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1.
Hum Mol Genet ; 28(7): 1212-1224, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30624610

RESUMO

Interpretation of genetic association results is difficult because signals often lack biological context. To generate hypotheses of the functional genetic etiology of complex cardiometabolic traits, we estimated the genetically determined component of gene expression from common variants using PrediXcan (1) and determined genes with differential predicted expression by trait. PrediXcan imputes tissue-specific expression levels from genetic variation using variant-level effect on gene expression in transcriptome data. To explore the value of imputed genetically regulated gene expression (GReX) models across different ancestral populations, we evaluated imputed expression levels for predictive accuracy genome-wide in RNA sequence data in samples drawn from European-ancestry and African-ancestry populations and identified substantial predictive power using European-derived models in a non-European target population. We then tested the association of GReX on 15 cardiometabolic traits including blood lipid levels, body mass index, height, blood pressure, fasting glucose and insulin, RR interval, fibrinogen level, factor VII level and white blood cell and platelet counts in 15 755 individuals across three ancestry groups, resulting in 20 novel gene-phenotype associations reaching experiment-wide significance across ancestries. In addition, we identified 18 significant novel gene-phenotype associations in our ancestry-specific analyses. Top associations were assessed for additional support via query of S-PrediXcan (2) results derived from publicly available genome-wide association studies summary data. Collectively, these findings illustrate the utility of transcriptome-based imputation models for discovery of cardiometabolic effect genes in a diverse dataset.


Assuntos
Previsões/métodos , Metaboloma/genética , Metaboloma/fisiologia , Adulto , Idoso , Pressão Sanguínea , Índice de Massa Corporal , Mapeamento Cromossômico/métodos , Grupos Étnicos/genética , Grupo com Ancestrais do Continente Europeu/genética , Feminino , Estudos de Associação Genética/métodos , Estudo de Associação Genômica Ampla/métodos , Humanos , Masculino , Pessoa de Meia-Idade , Herança Multifatorial/genética , Fenótipo , Polimorfismo de Nucleotídeo Único/genética , Transcriptoma/genética
2.
Biointerphases ; 13(3): 03B416, 2018 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-29609468

RESUMO

Femtosecond laser desorption ionization mass spectrometry was used to obtain mass spectrometric (MS) images of lipids in human pancreatic tissue. The resulting MS images were analyzed using multivariate analysis, specifically principal component analysis and maximum a posteriori (MAP) reconstruction. Both analysis methods showed that the MS images can be separated into lipid and non-lipid areas. MAP analysis further indicated that the lipid areas are composed of phosphatidylcholines and fatty acids. However, definitive identification of the lipids cannot be made because none of the intact parent ions of phosphatidylcholine, sphingomyelins, and/or other lipids were observed. The MAP analysis also revealed that the non-lipid areas could be separated into components that are due to the sample chemical treatment and topography.

3.
Am J Respir Cell Mol Biol ; 58(3): 391-401, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29077507

RESUMO

Obstructive sleep apnea (OSA) is a common heritable disorder displaying marked sexual dimorphism in disease prevalence and progression. Previous genetic association studies have identified a few genetic loci associated with OSA and related quantitative traits, but they have only focused on single ethnic groups, and a large proportion of the heritability remains unexplained. The apnea-hypopnea index (AHI) is a commonly used quantitative measure characterizing OSA severity. Because OSA differs by sex, and the pathophysiology of obstructive events differ in rapid eye movement (REM) and non-REM (NREM) sleep, we hypothesized that additional genetic association signals would be identified by analyzing the NREM/REM-specific AHI and by conducting sex-specific analyses in multiethnic samples. We performed genome-wide association tests for up to 19,733 participants of African, Asian, European, and Hispanic/Latino American ancestry in 7 studies. We identified rs12936587 on chromosome 17 as a possible quantitative trait locus for NREM AHI in men (N = 6,737; P = 1.7 × 10-8) but not in women (P = 0.77). The association with NREM AHI was replicated in a physiological research study (N = 67; P = 0.047). This locus overlapping the RAI1 gene and encompassing genes PEMT1, SREBF1, and RASD1 was previously reported to be associated with coronary artery disease, lipid metabolism, and implicated in Potocki-Lupski syndrome and Smith-Magenis syndrome, which are characterized by abnormal sleep phenotypes. We also identified gene-by-sex interactions in suggestive association regions, suggesting that genetic variants for AHI appear to vary by sex, consistent with the clinical observations of strong sexual dimorphism.


Assuntos
Estudo de Associação Genômica Ampla , Locos de Características Quantitativas/genética , Apneia Obstrutiva do Sono/genética , Sono REM/fisiologia , Fatores de Transcrição/genética , Adulto , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Fosfatidiletanolamina N-Metiltransferase/genética , Caracteres Sexuais , Proteína de Ligação a Elemento Regulador de Esterol 1/genética , Proteínas ras/genética
4.
Diabetologia ; 60(8): 1423-1431, 2017 08.
Artigo em Inglês | MEDLINE | ID: mdl-28478482

RESUMO

AIMS/HYPOTHESIS: Heterozygous mutations in the insulin gene that affect proinsulin biosynthesis and folding are associated with a spectrum of diabetes phenotypes, from permanent neonatal diabetes to MODY. In vivo studies of these mutations may lead to a better understanding of insulin mutation-associated diabetes and point to the best treatment strategy. We studied an 18-year-old woman with MODY heterozygous for the insulin mutation p.R46Q (GlnB22-insulin), measuring the secretion of mutant and wild-type insulin by LC-MS. The clinical study was combined with in vitro studies of the synthesis and secretion of p.R46Q-insulin in rat INS-1 insulinoma cells. METHODS: We performed a standard 75 g OGTT in the 18-year-old woman and measured plasma glucose and serum insulin (wild-type insulin and GlnB22-insulin), C-peptide, proinsulin, glucagon and amylin. The affinity of GlnB22-insulin was tested on human insulin receptors expressed in baby hamster kidney (BHK) cells. We also examined the subcellular localisation, secretion and impact on cellular stress markers of p.R46Q-insulin in INS-1 cells. RESULTS: Plasma GlnB22-insulin concentrations were 1.5 times higher than wild-type insulin at all time points during the OGTT. The insulin-receptor affinity of GlnB22-insulin was 57% of that of wild-type insulin. Expression of p.R46Q-insulin in INS-1 cells was associated with decreased insulin secretion, but not induction of endoplasmic reticulum stress. CONCLUSIONS/INTERPRETATION: The results show that beta cells can process and secrete GlnB22-insulin both in vivo and in vitro. Our combined approach of immunoprecipitation and LC-MS to measure mutant and wild-type insulin may be useful for the study of other mutant insulin proteins. The ability to process and secrete a mutant protein may predict a more benign course of insulin mutation-related diabetes. Diabetes develops when the beta cell is stressed because of increased demand for insulin, as observed in individuals with other insulin mutations that affect the processing of proinsulin to insulin or mutations that reduce the affinity for the insulin receptor.


Assuntos
Diabetes Mellitus/genética , Insulina/genética , Adolescente , Animais , Western Blotting , Peptídeo C/metabolismo , Linhagem Celular , Cricetinae , Feminino , Glucagon/metabolismo , Humanos , Insulina/metabolismo , Polipeptídeo Amiloide das Ilhotas Pancreáticas/metabolismo , Proinsulina/metabolismo , Ratos , Receptor de Insulina/metabolismo
5.
Cardiovasc Diabetol ; 15: 86, 2016 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-27266869

RESUMO

BACKGROUND: There is an increasing appreciation for a series of less traditional risk factors that should not be ignored when considering type 2 diabetes, obesity, hypertension, and cardiovascular disease. These include aortic stiffness, cardiac structure, impaired endothelial function and obstructive sleep apnea. They are associated to varying degrees with each disease categorization and with each other. It is not clear whether they represent additional complications, concomitants or antecedents of disease. Starr County, Texas, with its predominantly Mexican American population has been shown previously to bear a disproportionate burden of the major disease categories, but little is known about the distribution of these less traditional factors. METHODS: Type 2 diabetes, obesity and hypertension frequencies were determined through a systematic survey of Starr County conducted from 2002 to 2006. Individuals from this examination and an enriched set with type 2 diabetes were re-examined from 2010 to 2014 including assessment of cardiac structure, sleep apnea, endothelial function and aortic stiffness. Individual and combined frequencies of these inter-related (i.e., axis) conditions were estimated and associations evaluated. RESULTS: Household screening of 5230 individuals aged 20 years and above followed by direct physical assessment of 1610 identified 23.7 % of men and 26.7 % of women with type 2 diabetes, 46.2 and 49.5 % of men and women, respectively with obesity and 32.1 and 32.4 % with hypertension. Evaluation of pulse wave velocity, left ventricular mass, endothelial function and sleep apnea identified 22.3, 12.7, 48.6 and 45.2 % of men as having "at risk" values for each condition, respectively. Corresponding numbers in women were 16.0, 17.9, 23.6 and 28.8 %. Cumulatively, 88 % of the population has one or more of these while 50 % have three or more. CONCLUSIONS: The full axis of conditions is high among Mexican Americans in Starr County, Texas. Individual and joint patterns suggest a genesis well before overt disease. Whether they are all mediated by common underlying factors or whether there exist multiple mechanisms remains to be seen.


Assuntos
Aorta/fisiopatologia , Diabetes Mellitus Tipo 2/complicações , Hipertensão/complicações , Hipertrofia Ventricular Esquerda/complicações , Obesidade/complicações , Síndromes da Apneia do Sono/complicações , Apneia Obstrutiva do Sono/complicações , Adulto , Idoso , Idoso de 80 Anos ou mais , Diabetes Mellitus Tipo 2/fisiopatologia , Feminino , Hispano-Americanos , Humanos , Hipertensão/fisiopatologia , Hipertrofia Ventricular Esquerda/fisiopatologia , Masculino , Americanos Mexicanos , Pessoa de Meia-Idade , Obesidade/fisiopatologia , Análise de Onda de Pulso , Síndromes da Apneia do Sono/fisiopatologia , Apneia Obstrutiva do Sono/fisiopatologia , Texas , Rigidez Vascular/fisiologia , Adulto Jovem
6.
Am J Respir Crit Care Med ; 194(7): 886-897, 2016 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-26977737

RESUMO

RATIONALE: Obstructive sleep apnea is a common disorder associated with increased risk for cardiovascular disease, diabetes, and premature mortality. Although there is strong clinical and epidemiologic evidence supporting the importance of genetic factors in influencing obstructive sleep apnea, its genetic basis is still largely unknown. Prior genetic studies focused on traits defined using the apnea-hypopnea index, which contains limited information on potentially important genetically determined physiologic factors, such as propensity for hypoxemia and respiratory arousability. OBJECTIVES: To define novel obstructive sleep apnea genetic risk loci for obstructive sleep apnea, we conducted genome-wide association studies of quantitative traits in Hispanic/Latino Americans from three cohorts. METHODS: Genome-wide data from as many as 12,558 participants in the Hispanic Community Health Study/Study of Latinos, Multi-Ethnic Study of Atherosclerosis, and Starr County Health Studies population-based cohorts were metaanalyzed for association with the apnea-hypopnea index, average oxygen saturation during sleep, and average respiratory event duration. MEASUREMENTS AND MAIN RESULTS: Two novel loci were identified at genome-level significance (rs11691765, GPR83, P = 1.90 × 10-8 for the apnea-hypopnea index, and rs35424364; C6ORF183/CCDC162P, P = 4.88 × 10-8 for respiratory event duration) and seven additional loci were identified with suggestive significance (P < 5 × 10-7). Secondary sex-stratified analyses also identified one significant and several suggestive associations. Multiple loci overlapped genes with biologic plausibility. CONCLUSIONS: These are the first genome-level significant findings reported for obstructive sleep apnea-related physiologic traits in any population. These findings identify novel associations in inflammatory, hypoxia signaling, and sleep pathways.

7.
Hum Mol Genet ; 25(10): 2070-2081, 2016 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-26911676

RESUMO

To gain insight into potential regulatory mechanisms through which the effects of variants at four established type 2 diabetes (T2D) susceptibility loci (CDKAL1, CDKN2A-B, IGF2BP2 and KCNQ1) are mediated, we undertook transancestral fine-mapping in 22 086 cases and 42 539 controls of East Asian, European, South Asian, African American and Mexican American descent. Through high-density imputation and conditional analyses, we identified seven distinct association signals at these four loci, each with allelic effects on T2D susceptibility that were homogenous across ancestry groups. By leveraging differences in the structure of linkage disequilibrium between diverse populations, and increased sample size, we localised the variants most likely to drive each distinct association signal. We demonstrated that integration of these genetic fine-mapping data with genomic annotation can highlight potential causal regulatory elements in T2D-relevant tissues. These analyses provide insight into the mechanisms through which T2D association signals are mediated, and suggest future routes to understanding the biology of specific disease susceptibility loci.


Assuntos
Mapeamento Cromossômico , Diabetes Mellitus Tipo 2/genética , Estudos de Associação Genética , Predisposição Genética para Doença , Afro-Americanos/genética , Alelos , Grupo com Ancestrais do Continente Asiático/genética , Inibidor de Quinase Dependente de Ciclina p18/genética , Diabetes Mellitus Tipo 2/patologia , Grupo com Ancestrais do Continente Europeu/genética , Feminino , Humanos , Canal de Potássio KCNQ1/genética , Desequilíbrio de Ligação , Masculino , Polimorfismo de Nucleotídeo Único , Proteínas de Ligação a RNA/genética , Elementos Reguladores de Transcrição/genética , tRNA Metiltransferases/genética
8.
PLoS One ; 10(11): e0142130, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26569114

RESUMO

Staphylococcus aureus is the number one cause of hospital-acquired infections. Understanding host pathogen interactions is paramount to the development of more effective treatment and prevention strategies. Therefore, whole exome sequence and chip-based genotype data were used to conduct rare variant and genome-wide association analyses in a Mexican-American cohort from Starr County, Texas to identify genes and variants associated with S. aureus nasal carriage. Unlike most studies of S. aureus that are based on hospitalized populations, this study used a representative community sample. Two nasal swabs were collected from participants (n = 858) 11-17 days apart between October 2009 and December 2013, screened for the presence of S. aureus, and then classified as either persistent, intermittent, or non-carriers. The chip-based and exome sequence-based single variant association analyses identified 1 genome-wide significant region (KAT2B) for intermittent and 11 regions suggestively associated with persistent or intermittent S. aureus carriage. We also report top findings from gene-based burden analyses of rare functional variation. Notably, we observed marked differences between signals associated with persistent and intermittent carriage. In single variant analyses of persistent carriage, 7 of 9 genes in suggestively associated regions and all 5 top gene-based findings are associated with cell growth or tight junction integrity or are structural constituents of the cytoskeleton, suggesting that variation in genes associated with persistent carriage impact cellular integrity and morphology.


Assuntos
Portador Sadio , Estudo de Associação Genômica Ampla , Nariz/microbiologia , Infecções Estafilocócicas/genética , Adulto , Idoso , Estudos de Coortes , Exoma , Éxons , Feminino , Variação Genética , Genótipo , Humanos , Inflamação , Masculino , Americanos Mexicanos , Pessoa de Meia-Idade , Fenótipo , Polimorfismo de Nucleotídeo Único , Análise de Regressão , Infecções Estafilocócicas/etnologia , Staphylococcus aureus , Texas , Fatores de Transcrição de p300-CBP/genética
9.
J Med Genet ; 52(9): 612-6, 2015 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-26101329

RESUMO

BACKGROUND: Diabetes in neonates usually has a monogenic aetiology; however, the cause remains unknown in 20-30%. Heterozygous INS mutations represent one of the most common gene causes of neonatal diabetes mellitus. METHODS: Clinical and functional characterisation of a novel homozygous intronic mutation (c.187+241G>A) in the insulin gene in a child identified through the Monogenic Diabetes Registry (http://monogenicdiabetes.uchicago.edu). RESULTS: The proband had insulin-requiring diabetes from birth. Ultrasonography revealed a structurally normal pancreas and C-peptide was undetectable despite readily detectable amylin, suggesting the presence of dysfunctional ß cells. Whole-exome sequencing revealed the novel mutation. In silico analysis predicted a mutant mRNA product resulting from preferential recognition of a newly created splice site. Wild-type and mutant human insulin gene constructs were derived and transiently expressed in INS-1 cells. We confirmed the predicted transcript and found an additional transcript created via an ectopic splice acceptor site. CONCLUSIONS: Dominant INS mutations cause diabetes via a mutated translational product causing endoplasmic reticulum stress. We describe a novel mechanism of diabetes, without ß cell death, due to creation of two unstable mutant transcripts predicted to undergo nonsense and non-stop-mediated decay, respectively. Our discovery may have broader implications for those with insulin deficiency later in life.


Assuntos
Diabetes Mellitus/genética , Insulina Regular Humana/genética , Íntrons , Mutação , Diabetes Mellitus/etiologia , Humanos , Lactente , Análise de Sequência de DNA
10.
Am J Physiol Endocrinol Metab ; 308(11): E978-89, 2015 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-25852003

RESUMO

Nonobese diabetic (NOD) mice are a commonly used model of type 1 diabetes (T1D). However, not all animals will develop overt diabetes despite undergoing similar autoimmune insult. In this study, a comprehensive metabolomic approach, consisting of gas chromatography time-of-flight (GC-TOF) mass spectrometry (MS), ultra-high-performance liquid chromatography-accurate mass quadruple time-of-flight (UHPLC-qTOF) MS and targeted UHPLC-tandem mass spectrometry-based methodologies, was used to capture metabolic alterations in the metabolome and lipidome of plasma from NOD mice progressing or not progressing to T1D. Using this multi-platform approach, we identified >1,000 circulating lipids and metabolites in male and female progressor and nonprogressor animals (n = 71). Statistical and multivariate analyses were used to identify age- and sex-independent metabolic markers, which best differentiated metabolic profiles of progressors and nonprogressors. Key T1D-associated perturbations were related with 1) increases in oxidation products glucono-δ-lactone and galactonic acid and reductions in cysteine, methionine and threonic acid, suggesting increased oxidative stress; 2) reductions in circulating polyunsaturated fatty acids and lipid signaling mediators, most notably arachidonic acid (AA) and AA-derived eicosanoids, implying impaired states of systemic inflammation; 3) elevations in circulating triacylglyercides reflective of hypertriglyceridemia; and 4) reductions in major structural lipids, most notably lysophosphatidylcholines and phosphatidylcholines. Taken together, our results highlight the systemic perturbations that accompany a loss of glycemic control and development of overt T1D.


Assuntos
Diabetes Mellitus Experimental/metabolismo , Hipertrigliceridemia/metabolismo , Inflamação/metabolismo , Metaboloma , Estresse Oxidativo/fisiologia , Animais , Diabetes Mellitus Experimental/complicações , Diabetes Mellitus Tipo 1/metabolismo , Diabetes Mellitus Tipo 1/patologia , Regulação para Baixo , Feminino , Hipertrigliceridemia/complicações , Inflamação/complicações , Masculino , Camundongos , Camundongos Endogâmicos NOD , Regulação para Cima
11.
PLoS Genet ; 11(1): e1004876, 2015 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-25625282

RESUMO

Genome wide association studies (GWAS) for fasting glucose (FG) and insulin (FI) have identified common variant signals which explain 4.8% and 1.2% of trait variance, respectively. It is hypothesized that low-frequency and rare variants could contribute substantially to unexplained genetic variance. To test this, we analyzed exome-array data from up to 33,231 non-diabetic individuals of European ancestry. We found exome-wide significant (P<5×10-7) evidence for two loci not previously highlighted by common variant GWAS: GLP1R (p.Ala316Thr, minor allele frequency (MAF)=1.5%) influencing FG levels, and URB2 (p.Glu594Val, MAF = 0.1%) influencing FI levels. Coding variant associations can highlight potential effector genes at (non-coding) GWAS signals. At the G6PC2/ABCB11 locus, we identified multiple coding variants in G6PC2 (p.Val219Leu, p.His177Tyr, and p.Tyr207Ser) influencing FG levels, conditionally independent of each other and the non-coding GWAS signal. In vitro assays demonstrate that these associated coding alleles result in reduced protein abundance via proteasomal degradation, establishing G6PC2 as an effector gene at this locus. Reconciliation of single-variant associations and functional effects was only possible when haplotype phase was considered. In contrast to earlier reports suggesting that, paradoxically, glucose-raising alleles at this locus are protective against type 2 diabetes (T2D), the p.Val219Leu G6PC2 variant displayed a modest but directionally consistent association with T2D risk. Coding variant associations for glycemic traits in GWAS signals highlight PCSK1, RREB1, and ZHX3 as likely effector transcripts. These coding variant association signals do not have a major impact on the trait variance explained, but they do provide valuable biological insights.


Assuntos
Glicemia/genética , Diabetes Mellitus Tipo 2/genética , Glucose-6-Fosfatase/genética , Insulina/sangue , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/patologia , Exoma/genética , Frequência do Gene , Estudo de Associação Genômica Ampla , Receptor do Peptídeo Semelhante ao Glucagon 1 , Índice Glicêmico/genética , Humanos , Insulina/genética , Polimorfismo de Nucleotídeo Único , Receptores de Glucagon/genética
12.
Hum Mol Genet ; 24(6): 1646-54, 2015 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-25398947

RESUMO

Non-coding variation within TCF7L2 remains the strongest genetic determinant of type 2 diabetes risk in humans. A considerable effort has been placed in understanding the functional roles of TCF7L2 in pancreatic beta cells, despite evidence of TCF7L2 expression in various peripheral tissues important in glucose homeostasis. Here, we use a humanized mouse model overexpressing Tcf7l2, resulting in glucose intolerance, to infer the contribution of Tcf7l2 overexpression in beta cells and in other tissues to the metabolic phenotypes displayed by these mice. Restoring Tcf7l2 expression specifically in beta cells to endogenous levels, in face of its overexpression elsewhere, results in impaired insulin secretion, reduced beta cell number and islet area, corroborating data obtained in humans showing similar phenotypes as a result of manipulations leading to Tcf7l2 loss of function. Interestingly, the persistent overexpression of Tcf7l2 in non-pancreatic tissues results in a significant worsening in glucose tolerance in vivo, indicating that Tcf7l2 overexpression in beta cells does not account for the glucose intolerance in the Tcf7l2 overexpression mouse model. Collectively, these data posit that Tcf7l2 plays key roles in glucose metabolism through actions beyond pancreatic beta cells, and further points to functionally opposing cell-type specific effects for Tcf7l2 on the maintenance of balanced glucose metabolism, thereby urging a careful examination of its role in non-pancreatic tissues as well as its composite metabolic effects across distinct tissues. Uncovering these roles may lead to new therapeutic targets for type 2 diabetes.


Assuntos
Diabetes Mellitus Tipo 2/genética , Intolerância à Glucose/genética , Glucose/metabolismo , Proteína 2 Semelhante ao Fator 7 de Transcrição/genética , Animais , Modelos Animais de Doenças , Expressão Gênica , Humanos , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Masculino , Camundongos , Camundongos Transgênicos , Regulação para Cima
13.
JAMA ; 311(22): 2305-14, 2014 Jun 11.
Artigo em Inglês | MEDLINE | ID: mdl-24915262

RESUMO

IMPORTANCE: Latino populations have one of the highest prevalences of type 2 diabetes worldwide. OBJECTIVES: To investigate the association between rare protein-coding genetic variants and prevalence of type 2 diabetes in a large Latino population and to explore potential molecular and physiological mechanisms for the observed relationships. DESIGN, SETTING, AND PARTICIPANTS: Whole-exome sequencing was performed on DNA samples from 3756 Mexican and US Latino individuals (1794 with type 2 diabetes and 1962 without diabetes) recruited from 1993 to 2013. One variant was further tested for allele frequency and association with type 2 diabetes in large multiethnic data sets of 14,276 participants and characterized in experimental assays. MAIN OUTCOME AND MEASURES: Prevalence of type 2 diabetes. Secondary outcomes included age of onset, body mass index, and effect on protein function. RESULTS: A single rare missense variant (c.1522G>A [p.E508K]) was associated with type 2 diabetes prevalence (odds ratio [OR], 5.48; 95% CI, 2.83-10.61; P = 4.4 × 10(-7)) in hepatocyte nuclear factor 1-α (HNF1A), the gene responsible for maturity onset diabetes of the young type 3 (MODY3). This variant was observed in 0.36% of participants without type 2 diabetes and 2.1% of participants with it. In multiethnic replication data sets, the p.E508K variant was seen only in Latino patients (n = 1443 with type 2 diabetes and 1673 without it) and was associated with type 2 diabetes (OR, 4.16; 95% CI, 1.75-9.92; P = .0013). In experimental assays, HNF-1A protein encoding the p.E508K mutant demonstrated reduced transactivation activity of its target promoter compared with a wild-type protein. In our data, carriers and noncarriers of the p.E508K mutation with type 2 diabetes had no significant differences in compared clinical characteristics, including age at onset. The mean (SD) age for carriers was 45.3 years (11.2) vs 47.5 years (11.5) for noncarriers (P = .49) and the mean (SD) BMI for carriers was 28.2 (5.5) vs 29.3 (5.3) for noncarriers (P = .19). CONCLUSIONS AND RELEVANCE: Using whole-exome sequencing, we identified a single low-frequency variant in the MODY3-causing gene HNF1A that is associated with type 2 diabetes in Latino populations and may affect protein function. This finding may have implications for screening and therapeutic modification in this population, but additional studies are required.


Assuntos
Diabetes Mellitus Tipo 2/genética , Fator 1-alfa Nuclear de Hepatócito/genética , Adulto , Idade de Início , Idoso , Feminino , Genótipo , Hispano-Americanos/genética , Humanos , Masculino , México , Pessoa de Meia-Idade , Mutação de Sentido Incorreto , Análise de Sequência de DNA , Estados Unidos
14.
Diabetes ; 63(8): 2744-50, 2014 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-24658302

RESUMO

Mutations in pancreatic duodenal homeobox-1 (PDX1) are associated with diabetes in humans. Pdx1-haploinsufficient mice develop diabetes due to an increase in ß-cell death leading to reduced ß-cell mass. For definition of the molecular link between Pdx1 deficiency and ß-cell death, Pdx1-haploinsufficient mice in which the genes for the BH3-only molecules Bim and Puma had been ablated were studied on a high-fat diet. Compared with Pdx1(+/-) mice, animals haploinsufficient for both Pdx1 and Bim or Puma genes showed improved glucose tolerance, enhanced ß-cell mass, and reduction in the number of TUNEL-positive cells in islets. These results suggest that Bim and Puma ablation improves ß-cell survival in Pdx1(+/-) mice. For exploration of the mechanisms responsible for these findings, Pdx1 gene expression was knocked down in mouse MIN6 insulinoma cells resulting in apoptotic cell death that was found to be associated with increased expression of BH3-only molecules Bim and Puma. If the upregulation of Bim and Puma that occurs during Pdx1 suppression was prevented, apoptotic ß-cell death was reduced in vitro. These results suggest that Bim and Puma play an important role in ß-cell apoptosis in Pdx1-deficient diabetes.


Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Proteínas de Homeodomínio/metabolismo , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/metabolismo , Proteínas de Membrana/metabolismo , Proteínas Proto-Oncogênicas/metabolismo , Transativadores/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Animais , Apoptose , Proteínas Reguladoras de Apoptose/genética , Proteína 11 Semelhante a Bcl-2 , Linhagem Celular , Técnicas de Silenciamento de Genes , Haplótipos , Proteínas de Homeodomínio/genética , Lentivirus , Proteínas de Membrana/genética , Camundongos , Proteínas Proto-Oncogênicas/genética , Interferência de RNA , RNA Mensageiro/genética , RNA Mensageiro/metabolismo , RNA Interferente Pequeno , Transativadores/genética , Transcriptoma , Proteínas Supressoras de Tumor/genética , Regulação para Cima
15.
Nat Genet ; 46(3): 234-44, 2014 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-24509480

RESUMO

To further understanding of the genetic basis of type 2 diabetes (T2D) susceptibility, we aggregated published meta-analyses of genome-wide association studies (GWAS), including 26,488 cases and 83,964 controls of European, east Asian, south Asian and Mexican and Mexican American ancestry. We observed a significant excess in the directional consistency of T2D risk alleles across ancestry groups, even at SNPs demonstrating only weak evidence of association. By following up the strongest signals of association from the trans-ethnic meta-analysis in an additional 21,491 cases and 55,647 controls of European ancestry, we identified seven new T2D susceptibility loci. Furthermore, we observed considerable improvements in the fine-mapping resolution of common variant association signals at several T2D susceptibility loci. These observations highlight the benefits of trans-ethnic GWAS for the discovery and characterization of complex trait loci and emphasize an exciting opportunity to extend insight into the genetic architecture and pathogenesis of human diseases across populations of diverse ancestry.


Assuntos
Diabetes Mellitus Tipo 2/genética , Alelos , Grupo com Ancestrais do Continente Asiático/genética , Estudos de Casos e Controles , Grupo com Ancestrais do Continente Europeu/genética , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Hispano-Americanos/genética , Humanos , Polimorfismo de Nucleotídeo Único , Fatores de Risco
16.
Genetics ; 196(2): 539-55, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24281154

RESUMO

Drosophila melanogaster has been widely used as a model of human Mendelian disease, but its value in modeling complex disease has received little attention. Fly models of complex disease would enable high-resolution mapping of disease-modifying loci and the identification of novel targets for therapeutic intervention. Here, we describe a fly model of permanent neonatal diabetes mellitus and explore the complexity of this model. The approach involves the transgenic expression of a misfolded mutant of human preproinsulin, hINS(C96Y), which is a cause of permanent neonatal diabetes. When expressed in fly imaginal discs, hINS(C96Y) causes a reduction of adult structures, including the eye, wing, and notum. Eye imaginal discs exhibit defects in both the structure and the arrangement of ommatidia. In the wing, expression of hINS(C96Y) leads to ectopic expression of veins and mechano-sensory organs, indicating disruption of wild-type signaling processes regulating cell fates. These readily measurable "disease" phenotypes are sensitive to temperature, gene dose, and sex. Mutant (but not wild-type) proinsulin expression in the eye imaginal disc induces IRE1-mediated XBP1 alternative splicing, a signal for endoplasmic reticulum stress response activation, and produces global change in gene expression. Mutant hINS transgene tester strains, when crossed to stocks from the Drosophila Genetic Reference Panel, produce F1 adults with a continuous range of disease phenotypes and large broad-sense heritability. Surprisingly, the severity of mutant hINS-induced disease in the eye is not correlated with that in the notum in these crosses, nor with eye reduction phenotypes caused by the expression of two dominant eye mutants acting in two different eye development pathways, Drop (Dr) or Lobe (L), when crossed into the same genetic backgrounds. The tissue specificity of genetic variability for mutant hINS-induced disease has, therefore, its own distinct signature. The genetic dominance of disease-specific phenotypic variability in our model of misfolded human proinsulin makes this approach amenable to genome-wide association study in a simple F1 screen of natural variation.


Assuntos
Diabetes Mellitus/genética , Proinsulina/genética , Animais , Animais Geneticamente Modificados , Análise por Conglomerados , Modelos Animais de Doenças , Drosophila melanogaster , Olho/metabolismo , Feminino , Dosagem de Genes , Perfilação da Expressão Gênica , Humanos , Masculino , Mutação , Fenótipo , Proinsulina/química , Dobramento de Proteína , Característica Quantitativa Herdável , Transcriptoma , Transgenes , Asas de Animais/metabolismo
17.
Genetics ; 196(2): 557-67, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24281155

RESUMO

The identification and validation of gene-gene interactions is a major challenge in human studies. Here, we explore an approach for studying epistasis in humans using a Drosophila melanogaster model of neonatal diabetes mellitus. Expression of the mutant preproinsulin (hINS(C96Y)) in the eye imaginal disc mimics the human disease: it activates conserved stress-response pathways and leads to cell death (reduction in eye area). Dominant-acting variants in wild-derived inbred lines from the Drosophila Genetics Reference Panel produce a continuous, highly heritable distribution of eye-degeneration phenotypes in a hINS(C96Y) background. A genome-wide association study (GWAS) in 154 sequenced lines identified a sharp peak on chromosome 3L, which mapped to a 400-bp linkage block within an intron of the gene sulfateless (sfl). RNAi knockdown of sfl enhanced the eye-degeneration phenotype in a mutant-hINS-dependent manner. RNAi against two additional genes in the heparan sulfate (HS) biosynthetic pathway (ttv and botv), in which sfl acts, also modified the eye phenotype in a hINS(C96Y)-dependent manner, strongly suggesting a novel link between HS-modified proteins and cellular responses to misfolded proteins. Finally, we evaluated allele-specific expression difference between the two major sfl-intronic haplotypes in heterozygtes. The results showed significant heterogeneity in marker-associated gene expression, thereby leaving the causal mutation(s) and its mechanism unidentified. In conclusion, the ability to create a model of human genetic disease, map a QTL by GWAS to a specific gene, and validate its contribution to disease with available genetic resources and the potential to experimentally link the variant to a molecular mechanism demonstrate the many advantages Drosophila holds in determining the genetic underpinnings of human disease.


Assuntos
Diabetes Mellitus/genética , Variação Genética , Proinsulina/genética , Alelos , Animais , Animais Geneticamente Modificados , Diabetes Mellitus/metabolismo , Modelos Animais de Doenças , Proteínas de Drosophila/química , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster , Epistasia Genética , Olho/metabolismo , Olho/patologia , Feminino , Expressão Gênica , Técnicas de Silenciamento de Genes , Estudo de Associação Genômica Ampla , Heparitina Sulfato/biossíntese , Humanos , Íntrons , Masculino , Mutação , Fenótipo , Proinsulina/química , Dobramento de Proteína , Interferência de RNA , Sulfotransferases/química , Sulfotransferases/genética , Sulfotransferases/metabolismo
18.
Diabetes Care ; 37(1): 202-9, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24026547

RESUMO

OBJECTIVE To evaluate the cost-effectiveness of a genetic testing policy for HNF1A-, HNF4A-, and GCK-MODY in a hypothetical cohort of type 2 diabetic patients 25-40 years old with a MODY prevalence of 2%. RESEARCH DESIGN AND METHODS We used a simulation model of type 2 diabetes complications based on UK Prospective Diabetes Study data, modified to account for the natural history of disease by genetic subtype to compare a policy of genetic testing at diabetes diagnosis versus a policy of no testing. Under the screening policy, successful sulfonylurea treatment of HNF1A-MODY and HNF4A-MODY was modeled to produce a glycosylated hemoglobin reduction of -1.5% compared with usual care. GCK-MODY received no therapy. Main outcome measures were costs and quality-adjusted life years (QALYs) based on lifetime risk of complications and treatments, expressed as the incremental cost-effectiveness ratio (ICER) (USD/QALY). RESULTS The testing policy yielded an average gain of 0.012 QALYs and resulted in an ICER of 205,000 USD. Sensitivity analysis showed that if the MODY prevalence was 6%, the ICER would be ~50,000 USD. If MODY prevalence was >30%, the testing policy was cost saving. Reducing genetic testing costs to 700 USD also resulted in an ICER of ~50,000 USD. CONCLUSIONS Our simulated model suggests that a policy of testing for MODY in selected populations is cost-effective for the U.S. based on contemporary ICER thresholds. Higher prevalence of MODY in the tested population or decreased testing costs would enhance cost-effectiveness. Our results make a compelling argument for routine coverage of genetic testing in patients with high clinical suspicion of MODY.


Assuntos
Análise Custo-Benefício , Diabetes Mellitus Tipo 2/diagnóstico , Diabetes Mellitus Tipo 2/genética , Testes Genéticos/economia , Genômica/tendências , Modelos Teóricos , Pesquisa Médica Translacional/tendências , Adulto , Estudos de Coortes , Diabetes Mellitus Tipo 2/tratamento farmacológico , Feminino , Fator 1-alfa Nuclear de Hepatócito/genética , Fator 4 Nuclear de Hepatócito/genética , Humanos , Masculino , Avaliação de Resultados (Cuidados de Saúde) , Medicina de Precisão , Proteínas Serina-Treonina Quinases/genética , Anos de Vida Ajustados por Qualidade de Vida , Compostos de Sulfonilureia/uso terapêutico , Estados Unidos
19.
Pediatr Diabetes ; 15(3): 252-6, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24138066

RESUMO

Neonatal diabetes mellitus is known to have over 20 different monogenic causes. A syndrome of permanent neonatal diabetes along with primary microcephaly with simplified gyral pattern associated with severe infantile epileptic encephalopathy was recently described in two independent reports in which disease-causing homozygous mutations were identified in the immediate early response-3 interacting protein-1 (IER3IP1) gene. We report here an affected male born to a non-consanguineous couple who was noted to have insulin-requiring permanent neonatal diabetes, microcephaly, and generalized seizures. He was also found to have cortical blindness, severe developmental delay and numerous dysmorphic features. He experienced a slow improvement but not abrogation of seizure frequency and severity on numerous anti-epileptic agents. His clinical course was further complicated by recurrent respiratory tract infections and he died at 8 years of age. Whole exome sequencing was performed on DNA from the proband and parents. He was found to be a compound heterozygote with two different mutations in IER3IP1: p.Val21Gly (V21G) and a novel frameshift mutation p.Phe27fsSer*25. IER3IP1 is a highly conserved protein with marked expression in the cerebral cortex and in beta cells. This is the first reported case of compound heterozygous mutations within IER3IP1 resulting in neonatal diabetes. The triad of microcephaly, generalized seizures, and permanent neonatal diabetes should prompt screening for mutations in IER3IP1. As mutations in genes such as NEUROD1 and PTF1A could cause a similar phenotype, next-generation sequencing approaches-such as exome sequencing reported here-may be an efficient means of uncovering a diagnosis in future cases.


Assuntos
Proteínas de Transporte/genética , Diabetes Mellitus/genética , Epilepsia Generalizada/etiologia , Mutação da Fase de Leitura , Doenças do Recém-Nascido/genética , Proteínas de Membrana/genética , Microcefalia/etiologia , Mutação Puntual , Substituição de Aminoácidos , Cegueira Cortical/etiologia , Deficiências do Desenvolvimento/etiologia , Diabetes Mellitus/fisiopatologia , Diabetes Mellitus/terapia , Epilepsia Generalizada/fisiopatologia , Epilepsia Generalizada/terapia , Evolução Fatal , Heterozigoto , Humanos , Recém-Nascido , Doenças do Recém-Nascido/fisiopatologia , Masculino , Microcefalia/fisiopatologia , Microcefalia/terapia , Manifestações Neurológicas , Índice de Gravidade de Doença
20.
PLoS One ; 8(6): e65777, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23762423

RESUMO

AIMS/HYPOTHESIS: Pancreatic beta-cells retain limited ability to regenerate and proliferate after various physiologic triggers. Identifying therapies that are able to enhance beta-cell regeneration may therefore be useful for the treatment of both type 1 and type 2 diabetes. METHODS: In this study we investigated endogenous and transplanted beta-cell regeneration by serially quantifying changes in bioluminescence from beta-cells from transgenic mice expressing firefly luciferase under the control of the mouse insulin I promoter. We tested the ability of pioglitazone and alogliptin, two drugs developed for the treatment of type 2 diabetes, to enhance beta-cell regeneration, and also defined the effect of the immunosuppression with rapamycin and tacrolimus on transplanted islet beta mass. RESULTS: Pioglitazone is a stimulator of nuclear receptor peroxisome proliferator-activated receptor gamma while alogliptin is a selective dipeptidyl peptidase IV inhibitor. Pioglitazone alone, or in combination with alogliptin, enhanced endogenous beta-cell regeneration in streptozotocin-treated mice, while alogliptin alone had modest effects. In a model of syngeneic islet transplantation, immunosuppression with rapamycin and tacrolimus induced an early loss of beta-cell mass, while treatment with insulin implants to maintain normoglycemia and pioglitazone plus alogliptin was able to partially promote beta-cell mass recovery. CONCLUSIONS/INTERPRETATION: These data highlight the utility of bioluminescence for serially quantifying functional beta-cell mass in living mice. They also demonstrate the ability of pioglitazone, used either alone or in combination with alogliptin, to enhance regeneration of endogenous islet beta-cells as well as transplanted islets into recipients treated with rapamycin and tacrolimus.


Assuntos
Diabetes Mellitus Experimental/terapia , Hipoglicemiantes/farmacologia , Células Secretoras de Insulina/transplante , Piperidinas/farmacologia , Tiazolidinedionas/farmacologia , Uracila/análogos & derivados , Animais , Proliferação de Células , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/genética , Diabetes Mellitus Experimental/imunologia , Sinergismo Farmacológico , Feminino , Expressão Gênica , Genes Reporter , Imunossupressores/farmacologia , Insulina/genética , Insulina/metabolismo , Células Secretoras de Insulina/citologia , Células Secretoras de Insulina/metabolismo , Luciferases/genética , Luciferases/metabolismo , Medições Luminescentes , Masculino , Camundongos , Pioglitazona , Regiões Promotoras Genéticas , Regeneração/efeitos dos fármacos , Sirolimo/farmacologia , Estreptozocina , Tacrolimo/farmacologia , Uracila/farmacologia
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