NIH Public Access Author Manuscript Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Published in final edited form as: Obesity (Silver Spring). 2013 September ; 21(9): E520–E526. doi:10.1002/oby.20459. NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Variation at the Melanocortin 4 Receptor gene and response to weight-loss interventions in the Diabetes Prevention Program Qing Pan1, Linda M. Delahanty2,3, Kathleen A. Jablonski1, William C. Knowler4, Steven E. Kahn5, Jose C. Florez3,6,7, and Paul W. Franks8,9,10 for the Diabetes Prevention Program Research Group* 1The Biostatistics Center, George Washington University, Rockville, Maryland 2Diabetes Research Center, Massachusetts General Hospital, Boston, Massachusetts 3Department of Medicine, Harvard Medical School, Boston, Massachusetts 4National Institute of Diabetes and Digestive and Kidney Diseases, Phoenix, Arizona 5VA Puget Sound Health Care System and University of Washington, Seattle, WA 6Center for Human Genetic Research and Diabetes Research Center (Diabetes Unit), Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts 7Program in Medical and Population Genetics, Broad Institute, Cambridge, Massachusetts 8Department of Clinical Sciences, Lund University, Malmö, Sweden 9Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts 10Department of Public Health & Clinical Medicine, Umeå University, Umeå, Sweden Abstract Objective—To assess associations and genotype × treatment interactions for melanocortin 4 receptor (MC4R) locus variants and obesity-related traits. Design and Methods—Diabetes Prevention Program (DPP) participants (N=3,819, of whom 3,356 were genotyped for baseline and 3,234 for longitudinal analyses) were randomized into intensive lifestyle modification (diet, exercise, weight loss), metformin or placebo control. Adiposity was assessed in a subgroup (n=909) using computed tomography. All analyses were adjusted for age, sex, ethnicity and treatment. Results—The rs1943218 minor allele was nominally associated with short-term (6 month; P=0.032) and long-term (2 year; P=0.038) weight change. Eight SNPs modified response to treatment on short-term (rs17066856, rs9966412, rs17066859, rs8091237, rs17066866, rs7240064) or long-term (rs12970134, rs17066866) reduction in body weight, or diabetes incidence (rs17066829) (all Pinteraction <0.05). Corresponding author/Reprint request contact: Paul W. Franks, Diabetes Prevention Program Coordinating Center, The Biostatistics Center, George Washington University, 6110 Executive Blvd., Suite 750, Rockville, MD 20852. Telephone: (301) 881-9260, Fax: (301) 881-8752, paul.franks@med.lu.se or dppmail@biostat.bsc.gwu.edu. *A list of Diabetes Prevention Program Research Group investigators is provided in the Appendix Author contributions: QP, LMD, LCF, and PWF designed the research; WCK and SEK conducted the research; QP and KAJ performed the statistical analysis; QP and PWF wrote the paper; QP and PWF have primary responsibility for final content. All authors contributed with critical comments on the paper and approved its submission. COMPETING INTERESTS The authors have no competing interests Pan et al. Page 2 Conclusion—This is the first study to comprehensively assess the role of MC4R variants and weight regulation in a weight loss intervention trial. One MC4R variant was directly associated with obesity-related traits or diabetes; numerous other variants appear to influence body weight and diabetes risk by modifying the protective effects of the DPP interventions. Keywords MC4R; Randomized Controlled Trial; Lifestyle; Metformin; Gene-Environment Interaction; Genetic; Obesity; Diabetes Prevention Program; Adiposity NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript INTRODUCTION Obesity is a highly heritable(1), complex trait presumed to originate from interactions between multiple genetic and environment risk factors. Several well-defined genetic causes of monogenic obesity are known(2), as are multiple low-penetrance obesogenic variants that are prevalent in the general population(3). One of the loci implicated in both monogenic and common forms of obesity is the melanocortin 4 receptor (encoded by MC4R). Mutations in MC4R are the most frequent known genetic causes of congenital obesity(4) and a variant mapping to a region upstream of MC4R is strongly associated with variations in BMI and adiposity in multiple populations(5). MC4R variants have also been associated with energy balance behaviors(6, 7), blood pressure(8), dyslipidemia(9), stature(4), and type 2 diabetes(10). Two important risk factors for obesity are physical inactivity and excessive caloric intake. Thus, studies focusing on the interactions between obesity-predisposing genes and therapies that influence body weight may help elucidate the molecular mechanisms underlying obesity and its consequences, such as cardiovascular disease, certain cancers, osteoarthritis, and type 2 diabetes. In this regard, lifestyle interventions focused on diet, exercise, and pharmacologic interventions that influence weight loss (e.g., metformin) are relevant. The purpose of this study was to extend earlier studies that center on MC4R variants and BMI by examining whether MC4R variation per se is associated with obesity-related traits over time or type 2 diabetes incidence. We tagged the entire MC4R region and examined whether associations with obesity-related traits are mediated by dietary preference or physical activity or modified by metformin treatment or lifestyle intervention. All analyses were performed within the Diabetes Prevention Program (DPP), a randomized clinical trial of intensive lifestyle modification, metformin or troglitazone therapy, or placebo intervention. METHODS and PROCEDURES The Diabetes Prevention Program (DPP) The DPP was a multi-center randomized clinical trial. The study design and details of the preventive interventions have been described in detail previously(11-13). Briefly, nondiabetic, overweight persons (n=3,234) with raised fasting and post-challenge glucoses were randomized to placebo, metformin (850 mg twice daily), troglitazone (400 mg daily), or a Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 3 program of intensive lifestyle modification (aimed at ~7% weight loss and ~150 minutes of physical activity per week). A further 585 participants were randomized to receive troglitazone treatment; owing to liver toxicity, this aspect of the DPP trial was terminated early and only the baseline results were used in these analyses(11). Thus, a total of 3,819 participants were included in the baseline analyses reported here, whereas 3,234 are included in the prospective analyses. The principal endpoint in the DPP was the development of diabetes by confirmed oral glucose tolerance testing (OGTT). Other phenotypes, such as changes in weight, waist circumference, abdominal fat area, lipids, insulin and glucose, were also collected. The primary focus of this report is on the obesityrelated traits; the secondary focus is on diabetes incidence. Each of the 27 DPP centers obtained approval from their respective institutional review boards prior to initiation of the study protocol. Consent for genetic analyses was obtained in 87.9% (n=3,356/3,819) of participants who were originally assigned to a treatment arm in the DPP. Of the participants studied in this report, by self-report 56.1% were white, 20.4% African American, 16.7% Hispanic, 4.4% Asian American and 2.5% American Indian. Concordant with the entire DPP, the participants’ mean age at enrollment was 51 (SD=11) years and mean body mass index (BMI) was 34 (SD=7) kg/m2; (see Table 1). Quantification of energy intake, physical activity, and body composition In-person interviews were conducted to obtain data on calorie intake, percent of calories from fat and protein, absolute intake of fat and protein and food preference behaviors at baseline and 1 year later using the semi-quantitative DPP food frequency questionnaire (FFQ)(14). To evaluate food preference behaviors, we assessed the frequency of consumption of snacks, sweets and desserts, vegetables and fruits, expressed as servings per day. Occupational and leisure-time physical activity (LTPA) was assessed using the validated Modifiable Activity Questionnaire (MAQ) at baseline and annually thereafter(15). Weight and BMI were measured in all participants. Computed tomography (CT) was performed at baseline in 909 randomly selected subjects DPP participants, among whom 718 underwent a repeated measure at 12-months postrandomization to quantify subcutaneous and visceral fat areas (at the level of the lumbar 2-3 disc space)(16) and gave consent for genetic analyses. Among the participants with both baseline and one-year CT measurements, 241 were from the intensive lifestyle group, 246 from the metformin group and 231 from the placebo group. Genotyping SNPs were selected through multimarker tagging of the MC4R locus (as previously described(17)). Genotyping was performed by allele-specific primer extension of multiplex amplified products and detection with matrix-assisted laser desorption ionization-time of flight mass spectroscopy on a Sequenom iPLEX platform. The genotyping success rates for the SNPs studied here were >99%. All 20 SNPs were in Hardy-Weinberg equilibrium in all five ethnic groups (P>0.05). For each SNP, genomic location, alleles and their frequencies NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 4 are reported in Online Supplementary Table 1. Online Supplementary Figures 1a-e show the LD plots for these variants. NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Statistical analysis Analyses were performed using the SAS software (SAS Institute, Cary, NC). Weight loss and abdominal fat area follow-up data were normally distributed and linear regressions were employed for these outcomes. SNP associations with diabetes incidence were assessed with Cox proportional hazards models. Potential mediating effects of leisure time physical activity (LTPA) and energy intake were tested by comparing the SNP regression coefficients with and without adjustment for the potential mediators(17). All models were adjusted for genotype, intervention, baseline value of the dependent variable, age at randomization, sex, and self-reported ethnicity. Further adjustment for study center made no material difference to the results (data not shown) and is thus not included in the current models. To determine whether it was appropriate to combine data from different treatment and ethnicity groups, we tested genotype × treatment and genotype × ethnicity interactions. If these tests were statistically significant (P<0.05), we stratified by group; otherwise data were pooled and adjusted for treatment and/or ethnicity. For all variants, we analyzed additive genetic models. Two-sided P-values without multiplicity adjustment are reported. MC4R is a strong candidate gene for obesity-related traits(4); thus, the prior probability that variants at this locus are associated with obesity traits is likely to be above the null. Moreover, although the DPP is the largest randomized controlled trial of intensive lifestyle modification, it is modestly powered for most of the tests performed here (see:(18)) for description of the statistical power characteristics of the DPP). Thus, correcting for multiple testing is likely to increase type 2 error (false-negative) rates. Nonetheless, we are conscious that many readers will be keen to compare the nominal test statistics with those corrected for multiple testing. After considering the linkage disequilibrium between the 20 SNPs, we determined that there are 17.46 independent SNP tests(19). Therefore, instead of the Bonferroni cutoff of 0.05, a cutoff of 0.05/17.46=0.003 is used to determine a conservative estimate of statistical significance for the results reported in this paper. Exploratory analyses were performed to determine whether any of the statistically significant genetic effects detected in the main analyses were likely to be mediated by specific lifestyle factors. The following factors were considered potential intermediate factors (mediators) of the observed genetic effects: leisure time physical activity in MET-hrs per week (metabolic equivalents), total caloric intake (kcal/day), percent of calories from fat, percent of calories from protein, fat intake (g/day), protein intake (g/day), snacking (number of snacks/day), sweet and dessert (servings/day), vegetable consumption (servings/day) and fruit consumption (servings/day). While testing each candidate mediator, two models were fit, one with the candidate mediator as a covariate and the other without. From each pair of models, the difference in the two SNP regression coefficients and the standard errors of these differences were calculated(18). In these analyses, a statistically significant non-zero difference represents a discrepancy between the marginal SNP effect estimate and the SNP effect estimate that is conditional on Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 5 the putative mediator, thus validating the intermediate function of the mediator from genotype to the outcome. NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript RESULTS Participant characteristics Participant characteristics for the DPP cohort used for genetic analyses are reported elsewhere(17). Table 1 reports anthropometric traits, energy intake, and physical activity at baseline, as well as the weight loss outcomes. Table 2 shows results from the analysis focused on the entire MC4R region; the table shows regression coefficients (representing the average difference in the dependent variable for each additional copy of the minor allele) and P values for all 20 MC4R SNPs and baseline weight and BMI in DPP participants. After adjustment for age, sex, and self-reported ethnicity, no SNP was statistically associated with baseline weight or BMI. SNP associations with change in weight or adiposity Tables 3 and 4 list the overall and treatment specific genetic effects for the three major outcomes: short-term (baseline to 6 months) and long-term (baseline to 2 years) weight change, and diabetes incidence. The major ‘C’ allele at SNP rs1943218 was associated with less short-term (P=0.032) and long-term (P=0.038) weight loss. Seven SNPs modified response to treatment on short-term (rs17066856, rs9966412, rs17066859, rs8091237, rs17066866, rs7240064) or long-term (rs12970134, rs17066866) reduction in body weight. Among them, nominally statistically significant associations with weight change for rs7240064 in the placebo arm and rs9966412 and rs17066859 in the metformin arm were observed, with each SNP’s minor allele being associated with less short-term weight loss. The minor allele of rs17066866 was associated with less short-term (P=0.006) and less longterm (P=0.004) weight loss in the lifestyle intervention group, the latter of which approached the multiple-testing corrected significance threshold (P=0.003). Associations with diabetes incidence Table 4 shows the SNP association results for type 2 diabetes incidence. SNP rs17066829 showed nominal evidence of interaction with treatment for diabetes risk (Pinteraction <0.05); for example, each copy of the minor allele at SNP rs17066829 corresponded to a HR of 0.80 (95% CI: 0.64-1.00) in the lifestyle group, which contrasted the effect observed in the placebo group (HR=1.09; 95% CI: 0.92-1.29). Examining dietary factors and physical activity as putative mediators of genetic effects on obesity traits Potential mediators were examined for all SNP associations and interactions that were of at least nominal statistical significance (as shown in Tables 3 and 4). No significant differences between the SNP effects before or after the adjustment of each potential mediator were detected. Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 6 DISCUSSION MC4R is a strong candidate gene for diabetes and obesity-related traits. The rs17782313 SNP, which is upstream of the MC4R locus, has for example been reliably associated with common obesity in a GWAS meta-analysis(5) and also in the DPP(17), but the MC4R region in general has been of continued interest in obesity research for many years(3,5,10,21), largely because of its established role in monogenic obesity(4). Hence, we examined common variation across MC4R to seek a more detailed understanding of the role the gene plays in obesity and diabetes, and to determine whether the apparent obesogenic effect of variation at this locus is modified by weight loss interventions in the DPP. In analyses adjusted for multiple statistical comparisons, we found nominal evidence of association between the rs1943218 variant and short- (baseline to 6 months) and long(baseline to two years) term weight loss. Interactions between metformin treatment and the rs9966412 and rs17066859 variants on short-term weight loss were also found. Moreover, we observed a nominally significant statistical interaction between the rs17066829 SNP and treatment on diabetes incidence, which is of potential interest, as a recent study also showed that this variant was associated with BMI(22). MC4R is centrally expressed and binds the α, β and γ isoforms of melanocortin-stimulating hormone (MSH) and adrenocoticotropic hormone (ACTH) with varying affinity, while Agouti and Agouti-related protein (AgRP) are endogenous MC4R antagonists(23). Mc4r knockout mice are hyperphagic and are prone to maturity-onset obesity(24). Although restricting food availability reduces body weight in female Mc4r -/- mice, these animals remain susceptible to obesity(25), indicating that MC4R ablation also influences energy expenditure; direct evidence for this comes from observations that Mc4r null mice have lower resting oxidative energy metabolism(25) and dark-phase locomotor activity(25,26) compared with wild type animals. People heterozygous for specific MC4R mutations are MC4R deficient and are often hyperphagic, heavier and taller, with more fat and lean mass, and have higher bone mineral content than people who do not carry these mutations(27). Genome-wide scans of White Europeans have identified two independent signals for BMI at the MC4R locus, which are also associated with adipose mass and type 2 diabetes(10). One of the most thorough investigations of the MC4R locus in humans to date was undertaken by Thearle et al in a study of 6,760 persons of predominantly Pima Indian ancestry(28). The authors sequenced the MC4R exon to discover six low frequency mutations (~2.4%), which were subsequently functionally interrogated in vitro. These mutations conveyed an effect on weight gain but this was only evident in childhood, and the effect on type 2 diabetes that the authors observed was mediated by adult BMI. MC4R is a strong candidate gene for obesity-related traits; thus, the prior probability that variants at this locus are associated with obesity traits is likely to be above the null, in which case the nominal P-values we report here may be somewhat conservative estimates of the underlying probability that an association exists. Moreover, although the DPP is the largest randomized controlled trial of intensive lifestyle modification, it is modestly powered for most of the tests performed here(17) for description of the statistical power characteristics of the DPP). Thus, correcting for multiple testing is likely to increase type 2 error (false- NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 7 negative) rates. Nonetheless, we are conscious that many readers will be keen to compare the nominal test statistics with those corrected for multiple testing, which is why the multiple-test corrected significance threshold is given above. Assessing epidemiological observations in an experimental setting is important step in the process of translating such observations into preventive action. Nevertheless, it is important to bear in mind that DPP participants were recruited on the basis of being overweight or obese and having impaired fasting and post-challenge glucose. Thus, the findings from this study may not generalize to other population subgroups. We were also unable to identify behavioral factors that might mediate the effects of MC4R on obesity-related traits, which would have aided the interpretation of the results described above. Our study was also limited by the absence of information on lifestyle behaviors after 12 months of intervention, which may have hampered the detection of mediators. In summary, we have conducted the first comprehensive analysis of common genomic variation at the MC4R locus in relation to changes in body composition and incidence of type 2 diabetes within a randomized controlled trial of weight loss interventions. Our findings, that several MC4R variants are nominally related to these traits, in some instances by modifying the effects of weight loss interventions on diabetes incidence and adipose accumulation, adds novel information on the role of the MC4R locus in the development of obesity and type 2 diabetes. NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Supplementary Material Refer to Web version on PubMed Central for supplementary material. Acknowledgments The National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) of the National Institutes of Health provided funding to the clinical centers and the Coordinating Center for the design and conduct of the study; collection, management, analysis, and interpretation of the data (U01 DK048489). The Southwestern American Indian Centers were supported directly by the NIDDK and the Indian Health Service. The General Clinical Research Center Program, National Center for Research Resources supported data collection at many of the clinical centers. Funding for data collection and participant support was also provided by the Office of Research on Minority Health, the National Institute of Child Health and Human Development, the National Institute on Aging, the Centers for Disease Control and Prevention, the Office of Research on Women’s Health, the Department of Veterans Affairs, and the American Diabetes Association. Bristol-Myers Squibb and Parke-Davis provided medication. This research was also supported, in part, by the intramural research program of the NIDDK. LifeScan Inc., Health O Meter, Hoechst Marion Roussel, Inc., Merck-Medco Managed Care, Inc., Merck and Co., Nike Sports Marketing, Slim Fast Foods Co., and Quaker Oats Co. donated materials, equipment, or medicines for concomitant conditions. McKesson BioServices Corp., Matthews Media Group, Inc., and the Henry M. Jackson Foundation provided support services under subcontract with the Coordinating Center. The opinions expressed are those of the investigators and do not necessarily reflect the views of the Indian Health Service or other funding agencies. A complete list of Centers, investigators, and staff can be found in the Appendix. The investigators gratefully acknowledge the commitment and dedication of all participants in the DPP, without whom this work would not have been possible. This work was funded by R01 DK072041-02 to JCF and KAJ (PWF and WCK are unpaid co-investigators). PWF was supported by grants from Novo Nordisk, the Swedish Research Council, the Swedish Heart-Lung Foundation and the Swedish Diabetes Association. SEK is supported in part by the Department of Veterans Affairs. JCF has received consulting honoraria from Novartis, Lilly and Pfizer. Grants: NIH/NIDDK U01-DK048489 Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 8 Appendix: DPP Research Group Investigators Pennington Biomedical Research Center (Baton Rouge, LA) George A. Bray, MD* Iris W. Culbert, BSN, RN, CCRC** Catherine M. Champagne, PhD, RD Barbara Eberhardt, RD, LDN Frank Greenway, MD Fonda G. Guillory, LPN April A. Herbert, RD Michael L. Jeffirs, LPN Betty M. Kennedy, MPA Jennifer C. Lovejoy, PhD NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Laura H. Morris, BS Lee E. Melancon, BA, BS Donna Ryan, MD Deborah A. Sanford, LPN Kenneth G. Smith, BS, MT Lisa L. Smith, BS Julia A. St.Amant, RTR Richard T. Tulley, PhD Paula C. Vicknair, MS, RD Donald Williamson, PhD Jeffery J. Zachwieja, PhD University of Chicago (Chicago, IL) Kenneth S. Polonsky, MD* Janet Tobian, MD, PhD* David Ehrmann, MD* Margaret J. Matulik, RN, BSN** Bart Clark, MD Kirsten Czech, MS Catherine DeSandre, BA Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 9 Ruthanne Hilbrich, RD Wylie McNabb, EdD NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Ann R. Semenske, MS, RD Jefferson Medical College (Philadelphia, PA) Jose F. Caro, MD* Pamela G. Watson, RN, ScD* Barry J. Goldstein, MD, PhD* Kellie A. Smith, RN, MSN** Jewel Mendoza, RN, BSN** Renee Liberoni, MPH Constance Pepe, MS, RD John Spandorfer, MD University of Miami (Miami, FL) Richard P. Donahue, PhD* Ronald B. Goldberg, MD* Ronald Prineas, MD, PhD* Patricia Rowe, MPA** Jeanette Calles, MSEd Paul Cassanova-Romero, MD Hermes J. Florez, MD Anna Giannella, RD, MS Lascelles Kirby, MS Carmen Larreal Valerie McLymont, RN Jadell Mendez Juliet Ojito, RN Arlette Perry, PhD Patrice Saab, PhD The University of Texas Health Science Center (San Antonio, TX) Steven M. Haffner, MD, MPH* Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 10 Maria G. Montez, RN, MSHP, CDE** Carlos Lorenzo, MD, PhD NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Arlene Martinez, RN, BSN, CDE University of Colorado (Denver, CO) Richard F. Hamman, MD, DrPH* Patricia V. Nash, MS** Lisa Testaverde, MS** Denise R. Anderson, RN, BSN Larry B. Ballonoff, MD Alexis Bouffard, MA, B. Ned Calonge, MD, MPH Lynne Delve Martha Farago, RN James O. Hill, PhD Shelley R. Hoyer, BS Bonnie T. Jortberg, MS, RD, CDE Dione Lenz, RN, BSN Marsha Miller, MS, RD David W. Price, MD Judith G. Regensteiner, PhD Helen Seagle, MS, RD Carissa M. Smith, BS Sheila C. Steinke, MS Brent VanDorsten, PhD Joslin Diabetes Center (Boston, MA) Edward S. Horton, MD* Kathleen E. Lawton, RN** Ronald A. Arky, MD Marybeth Bryant Jacqueline P. Burke, BSN Enrique Caballero, MD Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 11 Karen M. Callaphan, BA Om P. Ganda, MD NIH-PA Author Manuscript NIH-PA Author Manuscript (Seattle, WA) NIH-PA Author Manuscript Therese Franklin Sharon D. Jackson, MS, RD, CDE Alan M. Jacobsen, MD Lyn M. Kula, RD Margaret Kocal, RN, CDE Maureen A. Malloy, BS Maryanne Nicosia, MS, RD Cathryn F. Oldmixon, RN Jocelyn Pan, BS, MPH Marizel Quitingon Stacy Rubtchinsky, BS Ellen W. Seely, MD Dana Schweizer, BSN Donald Simonson, MD Fannie Smith, MD Caren G. Solomon, MD, MPH James Warram, MD VA Puget Sound Health Care System and University of Washington Steven E. Kahn, MB, ChB* Brenda K. Montgomery, RN, BSN, CDE** Wilfred Fujimoto, MD Robert H. Knopp, MD Edward W. Lipkin, MD Michelle Marr, BA Dace Trence, MD University of Tennessee (Memphis, TN) Abbas E. Kitabchi, PhD, MD, FACP* Mary E. Murphy, RN, MS, CDE, MBA** Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 12 William B. Applegate, MD, MPH Michael Bryer-Ash, MD NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Sandra L. Frieson, RN Raed Imseis, MD Helen Lambeth, RN, BSN Lynne C. Lichtermann, RN, BSN Hooman Oktaei, MD Lily M.K. Rutledge, RN, BSN Amy R. Sherman, RD, LD Clara M. Smith, RD, MHP, LDN Judith E. Soberman, MD Beverly Williams-Cleaves, MD Northwestern University’s Feinberg School of Medicine (Chicago, IL) Boyd E. Metzger, MD* Mariana K. Johnson, MS, RN** Catherine Behrends Michelle Cook, MS Marian Fitzgibbon, PhD Mimi M. Giles, MS, RD Deloris Heard, MA Cheryl K.H. Johnson, MS, RN Diane Larsen, BS Anne Lowe, BS Megan Lyman, BS David McPherson, MD Mark E. Molitch, MD Thomas Pitts, MD Renee Reinhart, RN, MS Susan Roston, RN, RD Pamela A. Schinleber, RN, MS Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 13 Massachusetts General Hospital (Boston, MA) David M. Nathan, MD* Charles McKitrick, BSN** Heather Turgeon, BSN** Kathy Abbott Ellen Anderson, MS, RD Laurie Bissett, MS, RD Enrico Cagliero, MD Jose C. Florez, MD, PhD+ Linda Delahanty, MS, RD Valerie Goldman, MS, RD Alexandra Poulos NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript University of California-San Diego (San Diego, CA) Jerrold M. Olefsky, MD* Mary Lou Carrion-Petersen, RN, BSN** Elizabeth Barrett-Connor, MD Steven V. Edelman, MD Robert R. Henry, MD Javiva Horne, RD Simona Szerdi Janesch, BA Diana Leos, RN, BSN Sundar Mudaliar, MD William Polonsky, PhD Jean Smith, RN Karen Vejvoda, RN, BSN, CDE, CCRC St. Luke’s-Roosevelt Hospital (New York, NY) F. Xavier Pi-Sunyer, MD* Jane E. Lee, MS** David B. Allison, PhD Nancy J. Aronoff, MS, RD Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 14 Jill P. Crandall, MD Sandra T. Foo, MD NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Carmen Pal, MD Kathy Parkes, RN Mary Beth Pena, RN Ellen S. Rooney, BA Gretchen E.H. Van Wye, MA Kristine A. Viscovich, ANP Indiana University (Indianapolis, IN) David G. Marrero, PhD* Melvin J. Prince, MD* Susie M. Kelly, RN, CDE** Yolanda F. Dotson, BS Edwin S. Fineberg, MD John C. Guare, PhD Angela M. Hadden James M. Ignaut, MA Marcia L. Jackson Marion S. Kirkman, MD Kieren J. Mather, MD Beverly D. Porter, MSN Paris J. Roach, MD Nancy D. Rowland, BS, MS Madelyn L. Wheeler, RD Medstar Research Institute (Washington, DC) Robert E. Ratner, MD* Gretchen Youssef, RD, CDE** Sue Shapiro, RN, BSN, CCRC** Catherine Bavido-Arrage, MS, RD, LD Geraldine Boggs, MSN, RN Marjorie Bronsord, MS, RD, CDE Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 15 Ernestine Brown Wayman W. Cheatham, MD NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Susan Cola Cindy Evans Peggy Gibbs Tracy Kellum, MS, RD, CDE Claresa Levatan, MD Asha K. Nair, BS Maureen Passaro, MD Gabriel Uwaifo, MD University of Southern California/UCLA Research Center (Alhambra, CA) Mohammed F. Saad, MD* Maria Budget** Sujata Jinagouda, MD** Khan Akbar, MD Claudia Conzues Perpetua Magpuri Kathy Ngo Amer Rassam, MD Debra Waters Kathy Xapthalamous Washington University (St. Louis, MO) Julio V. Santiago, MD* (deceased) Samuel Dagogo-Jack, MD, MSc, FRCP, FACP* Neil H. White, MD, CDE* Samia Das, MS, MBA, RD, LD** Ana Santiago, RD** Angela Brown, MD Edwin Fisher, PhD Emma Hurt, RN Tracy Jones, RN Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 16 Michelle Kerr, RD Lucy Ryder, RN NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Cormarie Wernimont, MS, RD Johns Hopkins School of Medicine (Baltimore, MD) Christopher D. Saudek, MD* Vanessa Bradley, BA** Emily Sullivan, MEd, RN** Tracy Whittington, BS** Caroline Abbas Frederick L. Brancati, MD, MHS Jeanne M. Clark, MD Jeanne B. Charleston, RN, MSN Janice Freel Katherine Horak, RD Dawn Jiggetts Deloris Johnson Hope Joseph Kimberly Loman Henry Mosley Richard R. Rubin, PhD Alafia Samuels, MD Kerry J. Stewart, EdD Paula Williamson University of New Mexico (Albuquerque, NM) David S. Schade, MD* Karwyn S. Adams, RN, MSN** Carolyn Johannes, RN, CDE** Leslie F. Atler, PhD Patrick J. Boyle, MD Mark R. Burge, MD Janene L. Canady, RN, CDE Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 17 Lisa Chai, RN Ysela Gonzales, RN, MSN NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Doris A. Hernandez-McGinnis Patricia Katz, LPN Carolyn King Amer Rassam, MD Sofya Rubinchik, MD Willette Senter, RD Debra Waters, PhD Albert Einstein College of Medicine (Bronx, NY) Harry Shamoon, MD* Janet O. Brown, RN, MPH, MSN** Elsie Adorno, BS Liane Cox, MS, RD Jill Crandall, MD Helena Duffy, MS, C-ANP Samuel Engel, MD Allison Friedler, BS Crystal J. Howard-Century, MA Stacey Kloiber, RN Nadege Longchamp, LPN Helen Martinez, RN, MSN, FNP-C Dorothy Pompi, BA Jonathan Scheindlin, MD Elissa Violino, RD, MS Elizabeth Walker, RN, DNSc, CDE Judith Wylie-Rosett, EdD, RD Elise Zimmerman, RD, MS Joel Zonszein, MD University of Pittsburgh (Pittsburgh, PA) Trevor Orchard, MD* Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 18 Rena R. Wing, PhD* Gaye Koenning, MS, RD** NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript M. Kaye Kramer, BSN, MPH** Susan Barr, BS Miriam Boraz Lisa Clifford, BS Rebecca Culyba, BS Marlene Frazier Ryan Gilligan, BS Susan Harrier, MLT Louann Harris, RN Susan Jeffries, RN, MSN Andrea Kriska, PhD Qurashia Manjoo, MD Monica Mullen, MHP, RD Alicia Noel, BS Amy Otto, PhD Linda Semler, MS, RD Cheryl F. Smith, PhD Marie Smith, RN, BSN Elizabeth Venditti, PhD Valarie Weinzierl, BS Katherine V. Williams, MD, MPH Tara Wilson, BA University of Hawaii (Honolulu, HI) Richard F. Arakaki, MD* Renee W. Latimer, BSN, MPH** Narleen K. Baker-Ladao, BS Ralph Beddow, MD Lorna Dias, AA Jillian Inouye, RN, PhD Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 19 Marjorie K. Mau, MD Kathy Mikami, BS, RD NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Pharis Mohideen, MD Sharon K. Odom, RD, MPH Raynette U. Perry, AA Southwest American Indian Centers (Phoenix, AZ; Shiprock, NM; Zuni, NM) William C. Knowler, MD, DrPH*+ Norman Cooeyate** Mary A. Hoskin, RD, MS** Carol A. Percy, RN, MS** Kelly J. Acton, MD, MPH Vickie L. Andre, RN, FNP Rosalyn Barber Shandiin Begay, MPH Peter H. Bennett, MB, FRCP Mary Beth Benson, RN, BSN Evelyn C. Bird, RD, MPH Brenda A. Broussard, RD, MPH, MBA, CDE Marcella Chavez, RN, AS Tara Dacawyma Matthew S. Doughty, MD Roberta Duncan, RD Cyndy Edgerton, RD Jacqueline M. Ghahate Justin Glass, MD Martia Glass, MD Dorothy Gohdes, MD Wendy Grant, MD Robert L. Hanson, MD, MPH Ellie Horse Louise E. Ingraham, MS, RD, LN Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 20 Merry Jackson Priscilla Jay NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Roylen S. Kaskalla David Kessler, MD Kathleen M. Kobus, RNC-ANP Jonathan Krakoff, MD Catherine Manus, LPN Sara Michaels, MD Tina Morgan Yolanda Nashboo (deceased) Julie A. Nelson, RD Steven Poirier, MD Evette Polczynski, MD Mike Reidy, MD Jeanine Roumain, MD, MPH Debra Rowse, MD Sandra Sangster Janet Sewenemewa Darryl Tonemah, PhD Charlton Wilson, MD Michelle Yazzie George Washington University Biostatistics Center (DPP Coordinating Center Rockville, MD) Raymond Bain, PhD* Sarah Fowler, PhD* Tina Brenneman** Solome Abebe Julie Bamdad, MS Jackie Callaghan Sharon L. Edelstein, ScM Yuping Gao Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 21 Kristina L. Grimes Nisha Grover NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Lori Haffner, MS Steve Jones Tara L. Jones Richard Katz, MD John M. Lachin, ScD Pamela Mucik Robert Orlosky James Rochon, PhD Alla Sapozhnikova Hanna Sherif, MS Charlotte Stimpson Marinella Temprosa, MS Fredricka Walker-Murray Central Biochemistry Laboratory (Seattle, WA) Santica Marcovina, PhD, ScD* Greg Strylewicz, PhD** F. Alan Aldrich Carotid Ultrasound Dan O’Leary, MD* CT Scan Reading Center Elizabeth Stamm, MD* Epidemiological Cardiology Research Center- Epicare (Winston-Salem, NC) Pentti Rautaharju, MD, PhD* Ronald J. Prineas, MD, PhD*/* Teresa Alexander Charles Campbell, MS Sharon Hall Yabing Li, MD Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 22 Margaret Mills Nancy Pemberton, MS NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Farida Rautaharju, PhD Zhuming Zhang, MD Nutrition Coding Center (Columbia, SC) Elizabeth Mayer-Davis, PhD* Robert R. Moran, PhD** Quality of Well-Being Center (La Jolla, CA) Ted Ganiats, MD* Kristin David, MHP* Andrew J. Sarkin, PhD* Erik Groessl, PhD NIH/NIDDK (Bethesda, MD) R. Eastman, MD Judith Fradkin, MD Sanford Garfield, PhD Centers for Disease Control & Prevention (Atlanta, GA) Edward Gregg, PhD Ping Zhang, PhD University of Michigan (Ann Arbor, MI) William H. Herman, MD, MPH +Genetics Working Group Jose C. Florez, MD, PhD1, 2 David Altshuler, MD, PhD1, 2 Paul I.W. de Bakker, PhD2 Paul W. Franks, PhD, MPhil, MS6, 7, 8 Robert L. Hanson, MD, MPH3 Kathleen Jablonski, PhD5 William C. Knowler, MD, DrPH3 Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 23 Jarred B. McAteer, AB1, 2 Toni I. Pollin, PhD4 NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Alan R. Shuldiner, MD4 *denotes Principal Investigator **denotes Program Coordinator 1=Massachusetts General Hospital 2=Broad Institute 3=NIDDK 4=University of Maryland 5=Coordinating Center 6=Lund University, Sweden 7=Umeå University, Sweden 8=Harvard School of Public Health References 1. 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Diabetes. 2012; 61:250–257. [PubMed: 22106157] NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Pan et al. Page 25 What is already known about this subject NIH-PA Author Manuscript NIH-PA Author Manuscript NIH-PA Author Manuscript • MC4R encodes one of five melanocortin receptors that control energy balance, adipose deposition, and other metabolic traits MC4R mutations are the most frequent known cause of human monogenic obesity Common variants in MC4R are associated with common obesity and type 2 diabetes • • What this study adds • This study provides the first a comprehensive assessment of MC4R variation in relation to dynamic body weight phenotypes in a randomized controlled trial of weight loss interventions Several MC4R variants appear to modify the effects of the DPP weight loss interventions on reductions in body weight and diabetes incidence • Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. Table 1 Pan et al. Characteristics of DPP study participants included in these analyses (N=3,891) Lifestyle 1079 32% 51 (11) 94 (21) 34 (7) 105 (15) 308 (125) 443 (152) 200 (85) 163 (65) 16 (22) 2137 (1071) 6.7 (5.6) 5.4 (7.6) 50 80 100 74 <0.001 2.1 (5.7) 0.0 (5.5) <0.001 2.3 (4.0) 0.3 (4.0) <0.001 2144 (986) 2098 (1052) 2118 (989) 0.739 16 (26) 17 (29) 15 (16) 0.390 158 (65) 159 (65) 0.500 195 (83) 199 (90) 0.701 433 (154) 449 (151) 0.408 301 (129) 314 (127) 0.449 105 (14) 105 (14) 104 (14) 0.605 34 (7) 34 (7) 34 (6) 0.311 94 (20) 94 (20) 93 (19) 0.774 51 (10) 50 (10) 50 (10) 0.469 34% 31% 34% 0.404 1073 1082 585 Metformin Placebo Troglitazonea P-value Baseline Characteristic N Male Age (years) Weight (kg) BMI (kg/m2) Waist circumference (cm) SAT L2-3 (cm2) SAT L4-5 (cm2) VAT L2-3 (cm2) VAT L4-5 (cm2) LTPA (MET-hrs/wk) Energy Intake (kcal/day) Short-term(6m) weight loss(kg) Long-term(2y) weight loss(kg) Diabetes Incidence per 1,000 p-yr Data are percentage or Mean (SD), stratified by treatment assignment. P-values from ANOVA F-tests and Chi-Square test of independence. LTPA: leisure-time physical activity. The sample size (N=3,819) is the maximum number used in baseline analyses and includes participants who were subsequently randomized to troglitazone treatment, in addition to those randomized to lifestyle, metformin, or placebo. Sample sizes for: short-term weight loss (n=3085); long-term weight loss (n=3015); diabetes risk (n=3234). We include individuals subsequently randomized to troglitazone in the baseline analyses to maximize statistical power. However, these individuals are not included in the prospective analyses as they represent a relatively small subgroup of the DPP population, which is likely underpowered for treatment stratified analyses. Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. a The troglitazone arm was terminated early(11) and, by consequence, only baseline data are used in this paper. NIH-PA Author Manuscript Page 26 NIH-PA Author Manuscript NIH-PA Author Manuscript Table 2 Pan et al. Association between MC4R SNPs with baseline weight (kg) and BMI (kg/m2) (N=3,346–3,356) Weight (kg/allele) Coefficient (SE) G(T) C(T) G(A) C(A) A(G) T(C) C(T) G(C) G(A) C(T) A(T) A(G) A(G) T(C) A(G) T(C) G(T) G(C) T(A) T(C) -0.14 (0.70) 0.838 -0.15 (0.24) 0.52 (1.09) 0.633 0.29 (0.37) 0.429 0.526 0.12 (0.64) 0.854 -0.14 (0.22) 0.510 -0.29 (0.93) 0.752 -0.08 (0.31) 0.805 0.40(0.50) 0.425 0.00 (0.19) 0.989 0.59 (0.59) 0.316 0.13 (0.20) 0.509 -0.01 (0.52) 0.983 -0.02 (0.18) 0.890 0.44 (0.76) 0.568 0.24 (0.26) 0.351 0.88 (0.64) 0.168 0.35 (0.21) 0.102 -0.33 (0.51) 0.510 -0.16 (0.17) 0.340 -0.18 (0.54) 0.732 -0.08 (0.18) 0.651 -0.57 (0.80) 0.480 -0.09 (0.27) 0.747 0.33 (1.41) 0.815 0.07 (0.47) 0.876 0.11 (0.67) 0.874 0.11 (0.23) 0.611 0.10 (0.52) 0.848 -0.01 (0.17) 0.955 -0.19 (0.73) 0.791 -0.00 (0.25) 0.992 0.92 (2.06) 0.654 -0.10 (0.69) 0.882 -1.08 (2.36) 0.648 0.21 (0.80) 0.790 0.80 (1.21) 0.509 0.12 (0.41) 0.766 0.29 (0.94) 0.759 -0.19 (0.32) 0.556 P-value Coefficient (SE) P-value BMI (kg/m2/allele) SNP Minor(major) allele rs1943226 rs11875096 rs1943224 rs7235242 rs11872992 rs8093815 rs17066856 rs17066836 rs1943227 rs1943218 rs17066829 rs9966412 rs17066859 rs9965495 rs12970134 rs17700633 rs11873305 rs8091237 Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. rs17066866 rs7240064 Coefficients, Standard Errors (SE) and P-values correspond to the additive allele effects adjusted for age at randomization, sex and ethnicity. The reported P-values are not adjusted for multiple comparison. NIH-PA Author Manuscript Page 27 NIH-PA Author Manuscript NIH-PA Author Manuscript Table 3 Pan et al. SNP effects on short-term, long-term weight loss and diabetes risk 6-month Weight change (kg/allele) N=3085 Coefficient (SE) G(T) C(T) G(A) C(A) A(G) T(C) C(T) G(C) G(A) C(T) 0.032 0.884 0.207 0.548 0.273 0.738 -0.18 (0.32) 0.15 (0.23) 0.27 (0.25) 0.10 (0.20) 0.20 (0.18) 0.44 (0.27) 0.103 0.265 0.596 0.577 0.521 0.268 0.25 (0.23) 0.260 0.14 (0.18) 0.420 0.038 A(T) A(G) A(G) T(C) A(G) T(C) G(T) G(C) T(A) T(C) -0.08 (0.24) 0.15 (0.14) -0.09 (0.15) 0.17 (0.13) 0.02 (0.13) 0.29 (0.14) 0.39 (0.19) 0.13 (0.20) 0.507 0.05 (0.28) 0.847 -0.12 (0.36) 0.734 -0.10 (0.49) 0.834 0.20 (0.24) 0.392 0.94 (0.83-1.07) 0.84 (0.63-1.11) 0.95 (0.81-1.12) 0.99 (0.89-1.10) 0.98 (0.86-1.11) 0.94 (0.81-1.09) 1.00 (0.91-1.11) 1.02 (0.91-1.14) 0.97 (0.87-1.08) 0.99 (0.83-1.18) 0.99 (0.87-1.12) 0.98 (0.80-1.21) 1.01 (0.88-1.16) 0.13 (0.13) 0.304 0.32 (0.18) 0.081 0.99 (0.90-1.09) -0.11 (0.18) 0.566 -0.18 (0.26) 0.474 1.04 (0.90-1.20) 0.06 (0.53) 0.908 -0.07 (0.73) 0.920 1.28 (0.88-1.86) 0.02 (0.59) 0.968 0.30 (0.82) 0.715 1.18 (0.78-1.79) 0.431 0.194 0.606 0.854 0.375 0.216 0.540 0.869 0.737 0.403 0.980 0.788 0.595 0.903 0.815 0.854 0.875 0.06 (0.31) 0.835 0.30 (0.42) 0.473 0.97 (0.77-1.23) 0.805 0.35 (0.24) 0.144 0.10 (0.33) 0.774 1.00 (0.91-1.11) 0.980 P-value Coefficient (SE) P-value HR (95% CI) P-value 2-year Weight change (kg/allele) N=3015 Diabetes Risk (Hazard Ratio) N=3234 SNP Minor (major) allele rs1943226 rs11875096 rs1943224 rs7235242 rs11872992 rs8093815 rs17066856 rs17066836 rs1943227 rs1943218 rs17066829 rs9966412 rs17066859 rs9965495 rs12970134 rs17700633 rs11873305 rs8091237 Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. rs17066866 rs7240064 All analyses are adjusted for baseline age, sex, ethnicity and treatment assignment. Allele effects are estimated within the pooled sample of three treatment groups, unless the test of treatment*SNP interaction was statistically significant (P<0.05), in which case the cells in the table are left blank and the relevant results are reported in Table 4. NIH-PA Author Manuscript Page 28 NIH-PA Author Manuscript NIH-PA Author Manuscript Table 4 Pan et al. Treatment-specific SNP effects on short-term weight loss and diabetes risk. Lifestyle Coefficient(SE) P-values 1041 C(T) A(G) 0.034 0.016 0.094 0.207 0.266 0.024 P-value P-value 1012 0.513 0.866 P-value 1082 0.514 1.09 (0.92-1.29) 0.309 HR(95% CI) P-value 0.02 (0.60) 0.979 0.24 (0.32) 0.450 Coefficient(SE) 0.64 (0.28) 0.05 (0.45) 0.917 0.32 (0.26) 0.215 -0.36 (0.31) 0.245 A(G) G(C) T(A) 0.006 0.758 P-value 1004 0.081 0.004 P-value 1073 0.054 1.06 (0.89-1.27) HR(95% CI) 0.10 (0.60) 0.20 (0.31) Coefficient(SE) 0.29 (0.26) T(C) Coefficient(SE) 999 A(G) T(A) HR(95% CI) 1079 A(T) 0.80 (0.64-1.00) 2.25 (0.77) -0.75 (0.43) -0.11 (0.34) 1.48 (0.53) 0.54 (0.43) -0.36 (0.32) 0.259 0.40 (0.24) 0.35 (0.39) 0.358 0.71 (0.30) 0.15 (0.32) 0.640 0.54 (0.26) -0.28 (0.25) 0.258 -0.01 (0.33) 0.980 0.50 (0.27) 0.064 -0.33 (0.27) 0.214 1024 1020 P-value Coefficient(SE) P-value Coefficient(SE) Metformin Placebo SNP Minor (major) allele 6m Weight Loss (kg/allele) N rs17066856 rs9966412 rs17066859 rs8091237 rs17066866 rs7240064 2yr Weight Loss (kg/allele) N rs12970134 rs17066866 Diabetes Risk N rs17066829 Obesity (Silver Spring). Author manuscript; available in PMC 2014 May 16. All analyses are adjusted for baseline age, sex, ethnicity and treatment assignment. NIH-PA Author Manuscript Page 29 NIH-PA Author Manuscript NIH-PA Author Manuscript