Stratifying type 2 diabetes cases by BMI identifies genetic risk variants in LAMA1 and enrichment for risk variants in lean compared to obese cases.

Stratifying type 2 diabetes cases by BMI identifies genetic risk variants in LAMA1 and enrichment for risk variants in lean compared to obese cases.

Common diseases such as type 2 diabetes are phenotypically heterogeneous. Obesity is a major risk factor for type 2 diabetes, but patients vary appreciably in body mass index. We hypothesized that the genetic predisposition to the disease may be different in lean (BMI<25 Kg/m²) compared to obese...

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Main Authors: John R B Perry, Benjamin F Voight, Loïc Yengo, Najaf Amin, Josée Dupuis, Martha Ganser, Harald Grallert, Pau Navarro, Man Li, Lu Qi, Valgerdur Steinthorsdottir, Robert A Scott, Peter Almgren, Dan E Arking, Yurii Aulchenko, Beverley Balkau, Rafn Benediktsson, Richard N Bergman, Eric Boerwinkle, Lori Bonnycastle, Noël P Burtt, Harry Campbell, Guillaume Charpentier, Francis S Collins, Christian Gieger, Todd Green, Samy Hadjadj, Andrew T Hattersley, Christian Herder, Albert Hofman, Andrew D Johnson, Anna Kottgen, Peter Kraft, Yann Labrune, Claudia Langenberg, Alisa K Manning, Karen L Mohlke, Andrew P Morris, Ben Oostra, James Pankow, Ann-Kristin Petersen, Peter P Pramstaller, Inga Prokopenko, Wolfgang Rathmann, William Rayner, Michael Roden, Igor Rudan, Denis Rybin, Laura J Scott, Gunnar Sigurdsson, Rob Sladek, Gudmar Thorleifsson, Unnur Thorsteinsdottir, Jaakko Tuomilehto, Andre G Uitterlinden, Sidonie Vivequin, Michael N Weedon, Alan F Wright, MAGIC, DIAGRAM Consortium, GIANT Consortium, Frank B Hu, Thomas Illig, Linda Kao, James B Meigs, James F Wilson, Kari Stefansson, Cornelia van Duijn, David Altschuler, Andrew D Morris, Michael Boehnke, Mark I McCarthy, Philippe Froguel, Colin N A Palmer, Nicholas J Wareham, Leif Groop, Timothy M Frayling, Stéphane Cauchi
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2012-05-01
Series:PLoS Genetics
Online Access:https://journals.plos.org/plosgenetics/article/file?id=10.1371/journal.pgen.1002741&type=printable
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Summary:Common diseases such as type 2 diabetes are phenotypically heterogeneous. Obesity is a major risk factor for type 2 diabetes, but patients vary appreciably in body mass index. We hypothesized that the genetic predisposition to the disease may be different in lean (BMI<25 Kg/m²) compared to obese cases (BMI≥30 Kg/m²). We performed two case-control genome-wide studies using two accepted cut-offs for defining individuals as overweight or obese. We used 2,112 lean type 2 diabetes cases (BMI<25 kg/m²) or 4,123 obese cases (BMI≥30 kg/m²), and 54,412 un-stratified controls. Replication was performed in 2,881 lean cases or 8,702 obese cases, and 18,957 un-stratified controls. To assess the effects of known signals, we tested the individual and combined effects of SNPs representing 36 type 2 diabetes loci. After combining data from discovery and replication datasets, we identified two signals not previously reported in Europeans. A variant (rs8090011) in the LAMA1 gene was associated with type 2 diabetes in lean cases (P = 8.4×10⁻⁹, OR = 1.13 [95% CI 1.09-1.18]), and this association was stronger than that in obese cases (P = 0.04, OR = 1.03 [95% CI 1.00-1.06]). A variant in HMG20A--previously identified in South Asians but not Europeans--was associated with type 2 diabetes in obese cases (P = 1.3×10⁻⁸, OR = 1.11 [95% CI 1.07-1.15]), although this association was not significantly stronger than that in lean cases (P = 0.02, OR = 1.09 [95% CI 1.02-1.17]). For 36 known type 2 diabetes loci, 29 had a larger odds ratio in the lean compared to obese (binomial P = 0.0002). In the lean analysis, we observed a weighted per-risk allele OR = 1.13 [95% CI 1.10-1.17], P = 3.2×10⁻¹⁴. This was larger than the same model fitted in the obese analysis where the OR = 1.06 [95% CI 1.05-1.08], P = 2.2×10⁻¹⁶. This study provides evidence that stratification of type 2 diabetes cases by BMI may help identify additional risk variants and that lean cases may have a stronger genetic predisposition to type 2 diabetes.
ISSN:1553-7390
1553-7404

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