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Leong, Aaron

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Leong, Aaron
Author's Publications: search.filters.isAuthorOfPublication.8e1a4340-0230-4244-b7f6-0fce2fda620c

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Now showing 1 - 8 of 8
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    Low-frequency and rare exome chip variants associate with fasting glucose and type 2 diabetes susceptibility
    (Nature Pub. Group, 2015) Wessel, Jennifer; Chu, Audrey Y; Willems, Sara M; Wang, Shuai; Yaghootkar, Hanieh; Brody, Jennifer A; Dauriz, Marco; Hivert, Marie-France; Raghavan, Sridharan; Lipovich, Leonard; Hidalgo, Bertha; Fox, Keolu; Huffman, Jennifer E; An, Ping; Lu, Yingchang; Rasmussen-Torvik, Laura J; Grarup, Niels; Ehm, Margaret G; Li, Li; Baldridge, Abigail S; Stančáková, Alena; Abrol, Ravinder; Besse, Céline; Boland, Anne; Bork-Jensen, Jette; Fornage, Myriam; Freitag, Daniel F; Garcia, Melissa E; Guo, Xiuqing; Hara, Kazuo; Isaacs, Aaron; Jakobsdottir, Johanna; Lange, Leslie A; Layton, Jill C; Li, Man; Hua Zhao, Jing; Meidtner, Karina; Morrison, Alanna C; Nalls, Mike A; Peters, Marjolein J; Sabater-Lleal, Maria; Schurmann, Claudia; Silveira, Angela; Smith, Albert V; Southam, Lorraine; Stoiber, Marcus H; Strawbridge, Rona J; Taylor, Kent D; Varga, Tibor V; Allin, Kristine H; Amin, Najaf; Aponte, Jennifer L; Aung, Tin; Barbieri, Caterina; Bihlmeyer, Nathan A; Boehnke, Michael; Bombieri, Cristina; Bowden, Donald W; Burns, Sean; Chen, Yuning; Chen, Yii-DerI; Cheng, Ching-Yu; Correa, Adolfo; Czajkowski, Jacek; Dehghan, Abbas; Ehret, Georg B; Eiriksdottir, Gudny; Escher, Stefan A; Farmaki, Aliki-Eleni; Frånberg, Mattias; Gambaro, Giovanni; Giulianini, Franco; Goddard, William A; Goel, Anuj; Gottesman, Omri; Grove, Megan L; Gustafsson, Stefan; Hai, Yang; Hallmans, Göran; Heo, Jiyoung; Hoffmann, Per; Ikram, Mohammad K; Jensen, Richard A; Jørgensen, Marit E; Jørgensen, Torben; Karaleftheri, Maria; Khor, Chiea C; Kirkpatrick, Andrea; Kraja, Aldi T; Kuusisto, Johanna; Lange, Ethan M; Lee, I T; Lee, Wen-Jane; Leong, Aaron; Liao, Jiemin; Liu, Chunyu; Liu, Yongmei; Lindgren, Cecilia M; Linneberg, Allan; Malerba, Giovanni; Mamakou, Vasiliki; Marouli, Eirini; Maruthur, Nisa M; Matchan, Angela; McKean-Cowdin, Roberta; McLeod, Olga; Metcalf, Ginger A; Mohlke, Karen L; Muzny, Donna M; Ntalla, Ioanna; Palmer, Nicholette D; Pasko, Dorota; Peter, Andreas; Rayner, Nigel W; Renström, Frida; Rice, Ken; Sala, Cinzia F; Sennblad, Bengt; Serafetinidis, Ioannis; Smith, Jennifer A; Soranzo, Nicole; Speliotes, Elizabeth K; Stahl, Eli A; Stirrups, Kathleen; Tentolouris, Nikos; Thanopoulou, Anastasia; Torres, Mina; Traglia, Michela; Tsafantakis, Emmanouil; Javad, Sundas; Yanek, Lisa R; Zengini, Eleni; Becker, Diane M; Bis, Joshua C; Brown, James B; Adrienne Cupples, L; Hansen, Torben; Ingelsson, Erik; Karter, Andrew J; Lorenzo, Carlos; Mathias, Rasika A; Norris, Jill M; Peloso, Gina M; Sheu, Wayne H.-H.; Toniolo, Daniela; Vaidya, Dhananjay; Varma, Rohit; Wagenknecht, Lynne E; Boeing, Heiner; Bottinger, Erwin P; Dedoussis, George; Deloukas, Panos; Ferrannini, Ele; Franco, Oscar H; Franks, Paul W; Gibbs, Richard A; Gudnason, Vilmundur; Hamsten, Anders; Harris, Tamara B; Hattersley, Andrew T; Hayward, Caroline; Hofman, Albert; Jansson, Jan-Håkan; Langenberg, Claudia; Launer, Lenore J; Levy, Daniel; Oostra, Ben A; O'Donnell, Christopher; O'Rahilly, Stephen; Padmanabhan, Sandosh; Pankow, James S; Polasek, Ozren; Province, Michael A; Rich, Stephen S; Ridker, Paul; Rudan, Igor; Schulze, Matthias B; Smith, Blair H; Uitterlinden, André G; Walker, Mark; Watkins, Hugh; Wong, Tien Y; Zeggini, Eleftheria; Sharp, Stephen J; Forouhi, Nita G; Kerrison, Nicola D; Lucarelli, Debora ME; Sims, Matt; Barroso, Inês; McCarthy, Mark I; Arriola, Larraitz; Balkau, Beverley; Barricarte, Aurelio; Gonzalez, Carlos; Grioni, Sara; Kaaks, Rudolf; Key, Timothy J; Navarro, Carmen; Nilsson, Peter M; Overvad, Kim; Palli, Domenico; Panico, Salvatore; Quirós, J. Ramón; Rolandsson, Olov; Sacerdote, Carlotta; Sánchez, María–José; Slimani, Nadia; Tjonneland, Anne; Tumino, Rosario; van der A, Daphne L; van der Schouw, Yvonne T; Riboli, Elio; Laakso, Markku; Borecki, Ingrid B; Chasman, Daniel; Pedersen, Oluf; Psaty, Bruce M; Shyong Tai, E; van Duijn, Cornelia M; Wareham, Nicholas J; Waterworth, Dawn M; Boerwinkle, Eric; Linda Kao, W H; Florez, Jose; Loos, Ruth J.F.; Wilson, James G; Frayling, Timothy M; Siscovick, David S; Dupuis, Josée; Rotter, Jerome I; Meigs, James; Scott, Robert A; Goodarzi, Mark O
    Fasting glucose and insulin are intermediate traits for type 2 diabetes. Here we explore the role of coding variation on these traits by analysis of variants on the HumanExome BeadChip in 60,564 non-diabetic individuals and in 16,491 T2D cases and 81,877 controls. We identify a novel association of a low-frequency nonsynonymous SNV in GLP1R (A316T; rs10305492; MAF=1.4%) with lower FG (β=−0.09±0.01 mmol l−1, P=3.4 × 10−12), T2D risk (OR[95%CI]=0.86[0.76–0.96], P=0.010), early insulin secretion (β=−0.07±0.035 pmolinsulin mmolglucose−1, P=0.048), but higher 2-h glucose (β=0.16±0.05 mmol l−1, P=4.3 × 10−4). We identify a gene-based association with FG at G6PC2 (pSKAT=6.8 × 10−6) driven by four rare protein-coding SNVs (H177Y, Y207S, R283X and S324P). We identify rs651007 (MAF=20%) in the first intron of ABO at the putative promoter of an antisense lncRNA, associating with higher FG (β=0.02±0.004 mmol l−1, P=1.3 × 10−8). Our approach identifies novel coding variant associations and extends the allelic spectrum of variation underlying diabetes-related quantitative traits and T2D susceptibility.
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    Vitamin D and Risk of Multiple Sclerosis: A Mendelian Randomization Study
    (Public Library of Science, 2015) Mokry, Lauren E.; Ross, Stephanie; Ahmad, Omar S.; Forgetta, Vincenzo; Smith, George Davey; Leong, Aaron; Greenwood, Celia M. T.; Thanassoulis, George; Richards, J. Brent
    Background: Observational studies have demonstrated an association between decreased vitamin D level and risk of multiple sclerosis (MS); however, it remains unclear whether this relationship is causal. We undertook a Mendelian randomization (MR) study to evaluate whether genetically lowered vitamin D level influences the risk of MS. Methods and Findings: We identified single nucleotide polymorphisms (SNPs) associated with 25-hydroxyvitamin D (25OHD) level from SUNLIGHT, the largest (n = 33,996) genome-wide association study to date for vitamin D. Four SNPs were genome-wide significant for 25OHD level (p-values ranging from 6 × 10−10 to 2 × 10−109), and all four SNPs lay in, or near, genes strongly implicated in separate mechanisms influencing 25OHD. We then ascertained their effect on 25OHD level in 2,347 participants from a population-based cohort, the Canadian Multicentre Osteoporosis Study, and tested the extent to which the 25OHD-decreasing alleles explained variation in 25OHD level. We found that the count of 25OHD-decreasing alleles across these four SNPs was strongly associated with lower 25OHD level (n = 2,347, F-test statistic = 49.7, p = 2.4 × 10−12). Next, we conducted an MR study to describe the effect of genetically lowered 25OHD on the odds of MS in the International Multiple Sclerosis Genetics Consortium study, the largest genetic association study to date for MS (including up to 14,498 cases and 24,091 healthy controls). Alleles were weighted by their relative effect on 25OHD level, and sensitivity analyses were performed to test MR assumptions. MR analyses found that each genetically determined one-standard-deviation decrease in log-transformed 25OHD level conferred a 2.0-fold increase in the odds of MS (95% CI: 1.7–2.5; p = 7.7 × 10−12; I2 = 63%, 95% CI: 0%–88%). This result persisted in sensitivity analyses excluding SNPs possibly influenced by population stratification or pleiotropy (odds ratio [OR] = 1.7, 95% CI: 1.3–2.2; p = 2.3 × 10−5; I2 = 47%, 95% CI: 0%–85%) and including only SNPs involved in 25OHD synthesis or metabolism (ORsynthesis = 2.1, 95% CI: 1.6–2.6, p = 1 × 10−9; ORmetabolism = 1.9, 95% CI: 1.3–2.7, p = 0.002). While these sensitivity analyses decreased the possibility that pleiotropy may have biased the results, residual pleiotropy is difficult to exclude entirely. Conclusions: A genetically lowered 25OHD level is strongly associated with increased susceptibility to MS. Whether vitamin D sufficiency can delay, or prevent, MS onset merits further investigation in long-term randomized controlled trials.
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    Re-analysis of public genetic data reveals a rare X-chromosomal variant associated with type 2 diabetes
    (Nature Publishing Group UK, 2018) Bonàs-Guarch, Sílvia; Guindo-Martínez, Marta; Miguel-Escalada, Irene; Grarup, Niels; Sebastian, David; Rodriguez-Fos, Elias; Sánchez, Friman; Planas-Fèlix, Mercè; Cortes-Sánchez, Paula; González, Santi; Timshel, Pascal; Pers, Tune H.; Morgan, Claire C.; Moran, Ignasi; Atla, Goutham; González, Juan R.; Puiggros, Montserrat; Martí, Jonathan; Andersson, Ehm A.; Díaz, Carlos; Badia, Rosa M.; Udler, Miriam; Leong, Aaron; Kaur, Varindepal; Flannick, Jason; Jørgensen, Torben; Linneberg, Allan; Jørgensen, Marit E.; Witte, Daniel R.; Christensen, Cramer; Brandslund, Ivan; Appel, Emil V.; Scott, Robert A.; Luan, Jian’an; Langenberg, Claudia; Wareham, Nicholas J.; Pedersen, Oluf; Zorzano, Antonio; Florez, Jose; Hansen, Torben; Ferrer, Jorge; Mercader, Josep Maria; Torrents, David
    The reanalysis of existing GWAS data represents a powerful and cost-effective opportunity to gain insights into the genetics of complex diseases. By reanalyzing publicly available type 2 diabetes (T2D) genome-wide association studies (GWAS) data for 70,127 subjects, we identify seven novel associated regions, five driven by common variants (LYPLAL1, NEUROG3, CAMKK2, ABO, and GIP genes), one by a low-frequency (EHMT2), and one driven by a rare variant in chromosome Xq23, rs146662057, associated with a twofold increased risk for T2D in males. rs146662057 is located within an active enhancer associated with the expression of Angiotensin II Receptor type 2 gene (AGTR2), a modulator of insulin sensitivity, and exhibits allelic specific activity in muscle cells. Beyond providing insights into the genetics and pathophysiology of T2D, these results also underscore the value of reanalyzing publicly available data using novel genetic resources and analytical approaches.
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    Publisher Correction: Re-analysis of public genetic data reveals a rare X-chromosomal variant associated with type 2 diabetes
    (Nature Publishing Group UK, 2018) Bonàs-Guarch, Sílvia; Guindo-Martínez, Marta; Miguel-Escalada, Irene; Grarup, Niels; Sebastian, David; Rodriguez-Fos, Elias; Sánchez, Friman; Planas-Fèlix, Mercè; Cortes-Sánchez, Paula; González, Santi; Timshel, Pascal; Pers, Tune H.; Morgan, Claire C.; Moran, Ignasi; Atla, Goutham; González, Juan R.; Puiggros, Montserrat; Martí, Jonathan; Andersson, Ehm A.; Díaz, Carlos; Badia, Rosa M.; Udler, Miriam; Leong, Aaron; Kaur, Varindepal; Flannick, Jason; Jørgensen, Torben; Linneberg, Allan; Jørgensen, Marit E.; Witte, Daniel R.; Christensen, Cramer; Brandslund, Ivan; Appel, Emil V.; Scott, Robert A.; Luan, Jian’an; Langenberg, Claudia; Wareham, Nicholas J.; Pedersen, Oluf; Zorzano, Antonio; Florez, Jose; Hansen, Torben; Ferrer, Jorge; Mercader, Josep Maria; Torrents, David
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    Genome-Wide Association Study of the Modified Stumvoll Insulin Sensitivity Index Identifies BCL2 and FAM19A2 as Novel Insulin Sensitivity Loci
    (American Diabetes Association, 2016) Walford, Geoffrey A.; Gustafsson, Stefan; Rybin, Denis; Stančáková, Alena; Chen, Han; Liu, Ching-Ti; Hong, Jaeyoung; Jensen, Richard A.; Rice, Ken; Morris, Andrew P.; Mägi, Reedik; Tönjes, Anke; Prokopenko, Inga; Kleber, Marcus E.; Delgado, Graciela; Silbernagel, Günther; Jackson, Anne U.; Appel, Emil V.; Grarup, Niels; Lewis, Joshua P.; Montasser, May E.; Landenvall, Claes; Staiger, Harald; Luan, Jian’an; Frayling, Timothy M.; Weedon, Michael N.; Xie, Weijia; Morcillo, Sonsoles; Martínez-Larrad, María Teresa; Biggs, Mary L.; Chen, Yii-Der Ida; Corbaton-Anchuelo, Arturo; Færch, Kristine; Gómez-Zumaquero, Juan Miguel; Goodarzi, Mark O.; Kizer, Jorge R.; Koistinen, Heikki A.; Leong, Aaron; Lind, Lars; Lindgren, Cecilia; Machicao, Fausto; Manning, Alisa; Martín-Núñez, Gracia María; Rojo-Martínez, Gemma; Rotter, Jerome I.; Siscovick, David S.; Zmuda, Joseph M.; Zhang, Zhongyang; Serrano-Rios, Manuel; Smith, Ulf; Soriguer, Federico; Hansen, Torben; Jørgensen, Torben J.; Linnenberg, Allan; Pedersen, Oluf; Walker, Mark; Langenberg, Claudia; Scott, Robert A.; Wareham, Nicholas J.; Fritsche, Andreas; Häring, Hans-Ulrich; Stefan, Norbert; Groop, Leif; O’Connell, Jeff R.; Boehnke, Michael; Bergman, Richard N.; Collins, Francis S.; Mohlke, Karen L.; Tuomilehto, Jaakko; März, Winfried; Kovacs, Peter; Stumvoll, Michael; Psaty, Bruce M.; Kuusisto, Johanna; Laakso, Markku; Meigs, James; Dupuis, Josée; Ingelsson, Erik; Florez, Jose
    Genome-wide association studies (GWAS) have found few common variants that influence fasting measures of insulin sensitivity. We hypothesized that a GWAS of an integrated assessment of fasting and dynamic measures of insulin sensitivity would detect novel common variants. We performed a GWAS of the modified Stumvoll Insulin Sensitivity Index (ISI) within the Meta-Analyses of Glucose and Insulin-Related Traits Consortium. Discovery for genetic association was performed in 16,753 individuals, and replication was attempted for the 23 most significant novel loci in 13,354 independent individuals. Association with ISI was tested in models adjusted for age, sex, and BMI and in a model analyzing the combined influence of the genotype effect adjusted for BMI and the interaction effect between the genotype and BMI on ISI (model 3). In model 3, three variants reached genome-wide significance: rs13422522 (NYAP2; P = 8.87 × 10−11), rs12454712 (BCL2; P = 2.7 × 10−8), and rs10506418 (FAM19A2; P = 1.9 × 10−8). The association at NYAP2 was eliminated by conditioning on the known IRS1 insulin sensitivity locus; the BCL2 and FAM19A2 associations were independent of known cardiometabolic loci. In conclusion, we identified two novel loci and replicated known variants associated with insulin sensitivity. Further studies are needed to clarify the causal variant and function at the BCL2 and FAM19A2 loci.
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    Impact of common genetic determinants of Hemoglobin A1c on type 2 diabetes risk and diagnosis in ancestrally diverse populations: A transethnic genome-wide meta-analysis
    (Public Library of Science, 2017) Wheeler, Eleanor; Leong, Aaron; Liu, Ching-Ti; Hivert, Marie-France; Strawbridge, Rona J.; Podmore, Clara; Li, Man; Yao, Jie; Sim, Xueling; Hong, Jaeyoung; Chu, Audrey Y.; Zhang, Weihua; Wang, Xu; Chen, Peng; Maruthur, Nisa M.; Porneala, Bianca C.; Sharp, Stephen J.; Jia, Yucheng; Kabagambe, Edmond K.; Chang, Li-Ching; Chen, Wei-Min; Elks, Cathy E.; Evans, Daniel S.; Fan, Qiao; Giulianini, Franco; Go, Min Jin; Hottenga, Jouke-Jan; Hu, Yao; Jackson, Anne U.; Kanoni, Stavroula; Kim, Young Jin; Kleber, Marcus E.; Ladenvall, Claes; Lecoeur, Cecile; Lim, Sing-Hui; Lu, Yingchang; Mahajan, Anubha; Marzi, Carola; Nalls, Mike A.; Navarro, Pau; Nolte, Ilja M.; Rose, Lynda M.; Rybin, Denis V.; Sanna, Serena; Shi, Yuan; Stram, Daniel O.; Takeuchi, Fumihiko; Tan, Shu Pei; van der Most, Peter J.; Van Vliet-Ostaptchouk, Jana V.; Wong, Andrew; Yengo, Loic; Zhao, Wanting; Goel, Anuj; Martinez Larrad, Maria Teresa; Radke, Dörte; Salo, Perttu; Tanaka, Toshiko; van Iperen, Erik P. A.; Abecasis, Goncalo; Afaq, Saima; Alizadeh, Behrooz Z.; Bertoni, Alain G.; Bonnefond, Amelie; Böttcher, Yvonne; Bottinger, Erwin P.; Campbell, Harry; Carlson, Olga D.; Chen, Chien-Hsiun; Cho, Yoon Shin; Garvey, W. Timothy; Gieger, Christian; Goodarzi, Mark O.; Grallert, Harald; Hamsten, Anders; Hartman, Catharina A.; Herder, Christian; Hsiung, Chao Agnes; Huang, Jie; Igase, Michiya; Isono, Masato; Katsuya, Tomohiro; Khor, Chiea-Chuen; Kiess, Wieland; Kohara, Katsuhiko; Kovacs, Peter; Lee, Juyoung; Lee, Wen-Jane; Lehne, Benjamin; Li, Huaixing; Liu, Jianjun; Lobbens, Stephane; Luan, Jian'an; Lyssenko, Valeriya; Meitinger, Thomas; Miki, Tetsuro; Miljkovic, Iva; Moon, Sanghoon; Mulas, Antonella; Müller, Gabriele; Müller-Nurasyid, Martina; Nagaraja, Ramaiah; Nauck, Matthias; Pankow, James S.; Polasek, Ozren; Prokopenko, Inga; Ramos, Paula S.; Rasmussen-Torvik, Laura; Rathmann, Wolfgang; Rich, Stephen S.; Robertson, Neil R.; Roden, Michael; Roussel, Ronan; Rudan, Igor; Scott, Robert A.; Scott, William R.; Sennblad, Bengt; Siscovick, David S.; Strauch, Konstantin; Sun, Liang; Swertz, Morris; Tajuddin, Salman M.; Taylor, Kent D.; Teo, Yik-Ying; Tham, Yih Chung; Tönjes, Anke; Wareham, Nicholas J.; Willemsen, Gonneke; Wilsgaard, Tom; Hingorani, Aroon D.; Egan, Josephine; Ferrucci, Luigi; Hovingh, G. Kees; Jula, Antti; Kivimaki, Mika; Kumari, Meena; Njølstad, Inger; Palmer, Colin N. A.; Serrano Ríos, Manuel; Stumvoll, Michael; Watkins, Hugh; Aung, Tin; Blüher, Matthias; Boehnke, Michael; Boomsma, Dorret I.; Bornstein, Stefan R.; Chambers, John C.; Chasman, Daniel; Chen, Yii-Der Ida; Chen, Yduan-Tsong; Cheng, Ching-Yu; Cucca, Francesco; de Geus, Eco J. C.; Deloukas, Panos; Evans, Michele K.; Fornage, Myriam; Friedlander, Yechiel; Froguel, Philippe; Groop, Leif; Gross, Myron D.; Harris, Tamara B.; Hayward, Caroline; Heng, Chew-Kiat; Ingelsson, Erik; Kato, Norihiro; Kim, Bong-Jo; Koh, Woon-Puay; Kooner, Jaspal S.; Körner, Antje; Kuh, Diana; Kuusisto, Johanna; Laakso, Markku; Lin, Xu; Liu, Yongmei; Loos, Ruth J. F.; Magnusson, Patrik K. E.; März, Winfried; McCarthy, Mark I.; Oldehinkel, Albertine J.; Ong, Ken K.; Pedersen, Nancy L.; Pereira, Mark A.; Peters, Annette; Ridker, Paul; Sabanayagam, Charumathi; Sale, Michele; Saleheen, Danish; Saltevo, Juha; Schwarz, Peter EH.; Sheu, Wayne H. H.; Snieder, Harold; Spector, Timothy D.; Tabara, Yasuharu; Tuomilehto, Jaakko; van Dam, Rob M.; Wilson, James G.; Wilson, James F.; Wolffenbuttel, Bruce H. R.; Wong, Tien Yin; Wu, Jer-Yuarn; Yuan, Jian-Min; Zonderman, Alan B.; Soranzo, Nicole; Guo, Xiuqing; Roberts, David J.; Florez, Jose; Sladek, Robert; Dupuis, Josée; Morris, Andrew P.; Tai, E-Shyong; Selvin, Elizabeth; Rotter, Jerome I.; Langenberg, Claudia; Barroso, Inês; Meigs, James
    Background: Glycated hemoglobin (HbA1c) is used to diagnose type 2 diabetes (T2D) and assess glycemic control in patients with diabetes. Previous genome-wide association studies (GWAS) have identified 18 HbA1c-associated genetic variants. These variants proved to be classifiable by their likely biological action as erythrocytic (also associated with erythrocyte traits) or glycemic (associated with other glucose-related traits). In this study, we tested the hypotheses that, in a very large scale GWAS, we would identify more genetic variants associated with HbA1c and that HbA1c variants implicated in erythrocytic biology would affect the diagnostic accuracy of HbA1c. We therefore expanded the number of HbA1c-associated loci and tested the effect of genetic risk-scores comprised of erythrocytic or glycemic variants on incident diabetes prediction and on prevalent diabetes screening performance. Throughout this multiancestry study, we kept a focus on interancestry differences in HbA1c genetics performance that might influence race-ancestry differences in health outcomes. Methods & findings Using genome-wide association meta-analyses in up to 159,940 individuals from 82 cohorts of European, African, East Asian, and South Asian ancestry, we identified 60 common genetic variants associated with HbA1c. We classified variants as implicated in glycemic, erythrocytic, or unclassified biology and tested whether additive genetic scores of erythrocytic variants (GS-E) or glycemic variants (GS-G) were associated with higher T2D incidence in multiethnic longitudinal cohorts (N = 33,241). Nineteen glycemic and 22 erythrocytic variants were associated with HbA1c at genome-wide significance. GS-G was associated with higher T2D risk (incidence OR = 1.05, 95% CI 1.04–1.06, per HbA1c-raising allele, p = 3 × 10−29); whereas GS-E was not (OR = 1.00, 95% CI 0.99–1.01, p = 0.60). In Europeans and Asians, erythrocytic variants in aggregate had only modest effects on the diagnostic accuracy of HbA1c. Yet, in African Americans, the X-linked G6PD G202A variant (T-allele frequency 11%) was associated with an absolute decrease in HbA1c of 0.81%-units (95% CI 0.66–0.96) per allele in hemizygous men, and 0.68%-units (95% CI 0.38–0.97) in homozygous women. The G6PD variant may cause approximately 2% (N = 0.65 million, 95% CI 0.55–0.74) of African American adults with T2D to remain undiagnosed when screened with HbA1c. Limitations include the smaller sample sizes for non-European ancestries and the inability to classify approximately one-third of the variants. Further studies in large multiethnic cohorts with HbA1c, glycemic, and erythrocytic traits are required to better determine the biological action of the unclassified variants. Conclusions: As G6PD deficiency can be clinically silent until illness strikes, we recommend investigation of the possible benefits of screening for the G6PD genotype along with using HbA1c to diagnose T2D in populations of African ancestry or groups where G6PD deficiency is common. Screening with direct glucose measurements, or genetically-informed HbA1c diagnostic thresholds in people with G6PD deficiency, may be required to avoid missed or delayed diagnoses.
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    Genetically Driven Hyperglycemia Increases Risk of Coronary Artery Disease Separately From Type 2 Diabetes
    (American Diabetes Association, 2017) Merino, Jordi; Leong, Aaron; Posner, Daniel C.; Porneala, Bianca; Masana, Lluís; Dupuis, Josée; Florez, Jose
    OBJECTIVE This study tested the hypothesis that genetically raised hyperglycemia increases coronary artery disease (CAD) risk separately from the risk conferred by type 2 diabetes as a whole. RESEARCH DESIGN AND METHODS We conducted a Mendelian randomization (MR) analysis using summary-level statistics from the largest published meta-analyses of genome-wide association studies (GWAS) for fasting glucose (FG) (n = 133,010 participants free of diabetes) and CAD (n = 63,746 case subjects and 130,681 control subjects) of predominantly European ancestry. FG-increasing variants associated with type 2 diabetes from the largest GWAS for type 2 diabetes were excluded. Variants with pleiotropic effects on other CAD risk factors (blood lipids, blood pressure, and obesity) were excluded using summary-level data from the largest published GWAS. Data from the Framingham Heart Study were used to validate the MR instrument and to build an FG genetic risk score (GRS). RESULTS In an instrumental variable analysis comprising 12 FG-raising variants, a 1 mmol/L increase in FG revealed an effect-size estimate of 1.43 CAD odds (95% CI 1.14–1.79). The association was preserved after excluding variants for heterogeneity and pleiotropic effects on other CAD risk factors (odds ratio [OR] 1.33 [95% CI 1.02–1.73]). The 12 FG-increasing variants did not significantly increase type 2 diabetes risk (OR 1.05 [95% CI 0.91–1.23]), and its prevalence was constant across FG GRS quintiles (P = 0.72). CONCLUSIONS Our data support that genetic predisposition to hyperglycemia raises the odds of CAD separately from type 2 diabetes and other CAD risk factors. These findings suggest that modulating glycemia may provide cardiovascular benefit.
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    A Mendelian randomization study of the effect of type-2 diabetes on coronary heart disease
    (Nature Pub. Group, 2015) Ahmad, Omar S.; Morris, John A.; Mujammami, Muhammad; Forgetta, Vincenzo; Leong, Aaron; Li, Rui; Turgeon, Maxime; Greenwood, Celia M.T.; Thanassoulis, George; Meigs, James; Sladek, Robert; Richards, J. Brent
    In observational studies, type-2 diabetes (T2D) is associated with an increased risk of coronary heart disease (CHD), yet interventional trials have shown no clear effect of glucose-lowering on CHD. Confounding may have therefore influenced these observational estimates. Here we use Mendelian randomization to obtain unconfounded estimates of the influence of T2D and fasting glucose (FG) on CHD risk. Using multiple genetic variants associated with T2D and FG, we find that risk of T2D increases CHD risk (odds ratio (OR)=1.11 (1.05–1.17), per unit increase in odds of T2D, P=8.8 × 10−5; using data from 34,840/114,981 T2D cases/controls and 63,746/130,681 CHD cases/controls). FG in non-diabetic individuals tends to increase CHD risk (OR=1.15 (1.00–1.32), per mmol·per l, P=0.05; 133,010 non-diabetic individuals and 63,746/130,681 CHD cases/controls). These findings provide evidence supporting a causal relationship between T2D and CHD and suggest that long-term trials may be required to discern the effects of T2D therapies on CHD risk.