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1.  Activating germline mutations in STAT3 cause early-onset multi-organ autoimmune disease 
Nature genetics  2014;46(8):812-814.
Monogenic causes of autoimmunity give key insights to the complex regulation of the immune system. We report a new monogenic cause of autoimmunity resulting from de novo germline activating STAT3 mutations in 5 individuals with a spectrum of early-onset autoimmune disease including type 1 diabetes. These findings emphasise the critical role of STAT3 in autoimmune disease and contrast with the germline inactivating STAT3 mutations that result in Hyper IgE syndrome.
doi:10.1038/ng.3040
PMCID: PMC4129488  PMID: 25038750
2.  Phenotypic severity of homozygous GCK mutations causing neonatal or childhood-onset diabetes is primarily mediated through effects on protein stability 
Human molecular genetics  2014;23(24):6432-6440.
Mutations in glucokinase (GCK) cause a spectrum of glycemic disorders. Heterozygous loss-of-function mutations cause mild fasting hyperglycemia irrespective of mutation severity due to compensation from the unaffected allele. Conversely, homozygous loss-of-function mutations cause permanent neonatal diabetes requiring lifelong insulin treatment. This study aimed to determine the relationship between in vitro mutation severity and clinical phenotype in a large international case series of patients with homozygous GCK mutations. Clinical characteristics for 30 patients with diabetes due to homozygous GCK mutations (19 unique mutations, including 16 missense) were compiled and assigned a clinical severity grade (CSG) based on birth weight and age at diagnosis. The majority (28 of 30) of subjects were diagnosed before 9 months, with the remaining two at 9 and 15 years. These are the first two cases of a homozygous GCK mutation diagnosed outside infancy. Recombinant mutant GCK proteins were analyzed for kinetic and thermostability characteristics and assigned a relative activity index (RAI) or relative stability index (RSI) value. Six of 16 missense mutations exhibited severe kinetic defects (RAI ≤ 0.01). There was no correlation between CSG and RAI (r2 = 0.05, P = 0.39), indicating that kinetics alone did not explain the phenotype. Eighty percent of the remaining mutations showed reduced thermostability, the exceptions being the two later-onset mutations which exhibited increased thermostability. Comparison of CSG with RSI detected a highly significant correlation (r2 = 0.74, P = 0.002). We report the largest case series of homozygous GCK mutations to date and demonstrate that they can cause childhood-onset diabetes, with protein instability being the major determinant of mutation severity.
doi:10.1093/hmg/ddu360
PMCID: PMC4240195  PMID: 25015100
4.  Digenic heterozygous HNF1A and HNF4A mutations in two siblings with childhood-onset diabetes 
Pediatric diabetes  2013;14(7):535-538.
Monogenic diabetes due to mutations in the transcription factor genes HNF1A and HNF4A is characterized by islet cell antibody negative, familial diabetes with residual insulin secretion. We report two sisters with childhood onset diabetes who are both heterozygous for the most common mutation in each of two transcription factors, hepatocyte nuclear factor 1A (HNF1A) and hepatocyte nuclear factor 4A (HNF4A). The proband was diagnosed with diabetes at 7 years of age and treated with insulin for 4 years. Her genetic diagnosis resulted in transition to sulfonylureas for one and a half years before insulin therapy was re-initiated due to declining glycemic control. Her sister was diagnosed with diabetes at 14 years of age, treated initially with insulin but has been well controlled on oral sulfonylurea therapy for over two years. Both sisters inherited the HNF4A gene mutation R127W from their mother and the HNF1A gene mutation P291fsinsC (c.872dup) from their father. The father was diagnosed with diabetes at 45 years of age. Their brother is heterozygous for the HNF4A R127W mutation. Both the brother and mother have normal glucose tolerance at the ages of 16 and 46 years, respectively.
Digenic inheritance of HNF1A and HNF4A mutations is very rare and has only been reported in two families where conclusive evidence for the pathogenicity of their mutations was lacking. Follow-up studies in this family co-segregating the two most commonly reported HNF1A/HNF4A mutations will be informative for understanding the effect of digenic inheritance upon phenotypic severity and response to sulfonylurea therapy.
doi:10.1111/pedi.12018
PMCID: PMC4090307  PMID: 23551881
HNF1A; HNF4A; MODY; youth
5.  Identifying Good Responders to Glucose Lowering Therapy in Type 2 Diabetes: Implications for Stratified Medicine 
PLoS ONE  2014;9(10):e111235.
Aims
Defining responders to glucose lowering therapy can be important for both clinical care and for the development of a stratified approach to diabetes management. Response is commonly defined by either HbA1c change after treatment or whether a target HbA1c is achieved. We aimed to determine the extent to which the individuals identified as responders and non-responders to glucose lowering therapy, and their characteristics, depend on the response definition chosen.
Methods
We prospectively studied 230 participants commencing GLP-1 agonist therapy. We assessed participant characteristics at baseline and repeated HbA1c after 3 months treatment. We defined responders (best quartile of response) based on HbA1c change or HbA1c achieved. We assessed the extent to which these methods identified the same individuals and how this affected the baseline characteristics associated with treatment response.
Results
Different definitions of response identified different participants. Only 39% of responders by one definition were also good responders by the other. Characteristics associated with good response depend on the response definition chosen: good response by HbA1c achieved was associated with low baseline HbA1c (p<0.001), high C-peptide (p<0.001) and shorter diabetes duration (p = 0.01) whereas response defined by HbA1c change was associated with high HbA1c (p<0.001) only. We describe a simple novel method of defining treatment response based on a combination of HbA1c change and HbA1c achieved that defines response groups with similar baseline glycaemia.
Conclusions
The outcome of studies aiming to identify predictors of treatment response to glucose lowering therapy may depend on how response is defined. Alternative definitions of response should be considered which minimise influence of baseline glycaemia.
doi:10.1371/journal.pone.0111235
PMCID: PMC4207765  PMID: 25340784
6.  Mendelian Randomization Studies Do Not Support a Causal Role for Reduced Circulating Adiponectin Levels in Insulin Resistance and Type 2 Diabetes 
Yaghootkar, Hanieh | Lamina, Claudia | Scott, Robert A. | Dastani, Zari | Hivert, Marie-France | Warren, Liling L. | Stancáková, Alena | Buxbaum, Sarah G. | Lyytikäinen, Leo-Pekka | Henneman, Peter | Wu, Ying | Cheung, Chloe Y.Y. | Pankow, James S. | Jackson, Anne U. | Gustafsson, Stefan | Zhao, Jing Hua | Ballantyne, Christie M. | Xie, Weijia | Bergman, Richard N. | Boehnke, Michael | el Bouazzaoui, Fatiha | Collins, Francis S. | Dunn, Sandra H. | Dupuis, Josee | Forouhi, Nita G. | Gillson, Christopher | Hattersley, Andrew T. | Hong, Jaeyoung | Kähönen, Mika | Kuusisto, Johanna | Kedenko, Lyudmyla | Kronenberg, Florian | Doria, Alessandro | Assimes, Themistocles L. | Ferrannini, Ele | Hansen, Torben | Hao, Ke | Häring, Hans | Knowles, Joshua W. | Lindgren, Cecilia M. | Nolan, John J. | Paananen, Jussi | Pedersen, Oluf | Quertermous, Thomas | Smith, Ulf | Lehtimäki, Terho | Liu, Ching-Ti | Loos, Ruth J.F. | McCarthy, Mark I. | Morris, Andrew D. | Vasan, Ramachandran S. | Spector, Tim D. | Teslovich, Tanya M. | Tuomilehto, Jaakko | van Dijk, Ko Willems | Viikari, Jorma S. | Zhu, Na | Langenberg, Claudia | Ingelsson, Erik | Semple, Robert K. | Sinaiko, Alan R. | Palmer, Colin N.A. | Walker, Mark | Lam, Karen S.L. | Paulweber, Bernhard | Mohlke, Karen L. | van Duijn, Cornelia | Raitakari, Olli T. | Bidulescu, Aurelian | Wareham, Nick J. | Laakso, Markku | Waterworth, Dawn M. | Lawlor, Debbie A. | Meigs, James B. | Richards, J. Brent | Frayling, Timothy M.
Diabetes  2013;62(10):3589-3598.
Adiponectin is strongly inversely associated with insulin resistance and type 2 diabetes, but its causal role remains controversial. We used a Mendelian randomization approach to test the hypothesis that adiponectin causally influences insulin resistance and type 2 diabetes. We used genetic variants at the ADIPOQ gene as instruments to calculate a regression slope between adiponectin levels and metabolic traits (up to 31,000 individuals) and a combination of instrumental variables and summary statistics–based genetic risk scores to test the associations with gold-standard measures of insulin sensitivity (2,969 individuals) and type 2 diabetes (15,960 case subjects and 64,731 control subjects). In conventional regression analyses, a 1-SD decrease in adiponectin levels was correlated with a 0.31-SD (95% CI 0.26–0.35) increase in fasting insulin, a 0.34-SD (0.30–0.38) decrease in insulin sensitivity, and a type 2 diabetes odds ratio (OR) of 1.75 (1.47–2.13). The instrumental variable analysis revealed no evidence of a causal association between genetically lower circulating adiponectin and higher fasting insulin (0.02 SD; 95% CI −0.07 to 0.11; N = 29,771), nominal evidence of a causal relationship with lower insulin sensitivity (−0.20 SD; 95% CI −0.38 to −0.02; N = 1,860), and no evidence of a relationship with type 2 diabetes (OR 0.94; 95% CI 0.75–1.19; N = 2,777 case subjects and 13,011 control subjects). Using the ADIPOQ summary statistics genetic risk scores, we found no evidence of an association between adiponectin-lowering alleles and insulin sensitivity (effect per weighted adiponectin-lowering allele: −0.03 SD; 95% CI −0.07 to 0.01; N = 2,969) or type 2 diabetes (OR per weighted adiponectin-lowering allele: 0.99; 95% CI 0.95–1.04; 15,960 case subjects vs. 64,731 control subjects). These results do not provide any consistent evidence that interventions aimed at increasing adiponectin levels will improve insulin sensitivity or risk of type 2 diabetes.
doi:10.2337/db13-0128
PMCID: PMC3781444  PMID: 23835345
7.  Neurogenin 3 is important but not essential for pancreatic islet development in humans 
Diabetologia  2014;57(11):2421-2424.
doi:10.1007/s00125-014-3349-y
PMCID: PMC4181041  PMID: 25120094
Diabetes; Enteric anendocrinosis; Islet development; Neonatal diabetes; Neurogenin 3
8.  Recessive mutations in a distal PTF1A enhancer cause isolated pancreatic agenesis 
Nature genetics  2013;46(1):61-64.
The contribution of cis-regulatory mutations to human disease remains poorly understood. Whole genome sequencing can identify all non-coding variants, yet discrimination of causal regulatory mutations represents a formidable challenge. We used epigenomic annotation in hESC-derived embryonic pancreatic progenitor cells to guide the interpretation of whole genome sequences from patients with isolated pancreatic agenesis. This uncovered six different recessive mutations in a previously uncharacterized ~400bp sequence located 25kb downstream of PTF1A (pancreas-specific transcription factor 1a) in ten families with pancreatic agenesis. We show that this region acts as a developmental enhancer of PTF1A and that the mutations abolish enhancer activity. These mutations are the most common cause of isolated pancreatic agenesis. Integrating genome sequencing and epigenomic annotation in a disease-relevant cell type can uncover novel non-coding elements underlying human development and disease.
doi:10.1038/ng.2826
PMCID: PMC4131753  PMID: 24212882
9.  Permanent Neonatal Diabetes Mellitus: Prevalence and Genetic Diagnosis in the SEARCH for Diabetes in Youth Study 
Pediatric diabetes  2012;14(3):174-180.
Background
Neonatal diabetes mellitus (NDM) is defined as diabetes with onset before 6 months of age. Nearly half of individuals with NDM are affected by permanent neonatal diabetes mellitus (PNDM). Mutations in KATP channel genes (KCNJ11, ABCC8) and the insulin gene (INS) are the most common causes of PNDM.
Objective
To estimate the prevalence of PNDM among SEARCH for Diabetes in Youth (SEARCH) study participants (2001-2008) and to identify the genetic mutations causing PNDM.
Methods
SEARCH is a multi-center population-based study of diabetes in youth < 20 years of age. Participants diagnosed with diabetes before 6 months of age were invited for genetic testing for mutations in the KCNJ11, ABCC8 and INS genes.
Results
Of the 15,829 SEARCH participants with diabetes, 39 were diagnosed before 6 months of age. Thirty five of them had PNDM (0.22% of all diabetes cases in SEARCH), 3 had transient neonatal diabetes that had remitted by 18 months and one was unknown. The majority of them (66.7%) had a clinical diagnosis of type1 diabetes by their health care provider. Population prevalence of PNDM in youth <20 years was estimated at 1 in 252,000. Seven participants underwent genetic testing; mutations causing PNDM were identified in five (71%), (two KCNJ11, three INS).
Conclusions
We report the first population-based frequency of PNDM in the US based on the frequency of PNDM in SEARCH. Patients with NDM are often misclassified as having type1 diabetes. Widespread education is essential to encourage appropriate genetic testing and treatment of NDM.
doi:10.1111/pedi.12003
PMCID: PMC4101463  PMID: 23050777
neonatal diabetes; KCNJ11; INS; ABCC8; infant
10.  Using highly sensitive C-reactive protein measurement to diagnose MODY in a family with suspected type 2 diabetes 
BMJ Case Reports  2012;2012:bcr0120125612.
The authors report an adolescent who was found to have diabetes on routine blood testing. The initial diagnosis was type 2 diabetes because she was obese, did not have type 1 diabetes antibodies and both parents had diabetes. Highly sensitive C-reactive protein (hsCRP) was low in the proband and her father (≤0.1 mg/l) indicating that type 2 diabetes was unlikely, and that hepatocyte nuclear factor 1-α-maturity onset diabetes of the young (HNF1A-MODY) was the most likely diagnosis. Following a genetic diagnosis of HNF1A-MODY in the proband and her father, both patients were treated with gliclazide, with improvement in HbA1c. This case highlights the challenges of making a correct diagnosis of MODY in young onset diabetes. The authors report the first case where hsCRP, an easily available biomarker, has been used on an individual level to determine appropriate genetic testing of MODY in a family whose main differential diagnosis was familial type 2 diabetes.
doi:10.1136/bcr.01.2012.5612
PMCID: PMC3416990  PMID: 22787179
11.  Phenotypic severity of homozygous GCK mutations causing neonatal or childhood-onset diabetes is primarily mediated through effects on protein stability 
Human Molecular Genetics  2014;23(24):6432-6440.
Mutations in glucokinase (GCK) cause a spectrum of glycemic disorders. Heterozygous loss-of-function mutations cause mild fasting hyperglycemia irrespective of mutation severity due to compensation from the unaffected allele. Conversely, homozygous loss-of-function mutations cause permanent neonatal diabetes requiring lifelong insulin treatment. This study aimed to determine the relationship between in vitro mutation severity and clinical phenotype in a large international case series of patients with homozygous GCK mutations. Clinical characteristics for 30 patients with diabetes due to homozygous GCK mutations (19 unique mutations, including 16 missense) were compiled and assigned a clinical severity grade (CSG) based on birth weight and age at diagnosis. The majority (28 of 30) of subjects were diagnosed before 9 months, with the remaining two at 9 and 15 years. These are the first two cases of a homozygous GCK mutation diagnosed outside infancy. Recombinant mutant GCK proteins were analyzed for kinetic and thermostability characteristics and assigned a relative activity index (RAI) or relative stability index (RSI) value. Six of 16 missense mutations exhibited severe kinetic defects (RAI ≤ 0.01). There was no correlation between CSG and RAI (r2 = 0.05, P = 0.39), indicating that kinetics alone did not explain the phenotype. Eighty percent of the remaining mutations showed reduced thermostability, the exceptions being the two later-onset mutations which exhibited increased thermostability. Comparison of CSG with RSI detected a highly significant correlation (r2 = 0.74, P = 0.002). We report the largest case series of homozygous GCK mutations to date and demonstrate that they can cause childhood-onset diabetes, with protein instability being the major determinant of mutation severity.
doi:10.1093/hmg/ddu360
PMCID: PMC4240195  PMID: 25015100
13.  GATA6 haploinsufficiency causes pancreatic agenesis in humans 
Nature genetics  2011;44(1):20-22.
Understanding the regulation of pancreatic development is key for efforts to develop new regenerative therapeutic approaches for diabetes. Rare mutations in PDX1 and PTF1A can cause pancreatic agenesis, however, most instances of this disorder are of unknown origin. We report de novo heterozygous inactivating mutations in GATA6 in 15/27 (56%) individuals with pancreatic agenesis. These findings define the most common cause of human pancreatic agenesis and establish a key role for the transcription factor GATA6 in human pancreatic development.
doi:10.1038/ng.1035
PMCID: PMC4062962  PMID: 22158542
14.  A diagnostic approach for defining idiopathic remitting diabetes: a retrospective cohort study 
Background
11 patients were referred to our Molecular Genetics Department at the Royal Devon and Exeter Hospital between 2000-2012 with a physician’s diagnosis of remitting diabetes. Our aim was to identify patients with remitting diabetes whose clinical presentation is not explained by any known aetiology of diabetes.
Methods
We obtained longitudinal clinical data on all 11 patients from the hospital records. All patients were aged between 0.5 and 35 years at diagnosis. We applied clinical criteria derived from the literature to establish 1) definite diabetes, 2) diabetes initially severe-requiring treatment with insulin, 3) remission of diabetes, and 4) exclusion of known causes of remitting diabetes.
Results
10 out of 11 patients had an alternative explanation for their remission or a clear diagnosis was not identified. We identified a single patient with idiopathic remitting diabetes using these criteria. The patient was a white Caucasian female diagnosed aged 15 with symptoms of diabetes, laboratory glucose of 21.2 mmol/L and HbA1c 134 mmol/mol. Her BMI was 23.6 kg/m2. She was treated with basal bolus insulin but discontinued two years after diagnosis due to hypoglycaemia. 13 years post diagnosis, she had a normal oral glucose tolerance test during pregnancy (fasting glucose 4.5 mmol/L, 2 hr glucose 4.8 mmol/L) and an HbA1c of 30 mmol/mol. This patient does not appear to have Type 1 or Type 2 diabetes, and furthermore does not fit into current classifications of diabetes.
Conclusions
Idiopathic remitting diabetes is rare but does exist. Strict clinical criteria are important to ensure patients have a robust clinical diagnosis. Identification of more patients with idiopathic remitting diabetes will enable further study of the clinical course of this syndrome. Applying these strict criteria will allow the identification of patients with remitting diabetes to assess its aetiology.
doi:10.1186/1472-6823-14-45
PMCID: PMC4064804  PMID: 24909320
Diabetes; Remission; Criteria; Diagnosis; Remitting diabetes
15.  Discovery of biomarkers for glycaemic deterioration before and after the onset of type 2 diabetes: rationale and design of the epidemiological studies within the IMI DIRECT Consortium 
Diabetologia  2014;57(6):1132-1142.
Aims/hypothesis
The DIRECT (Diabetes Research on Patient Stratification) Study is part of a European Union Framework 7 Innovative Medicines Initiative project, a joint undertaking between four industry and 21 academic partners throughout Europe. The Consortium aims to discover and validate biomarkers that: (1) predict the rate of glycaemic deterioration before and after type 2 diabetes onset; (2) predict the response to diabetes therapies; and (3) help stratify type 2 diabetes into clearly definable disease subclasses that can be treated more effectively than without stratification. This paper describes two new prospective cohort studies conducted as part of DIRECT.
Methods
Prediabetic participants (target sample size 2,200–2,700) and patients with newly diagnosed type 2 diabetes (target sample size ~1,000) are undergoing detailed metabolic phenotyping at baseline and 18 months and 36 months later. Abdominal, pancreatic and liver fat is assessed using MRI. Insulin secretion and action are assessed using frequently sampled OGTTs in non-diabetic participants, and frequently sampled mixed-meal tolerance tests in patients with type 2 diabetes. Biosamples include venous blood, faeces, urine and nail clippings, which, among other biochemical analyses, will be characterised at genetic, transcriptomic, metabolomic, proteomic and metagenomic levels. Lifestyle is assessed using high-resolution triaxial accelerometry, 24 h diet record, and food habit questionnaires.
Conclusions/interpretation
DIRECT will yield an unprecedented array of biomaterials and data. This resource, available through managed access to scientists within and outside the Consortium, will facilitate the development of new treatments and therapeutic strategies for the prevention and management of type 2 diabetes.
Electronic supplementary material
The online version of this article (doi:10.1007/s00125-014-3216-x) contains peer-reviewed but unedited supplementary material, which is available to authorised users.
doi:10.1007/s00125-014-3216-x
PMCID: PMC4018481  PMID: 24695864
Epigenetic; Gene–environment interaction; Genome; Glycaemic control; Lifestyle; Microbiome; Prediabetes; Proteome; Transcriptome; Type 2 diabetes
16.  GATA6 Mutations Cause a Broad Phenotypic Spectrum of Diabetes From Pancreatic Agenesis to Adult-Onset Diabetes Without Exocrine Insufficiency 
Diabetes  2013;62(3):993-997.
We recently reported de novo GATA6 mutations as the most common cause of pancreatic agenesis, accounting for 15 of 27 (56%) patients with insulin-treated neonatal diabetes and exocrine pancreatic insufficiency requiring enzyme replacement therapy. We investigated the role of GATA6 mutations in 171 subjects with neonatal diabetes of unknown genetic etiology from a cohort of 795 patients with neonatal diabetes. Mutations in known genes had been confirmed in 624 patients (including 15 GATA6 mutations). Sequencing of the remaining 171 patients identified nine new case subjects (24 of 795, 3%). Pancreatic agenesis was present in 21 case subjects (six new); two patients had permanent neonatal diabetes with no enzyme supplementation and one had transient neonatal diabetes. Four parents with heterozygous GATA6 mutations were diagnosed with diabetes outside the neonatal period (12–46 years). Subclinical exocrine insufficiency was demonstrated by low fecal elastase in three of four diabetic patients who did not receive enzyme supplementation. One parent with a mosaic mutation was not diabetic but had a heart malformation. Extrapancreatic features were observed in all 24 probands and three parents, with congenital heart defects most frequent (83%). Heterozygous GATA6 mutations cause a wide spectrum of diabetes manifestations, ranging from pancreatic agenesis to adult-onset diabetes with subclinical or no exocrine insufficiency.
doi:10.2337/db12-0885
PMCID: PMC3581234  PMID: 23223019
17.  Identification of Novel Genetic Loci Associated with Thyroid Peroxidase Antibodies and Clinical Thyroid Disease 
Medici, Marco | Porcu, Eleonora | Pistis, Giorgio | Teumer, Alexander | Brown, Suzanne J. | Jensen, Richard A. | Rawal, Rajesh | Roef, Greet L. | Plantinga, Theo S. | Vermeulen, Sita H. | Lahti, Jari | Simmonds, Matthew J. | Husemoen, Lise Lotte N. | Freathy, Rachel M. | Shields, Beverley M. | Pietzner, Diana | Nagy, Rebecca | Broer, Linda | Chaker, Layal | Korevaar, Tim I. M. | Plia, Maria Grazia | Sala, Cinzia | Völker, Uwe | Richards, J. Brent | Sweep, Fred C. | Gieger, Christian | Corre, Tanguy | Kajantie, Eero | Thuesen, Betina | Taes, Youri E. | Visser, W. Edward | Hattersley, Andrew T. | Kratzsch, Jürgen | Hamilton, Alexander | Li, Wei | Homuth, Georg | Lobina, Monia | Mariotti, Stefano | Soranzo, Nicole | Cocca, Massimiliano | Nauck, Matthias | Spielhagen, Christin | Ross, Alec | Arnold, Alice | van de Bunt, Martijn | Liyanarachchi, Sandya | Heier, Margit | Grabe, Hans Jörgen | Masciullo, Corrado | Galesloot, Tessel E. | Lim, Ee M. | Reischl, Eva | Leedman, Peter J. | Lai, Sandra | Delitala, Alessandro | Bremner, Alexandra P. | Philips, David I. W. | Beilby, John P. | Mulas, Antonella | Vocale, Matteo | Abecasis, Goncalo | Forsen, Tom | James, Alan | Widen, Elisabeth | Hui, Jennie | Prokisch, Holger | Rietzschel, Ernst E. | Palotie, Aarno | Feddema, Peter | Fletcher, Stephen J. | Schramm, Katharina | Rotter, Jerome I. | Kluttig, Alexander | Radke, Dörte | Traglia, Michela | Surdulescu, Gabriela L. | He, Huiling | Franklyn, Jayne A. | Tiller, Daniel | Vaidya, Bijay | de Meyer, Tim | Jørgensen, Torben | Eriksson, Johan G. | O'Leary, Peter C. | Wichmann, Eric | Hermus, Ad R. | Psaty, Bruce M. | Ittermann, Till | Hofman, Albert | Bosi, Emanuele | Schlessinger, David | Wallaschofski, Henri | Pirastu, Nicola | Aulchenko, Yurii S. | de la Chapelle, Albert | Netea-Maier, Romana T. | Gough, Stephen C. L. | Meyer zu Schwabedissen, Henriette | Frayling, Timothy M. | Kaufman, Jean-Marc | Linneberg, Allan | Räikkönen, Katri | Smit, Johannes W. A. | Kiemeney, Lambertus A. | Rivadeneira, Fernando | Uitterlinden, André G. | Walsh, John P. | Meisinger, Christa | den Heijer, Martin | Visser, Theo J. | Spector, Timothy D. | Wilson, Scott G. | Völzke, Henry | Cappola, Anne | Toniolo, Daniela | Sanna, Serena | Naitza, Silvia | Peeters, Robin P.
PLoS Genetics  2014;10(2):e1004123.
Autoimmune thyroid diseases (AITD) are common, affecting 2-5% of the general population. Individuals with positive thyroid peroxidase antibodies (TPOAbs) have an increased risk of autoimmune hypothyroidism (Hashimoto's thyroiditis), as well as autoimmune hyperthyroidism (Graves' disease). As the possible causative genes of TPOAbs and AITD remain largely unknown, we performed GWAS meta-analyses in 18,297 individuals for TPOAb-positivity (1769 TPOAb-positives and 16,528 TPOAb-negatives) and in 12,353 individuals for TPOAb serum levels, with replication in 8,990 individuals. Significant associations (P<5×10−8) were detected at TPO-rs11675434, ATXN2-rs653178, and BACH2-rs10944479 for TPOAb-positivity, and at TPO-rs11675434, MAGI3-rs1230666, and KALRN-rs2010099 for TPOAb levels. Individual and combined effects (genetic risk scores) of these variants on (subclinical) hypo- and hyperthyroidism, goiter and thyroid cancer were studied. Individuals with a high genetic risk score had, besides an increased risk of TPOAb-positivity (OR: 2.18, 95% CI 1.68–2.81, P = 8.1×10−8), a higher risk of increased thyroid-stimulating hormone levels (OR: 1.51, 95% CI 1.26–1.82, P = 2.9×10−6), as well as a decreased risk of goiter (OR: 0.77, 95% CI 0.66–0.89, P = 6.5×10−4). The MAGI3 and BACH2 variants were associated with an increased risk of hyperthyroidism, which was replicated in an independent cohort of patients with Graves' disease (OR: 1.37, 95% CI 1.22–1.54, P = 1.2×10−7 and OR: 1.25, 95% CI 1.12–1.39, P = 6.2×10−5). The MAGI3 variant was also associated with an increased risk of hypothyroidism (OR: 1.57, 95% CI 1.18–2.10, P = 1.9×10−3). This first GWAS meta-analysis for TPOAbs identified five newly associated loci, three of which were also associated with clinical thyroid disease. With these markers we identified a large subgroup in the general population with a substantially increased risk of TPOAbs. The results provide insight into why individuals with thyroid autoimmunity do or do not eventually develop thyroid disease, and these markers may therefore predict which TPOAb-positives are particularly at risk of developing clinical thyroid dysfunction.
Author Summary
Individuals with thyroid peroxidase antibodies (TPOAbs) have an increased risk of autoimmune thyroid diseases (AITD), which are common in the general population and associated with increased cardiovascular, metabolic and psychiatric morbidity and mortality. As the causative genes of TPOAbs and AITD remain largely unknown, we performed a genome-wide scan for TPOAbs in 18,297 individuals, with replication in 8,990 individuals. Significant associations were detected with variants at TPO, ATXN2, BACH2, MAGI3, and KALRN. Individuals carrying multiple risk variants also had a higher risk of increased thyroid-stimulating hormone levels (including subclinical and overt hypothyroidism), and a decreased risk of goiter. The MAGI3 and BACH2 variants were associated with an increased risk of hyperthyroidism, and the MAGI3 variant was also associated with an increased risk of hypothyroidism. This first genome-wide scan for TPOAbs identified five newly associated loci, three of which were also associated with clinical thyroid disease. With these markers we identified a large subgroup in the general population with a substantially increased risk of TPOAbs. These results provide insight into why individuals with thyroid autoimmunity do or do not eventually develop thyroid disease, and these markers may therefore predict which individuals are particularly at risk of developing clinical thyroid dysfunction.
doi:10.1371/journal.pgen.1004123
PMCID: PMC3937134  PMID: 24586183
18.  The HNF4A R76W mutation causes atypical dominant Fanconi syndrome in addition to a β cell phenotype 
Journal of Medical Genetics  2013;51(3):165-169.
Background
Mutation specific effects in monogenic disorders are rare. We describe atypical Fanconi syndrome caused by a specific heterozygous mutation in HNF4A. Heterozygous HNF4A mutations cause a beta cell phenotype of neonatal hyperinsulinism with macrosomia and young onset diabetes. Autosomal dominant idiopathic Fanconi syndrome (a renal proximal tubulopathy) is described but no genetic cause has been defined.
Methods and Results
We report six patients heterozygous for the p.R76W HNF4A mutation who have Fanconi syndrome and nephrocalcinosis in addition to neonatal hyperinsulinism and macrosomia. All six displayed a novel phenotype of proximal tubulopathy, characterised by generalised aminoaciduria, low molecular weight proteinuria, glycosuria, hyperphosphaturia and hypouricaemia, and additional features not seen in Fanconi syndrome: nephrocalcinosis, renal impairment, hypercalciuria with relative hypocalcaemia, and hypermagnesaemia. This was mutation specific, with the renal phenotype not being seen in patients with other HNF4A mutations. In silico modelling shows the R76 residue is directly involved in DNA binding and the R76W mutation reduces DNA binding affinity. The target(s) selectively affected by altered DNA binding of R76W that results in Fanconi syndrome is not known.
Conclusions
The HNF4A R76W mutation is an unusual example of a mutation specific phenotype, with autosomal dominant atypical Fanconi syndrome in addition to the established beta cell phenotype.
doi:10.1136/jmedgenet-2013-102066
PMCID: PMC3932761  PMID: 24285859
Renal Medicine; Calcium and Bone; Clinical Genetics; Diabetes; Metabolic Disorders
19.  Lessons From the Mixed-Meal Tolerance Test 
Diabetes Care  2013;36(2):195-201.
OBJECTIVE
Mixed-meal tolerance test (MMTT) area under the curve C-peptide (AUC CP) is the gold-standard measure of endogenous insulin secretion in type 1 diabetes but is intensive and invasive to perform. The 90-min MMTT-stimulated CP ≥0.2 nmol/L (90CP) is related to improved clinical outcomes, and CP ≥0.1 nmol/L is the equivalent fasting measure (FCP). We assessed whether 90CP or FCP are alternatives to a full MMTT.
RESEARCH DESIGN AND METHODS
CP was measured during 1,334 MMTTs in 421 type 1 diabetes patients aged <18 years at 3, 9, 18, 48, and 72 months duration. We assessed: 1) correlation between mean AUC CP and 90CP or FCP; 2) sensitivity and specificity of 90CP ≥0.2 nmol/L and FCP ≥ 0.1 nmol/L to detect peak CP ≥0.2 nmol/L and the equivalent AUC CP; and 3) how the time taken to reach the CP peak varied with age of diagnosis and diabetes duration.
RESULTS
AUC CP was highly correlated to 90CP (rs = 0.96; P < 0.0001) and strongly correlated to FCP (rs = 0.84; P < 0.0001). AUC CP ≥23 nmol/L/150 min was the equivalent cutoff for peak CP ≥0.2 nmol/L (98% sensitivity/97% specificity). A 90CP ≥0.2 nmol/L correctly classified 96% patients using AUC or peak CP, whereas FCP ≥0.1 nmol/L classified 83 and 85% patients, respectively. There was only a small difference seen between peak and 90CP (median 0.02 nmol/L). The CP peak occurred earlier in patients with longer diabetes duration (6.1 min each 1-year increase in duration) and younger age (2.5 min each 1-year increase).
CONCLUSIONS
90CP is a highly sensitive and specific measure of AUC and peak CP in children and adolescents with type 1 diabetes and offers a practical alternative to a full MMTT.
doi:10.2337/dc12-0836
PMCID: PMC3554273  PMID: 23111058
21.  An in-frame deletion at the polymerase active site of POLD1 causes a multisystem disorder with lipodystrophy 
Nature genetics  2013;45(8):947-950.
DNA polymerase delta, whose catalytic subunit is encoded by POLD1, is responsible for lagging strand DNA synthesis during DNA replication1. It achieves this with high fidelity due to its intrinsic 3′ to 5′ exonuclease activity, which confers proofreading ability. Missense mutations in the exonuclease domain of POLD1 have recently been shown to predispose to colorectal and endometrial cancer2. Here we report a recurring heterozygous single amino acid deletion at the polymerase active site of POLD1 that abolishes DNA polymerase activity but only mildly impairs 3′ to 5′ exonuclease activity. This mutation causes a distinct multisystem disorder that includes subcutaneous lipodystrophy, deafness, mandibular hypoplasia and hypogonadism in males. This suggests that perturbation of function of the ubiquitously expressed POLD1 polymerase has surprisingly tissue-specific effects in man, and argues for an important role for POLD1 function in adipose tissue homeostasis.
doi:10.1038/ng.2670
PMCID: PMC3785143  PMID: 23770608
22.  Analysis of Transcription Factors Key for Mouse Pancreatic Development Establishes NKX2-2 and MNX1 Mutations as Causes of Neonatal Diabetes in Man 
Cell Metabolism  2014;19(1):146-154.
Summary
Understanding transcriptional regulation of pancreatic development is required to advance current efforts in developing beta cell replacement therapies for patients with diabetes. Current knowledge of key transcriptional regulators has predominantly come from mouse studies, with rare, naturally occurring mutations establishing their relevance in man. This study used a combination of homozygosity analysis and Sanger sequencing in 37 consanguineous patients with permanent neonatal diabetes to search for homozygous mutations in 29 transcription factor genes important for murine pancreatic development. We identified homozygous mutations in 7 different genes in 11 unrelated patients and show that NKX2-2 and MNX1 are etiological genes for neonatal diabetes, thus confirming their key role in development of the human pancreas. The similar phenotype of the patients with recessive mutations and mice with inactivation of a transcription factor gene support there being common steps critical for pancreatic development and validate the use of rodent models for beta cell development.
Graphical Abstract
Highlights
•Homozygous mutations in seven pancreatic transcription factors cause neonatal diabetes•Homozygous NKX2-2 and MNX1 mutations were found in five patients•Confirms NKX2-2 and MNX1 are critical for murine and human pancreas development•Similar phenotypes in mouse and man validate models for beta cell development
Analyzing a large collection of consanguineous patients with permanent neonatal diabetes, Flanagan et al. performed a comprehensive search for recessive mutations in transcription factors known to be critical for mouse pancreatic development. They identify seven pancreatic transcription factors that cause neonatal diabetes, including NKX2-2 and MNX1.
doi:10.1016/j.cmet.2013.11.021
PMCID: PMC3887257  PMID: 24411943
24.  Urine C-peptide creatinine ratio can be used to assess insulin resistance and insulin production in people without diabetes: an observational study 
BMJ Open  2013;3(12):e003193.
Objectives
The current assessment of insulin resistance (IR) in epidemiology studies relies on the blood measurement of C-peptide or insulin. A urine C-peptide creatinine ratio (UCPCR) can be posted from home unaided. It is validated against serum measures of the insulin in people with diabetes. We tested whether UCPCR could be a surrogate measure of IR by examining the correlation of UCPCR with serum insulin, C-peptide and HOMA2 (Homeostasis Model Assessment 2)-IR in participants without diabetes and with chronic kidney disease (CKD).
Design
Observational study.
Setting
Single-centre clinical research facility.
Participants
37 healthy volunteers and 30 patients with CKD (glomerular filtration rate 15–60) were recruited.
Primary and secondary endpoints
Serum insulin, C-peptide and glucose at fasting (0), 30, 60, 90 and 120 min were measured during an oral glucose tolerance test (OGTT). Second-void fasting UCPCR and 120 min post-OGTT UCPCR were collected. HOMA2-IR was calculated using fasting insulin and glucose. The associations between UCPCR and serum measures were assessed using Spearman's correlations.
Results
In healthy volunteers, fasting second-void UCPCR strongly correlated with serum insulin (rs=0.69, p<0.0001), C-peptide (rs=0.73, p<0.0001) and HOMA2-IR (rs=−0.69, p<0.0001). 120 min post-OGTT UCPCR correlated strongly with C-peptide and insulin area under the curve. In patients with CKD, UCPCR did not correlate with serum C-peptide, insulin or HOMA2-IR.
Conclusions
In participants with normal renal function, UCPCR may be a simple, practical method for the assessment of IR in epidemiology studies.
doi:10.1136/bmjopen-2013-003193
PMCID: PMC3884748  PMID: 24353253
Diabetes & Endocrinology; Statistics & Research Methods
25.  Parental diabetes and birthweight in 236 030 individuals in the UK Biobank Study 
Background The UK Biobank study provides a unique opportunity to study the causes and consequences of disease. We aimed to use the UK Biobank data to study the well-established, but poorly understood, association between low birthweight and type 2 diabetes.
Methods We used logistic regression to calculate the odds ratio for participants’ risk of type 2 diabetes given a one standard deviation increase in birthweight. To test for an association between parental diabetes and birthweight, we performed linear regression of self-reported parental diabetes status against birthweight. We performed path and mediation analyses to test the hypothesis that birthweight partly mediates the association between parental diabetes and participant type 2 diabetes status.
Results Of the UK Biobank participants, 277 261 reported their birthweight. Of 257 715 individuals of White ethnicity and singleton pregnancies, 6576 had type 2 diabetes, 19 478 reported maternal diabetes (but not paternal), 20 057 reported paternal diabetes (but not maternal) and 2754 participants reported both parents as having diabetes. Lower birthweight was associated with type 2 diabetes in the UK Biobank participants. A one kilogram increase in birthweight was associated with a lower risk of type 2 diabetes (odds ratio: 0.74; 95% CI: 0.71, 0.76; P = 2 × 10−57). Paternal diabetes was associated with lower birthweight (45 g lower; 95% CI: 36, 54; P = 2 × 10−23) relative to individuals with no parental diabetes. Maternal diabetes was associated with higher birthweight (59 g increase; 95% CI: 50, 68; P = 3 × 10−37). Participants’ lower birthweight was a mediator of the association between reported paternal diabetes and participants’ type 2 diabetes status, explaining 1.1% of the association, and participants’ higher birthweight was a mediator of the association between reported maternal diabetes and participants’ type 2 diabetes status, explaining 1.2% of the association.
Conclusions Data from the UK Biobank provides the strongest evidence by far that paternal diabetes is associated with lower birthweight, whereas maternal diabetes is associated with increased birthweight. Our findings with paternal diabetes are consistent with a role for the same genetic factors influencing foetal growth and type 2 diabetes.
doi:10.1093/ije/dyt220
PMCID: PMC3887570  PMID: 24336895
Type 2 diabetes; parental history; birthweight; UK Biobank; genetics

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