5q13.3 and Xq25 regions both contain genes that are known to be involved in appetite regulation. Our results suggest that genetic factors may contribute to the difference in obesity prevalence between African Americans and European Americans. Further studies of the regions may identify the causative variants affecting susceptibility to obesity.
doi:10.1371/journal.pgen.1000490
PMCID: PMC2679192  PMID: 19461885
PLoS Genetics  2009;5(1):e1000360.
Persistently low white blood cell count (WBC) and neutrophil count is a well-described phenomenon in persons of African ancestry, whose etiology remains unknown. We recently used admixture mapping to identify an approximately 1-megabase region on chromosome 1, where ancestry status (African or European) almost entirely accounted for the difference in WBC between African Americans and European Americans. To identify the specific genetic change responsible for this association, we analyzed genotype and phenotype data from 6,005 African Americans from the Jackson Heart Study (JHS), the Health, Aging and Body Composition (Health ABC) Study, and the Atherosclerosis Risk in Communities (ARIC) Study. We demonstrate that the causal variant must be at least 91% different in frequency between West Africans and European Americans. An excellent candidate is the Duffy Null polymorphism (SNP rs2814778 at chromosome 1q23.2), which is the only polymorphism in the region known to be so differentiated in frequency and is already known to protect against Plasmodium vivax malaria. We confirm that rs2814778 is predictive of WBC and neutrophil count in African Americans above beyond the previously described admixture association (P = 3.8×10−5), establishing a novel phenotype for this genetic variant.
Author Summary
Many African Americans have white blood cell counts (WBC) that are persistently below the normal range for people of European descent, a condition called “benign ethnic neutropenia.” Because most African Americans have both African and European ancestors, selected genetic variants can be analyzed to assign probable African or European origin to each region of each such person's chromosomes. Previously, we found a region on chromosome 1 where increased local African ancestry completely accounted for differences in WBC between African and European Americans, suggesting the presence of an African-derived variant causing low WBC. Here, we show that low neutrophil count is predominantly responsible for low WBC; that a dominant, European-derived allele contributes to high neutrophil count; and that the frequency of this allele differs in Africans and Europeans by >91%. Across the chromosome 1 locus, only the well-characterized “Duffy” polymorphism was this differentiated. Neutrophil count was more strongly associated to the Duffy variant than to ancestry, suggesting that the variant itself causes benign ethnic neutropenia. The African, or “null,” form of this variant abolishes expression of the “Duffy Antigen Receptor for Chemokines” on red blood cells, perhaps altering the concentrations and distribution of chemokines that regulate neutrophil production or migration.
doi:10.1371/journal.pgen.1000360
PMCID: PMC2628742  PMID: 19180233
Age  2006;28(4):313-332.
Centenarians represent a rare phenotype appearing in roughly 10–20 per 100,000 persons in most industrialized countries but as high as 40–50 per 100,000 persons in Okinawa, Japan. Siblings of centenarians in Okinawa have been found to have cumulative survival advantages such that female centenarian siblings have a 2.58-fold likelihood and male siblings a 5.43-fold likelihood (versus their birth cohorts) of reaching the age of 90 years. This is indicative of a strong familial component to longevity. Centenarians may live such extraordinarily long lives in large part due to genetic variations that either affect the rate of aging and/or have genes that result in decreased susceptibility to age-associated diseases. Some of the most promising candidate genes appear to be those involved in regulatory pathways such as insulin signaling, immunoinflammatory response, stress resistance or cardiovascular function. Although gene variants with large beneficial effects have been suggested to exist, only APOE, an important regulator of lipoproteins has been consistently associated with a longer human lifespan across numerous populations. As longevity is a very complex trait, several issues challenge our ability to identify its genetic influences, such as control for environmental confounders across time, the lack of precise phenotypes of aging and longevity, statistical power, study design and availability of appropriate study populations. Genetic studies on the Okinawan population suggest that Okinawans are a genetically distinct group that has several characteristics of a founder population, including less genetic diversity, and clustering of specific gene variants, some of which may be related to longevity. Further work on this population and other genetic isolates would be of significant interest to the genetics of human longevity.
doi:10.1007/s11357-006-9020-x
PMCID: PMC3259160  PMID: 22253498
longevity; genetics; centenarians; Okinawa; longevity genes
PLoS Biology  2005;3(9):e315.
The demonstration of association between common genetic variants and chronic human diseases such as obesity could have profound implications for the prediction, prevention, and treatment of these conditions. Unequivocal proof of such an association, however, requires independent replication of initial positive findings. Recently, three (−243 A>G, +61450 C>A, and +83897 T>A) single nucleotide polymorphisms (SNPs) within glutamate decarboxylase 2 (GAD2) were found to be associated with class III obesity (body mass index > 40 kg/m2). The association was observed among 188 families (612 individuals) segregating the condition, and a case-control study of 575 cases and 646 lean controls. Functional data supporting a pathophysiological role for one of the SNPs (−243 A>G) were also presented. The gene GAD2 encodes the 65-kDa subunit of glutamic acid decarboxylase—GAD65. In the present study, we attempted to replicate this association in larger groups of individuals, and to extend the functional studies of the −243 A>G SNP. Among 2,359 individuals comprising 693 German nuclear families with severe, early-onset obesity, we found no evidence for a relationship between the three GAD2 SNPs and obesity, whether SNPs were studied individually or as haplotypes. In two independent case-control studies (a total of 680 class III obesity cases and 1,186 lean controls), there was no significant relationship between the −243 A>G SNP and obesity (OR = 0.99, 95% CI 0.83–1.18, p = 0.89) in the pooled sample. These negative findings were recapitulated in a meta-analysis, incorporating all published data for the association between the −243G allele and class III obesity, which yielded an OR of 1.11 (95% CI 0.90–1.36, p = 0.28) in a total sample of 1,252 class III obese cases and 1,800 lean controls. Moreover, analysis of common haplotypes encompassing the GAD2 locus revealed no association with severe obesity in families with the condition. We also obtained functional data for the −243 A>G SNP that does not support a pathophysiological role for this variant in obesity. Potential confounding variables in association studies involving common variants and complex diseases (low power to detect modest genetic effects, overinterpretation of marginal data, population stratification, and biological plausibility) are also discussed in the context of GAD2 and severe obesity.
A large genetic study involving multiple populations is not able to replicate previous findings linking variation in the GAD2 gene to susceptibility to obesity.
doi:10.1371/journal.pbio.0030315
PMCID: PMC1193520  PMID: 16122350

Results 1-25 (25)