The role of diet in the aetiopathogenesis of inflammatory bowel disease

Crohn’s disease and ulcerative colitis, collectively known as IBD, are chronic inflammatory disorders of the gastrointestinal tract. Although the aetiopathogenesis of IBD is largely unknown, it is widely thought that diet has a crucial role in the development and progression of IBD. Indeed, epidemiological and genetic association studies have identified a number of promising dietary and genetic risk factors for IBD. These preliminary studies have led to major interest in investigating the complex interaction between diet, host genetics, the gut microbiota and immune function in the pathogenesis of IBD. In this Review, we discuss the recent epidemiological, gene–environment interaction, microbiome and animal studies that have explored the relationship between diet and the risk of IBD. In addition, we highlight the limitations of these prior studies, in part by explaining their contradictory findings, and review future directions

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

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 x 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% CI0.55-0.74) of African American adults with T2Dto 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.Peer reviewe

Association analyses based on false discovery rate implicate new loci for coronary artery disease

Genome-wide association studies (GWAS) in coronary artery disease (CAD) had identified 66 loci at 'genome-wide significance' (P < 5 × 10 '8) at the time of this analysis, but a much larger number of putative loci at a false discovery rate (FDR) of 5% (refs. 1,2,3,4). Here we leverage an interim release of UK Biobank (UKBB) data to evaluate the validity of the FDR approach. We tested a CAD phenotype inclusive of angina (SOFT; n cases = 10,801) as well as a stricter definition without angina (HARD; n cases = 6,482) and selected cases with the former phenotype to conduct a meta-analysis using the two most recent CAD GWAS. This approach identified 13 new loci at genome-wide significance, 12 of which were on our previous list of loci meeting the 5% FDR threshold, thus providing strong support that the remaining loci identified by FDR represent genuine signals. The 304 independent variants associated at 5% FDR in this study explain 21.2% of CAD heritability and identify 243 loci that implicate pathways in blood vessel morphogenesis as well as lipid metabolism, nitric oxide signaling and inflammation

Publisher Correction:Protein-altering variants associated with body mass index implicate pathways that control energy intake and expenditure in obesity

In the published version of this paper, the name of author Emanuele Di Angelantonio was misspelled. This error has now been corrected in the HTML and PDF versions of the article

Protein-altering variants associated with body mass index implicate pathways that control energy intake and expenditure in obesity (vol 50, pg 26, 2018)

A.P.R. was supported by R01DK089256. A.W.H. is supported by an NHMRC Practitioner Fellowship (APP1103329). A.K.M. received funding from NIH/NIDDK K01DK107836. A.T.H. is a Wellcome Trust Senior Investigator (WT098395) and an NIH Research Senior Investigator. A.P.M. is a Wellcome Trust Senior Fellow in Basic Biomedical Science (WT098017). A.R.W. is supported by the European Research Council (SZ-245 50371-GLUCOSEGENES-FP7-IDEAS-ERC). A.U.J. is supported by the American Heart Association (13POST16500011) and the NIH (R01DK089256, R01DK101855, K99HL130580). B.K. and E.K.S. were supported by the Doris Duke Medical Foundation, the NIH (R01DK106621), the University of Michigan Internal Medicine Department, Division of Gastroenterology, the University of Michigan Biological Sciences Scholars Program and the Central Society for Clinical Research. C.J.W. is supported by the NIH (HL094535, HL109946). D.J.L. is supported by R01HG008983 and R21DA040177. D.R.W. is supported by the Danish Diabetes Academy, which is funded by the Novo Nordisk Foundation. V. Salomaa has been supported by the Finnish Foundation for Cardiovascular Research. F.W.A. is supported by Dekker scholarship–Junior Staff Member 2014T001 Netherlands Heart Foundation and the UCL Hospitals NIHR Biomedical Research Centre. F.D. is supported by the UK MRC (MC_UU_12013/1-9). G.C.-P. received scholarship support from the University of Queensland and QIMR Berghofer. G.L. is funded by the Montreal Heart Institute Foundation and the Canada Research Chair program. H.Y. and T.M.F. are supported by the European Research Council (323195; SZ-245 50371-GLUCOSEGENES-FP7-IDEAS-ERC). I.M.H. is supported by BMBF (01ER1206) and BMBF (01ER1507m), the NIH and the Max Planck Society. J. Haessler was supported by NHLBI R21HL121422. J.N.H. is supported by NIH R01DK075787. K.E.N. was supported by the NIH (R01DK089256, R01HD057194, U01HG007416, R01DK101855) and the American Heart Association (13GRNT16490017). M.A.R. is supported by the Nuffield Department of Clinical Medicine Award, Clarendon Scholarship. M.I.M. is a Wellcome Trust Senior Investigator (WT098381) and an NIH Research Senior Investigator. M.D. is supported by the NCI (R25CA94880, P30CA008748). P.R.N. is supported by the European Research Council (AdG; 293574), the Research Council of Norway, the University of Bergen, the KG Jebsen Foundation and the Helse Vest, Norwegian Diabetes Association. P.T.E. is supported by the NIH (1R01HL092577, R01HL128914, K24HL105780), by an Established Investigator Award from the American Heart Association (13EIA14220013) and by the Foundation Leducq (14CVD01). P.L.A. was supported by NHLBI R21HL121422 and R01DK089256. P.L.H. is supported by the NIH (NS33335, HL57818). R.S.F. is supported by the NIH (T32GM096911). R.J.F.L. is supported by the NIH (R01DK110113, U01HG007417, R01DK101855, R01DK107786). S.A.L. is supported by the NIH (K23HL114724) and a Doris Duke Charitable Foundation Clinical Scientist Development Award. T.D.S. holds an ERC Advanced Principal Investigator award. T.A.M. is supported by an NHMRC Fellowship (APP1042255). T.H.P. received Lundbeck Foundation and Benzon Foundation support. V.T. is supported by a postdoctoral fellowship from the Canadian Institutes of Health Research (CIHR). Z.K. is supported by the Leenaards Foundation, the Swiss National Science Foundation (31003A-143914) and SystemsX.ch (51RTP0_151019). Part of this work was conducted using the UK Biobank resource (project numbers 1251 and 9072)

Protein-altering variants associated with body mass index implicate pathways that control energy intake and expenditure in obesity (vol 50, pg 26, 2017)

An amendment to this paper has been published and can be accessed via a link at the top of the paper