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1.  Montreal Cognitive Assessment and Modified Mini Mental State Examination in African Americans 
Journal of Aging Research  2015;2015:872018.
Background. Sparse data limit the interpretation of Montreal Cognitive Assessment (MoCA) scores, particularly in minority populations. Additionally, there are no published data on how MoCA scores compare to the widely used Modified Mini Mental State Examination (3MSE). We provide performance data on the MoCA in a large cohort of African Americans and compare 3MSE and MoCA scores, providing a “crosswalk” for interpreting scores. Methods. Five hundred and thirty African Americans with type 2 diabetes were enrolled in African American-Diabetes Heart Study-MIND, a cross-sectional study of cognition and structural and functional brain imaging. After excluding participants with possible cognitive impairment (n = 115), mean (SD) MoCA and 3MSE scores are presented stratified by age and education. Results. Participant mean age was 58.2 years (range: 35-83); 61% were female; and 64.9% had >12 years of education. Mean (SD) 3MSE and MoCA scores were 86.9 (8.2) and 19.8 (3.8), respectively. 93.5% of the cohort had a “positive” screen on the MoCA, scoring <26 (education-adjusted), compared with 47.5% on the 3MSE (cut-point < 88). A 3MSE score of 88 corresponded to a MoCA score of 20 in this population. Conclusion. The present data suggest the need for caution when applying proposed MoCA cutoffs to African Americans.
PMCID: PMC4649096  PMID: 26618003
2.  Heritability and Genetic Association Analysis of Neuroimaging Measures in the Diabetes Heart Study 
Neurobiology of aging  2014;36(3):1602.e7-1602.e15.
Patients with type 2 diabetes are at increased risk of age-related cognitive decline and dementia. Neuroimaging measures such as white matter lesion volume, brain volume, and fractional anisotropy may reflect the pathogenesis of these cognitive declines, and genetic factors may contribute to variability in these measures. This study examined multiple neuroimaging measures in 465 participants from 238 families with extensive genotype data in the type 2 diabetes enriched Diabetes Heart Study-Mind cohort. Heritability of these phenotypes and their association with candidate single nucleotide polymorphisms (SNPs) and SNP data from genome-and exome-wide arrays was explored. All neuroimaging measures analysed were significantly heritable (ĥ2 =0.55–0.99 in unadjusted models). Seventeen candidate SNPs (from 16 genes/regions) associated with neuroimaging phenotypes in prior studies showed no significant evidence of association. A missense variant (rs150706952, A432V) in PLEKHG4B from the exome-wide array was significantly associated with white matter mean diffusivity (p=3.66×10−7) and gray matter mean diffusivity (p=2.14×10−7). This analysis suggests genetic factors contribute to variation in neuroimaging measures in a population enriched for metabolic disease and other associated comorbidities.
PMCID: PMC4346514  PMID: 25523635
Magnetic resonance imaging; type 2 diabetes; genetics; heritability
3.  Empirical Characteristics of Family-Based Linkage to a Complex Trait: the ADIPOQ Region and Adiponectin Levels 
Human genetics  2014;134(2):203-213.
We previously identified a low frequency (1.1%) coding variant (G45R; rs200573126) in the adiponectin gene (ADIPOQ) which was the basis for a multipoint microsatellite linkage signal (LOD=8.2) for plasma adiponectin levels in Hispanic families. We have empirically evaluated the ability of data from targeted common variants, exome chip genotyping, and genome-wide association study (GWAS) data to detect linkage and association to adiponectin protein levels at this locus. Simple two-point linkage and association analyses were performed in 88 Hispanic families (1150 individuals) using 10,958 SNPs on chromosome 3. Approaches were compared for their ability to map the functional variant, G45R, which was strongly linked (two-point LOD=20.98) and powerfully associated (p-value=8.1×10−50). Over 450 SNPs within a broad 61 Mb interval around rs200573126 showed nominal evidence of linkage (LOD>3) but only four other SNPs in this region were associated with p-values<1.0×10−4. When G45R was accounted for, the maximum LOD score across the interval dropped to 4.39 and the best p-value was 1.1×10−5. Linked and/or associated variants ranged in frequency (0.0018 to 0.50) and type (coding, non-coding) and had little detectable linkage disequilibrium with rs200573126 (r2<0.20). In addition, the two-point linkage approach empirically outperformed multipoint microsatellite and multipoint SNP analysis. In the absence of data for rs200573126, family-based linkage analysis using a moderately dense SNP dataset, including both common and low frequency variants, resulted in stronger evidence for an adiponectin locus than association data alone. Thus, linkage analysis can be a useful tool to facilitate identification of high impact genetic variants.
PMCID: PMC4293344  PMID: 25447270
4.  A Comparison of Type 2 Diabetes Risk Allele Load between African Americans and European Americans 
Human genetics  2014;133(12):1487-1495.
The prevalence of type 2 diabetes (T2D) is greater in populations of African descent compared to European-descent populations. Genetic risk factors may underlie the disparity in disease prevalence. Genome-wide association studies (GWAS) have identified >60 common genetic variants that contribute to T2D risk in populations of European, Asian, African, and Hispanic descent. These studies have not comprehensively examined population differences in cumulative risk allele load. To investigate the relationship between risk allele load and T2D risk, 46 T2D single nucleotide polymorphisms (SNPs) in 43 loci from GWAS in European, Asian, and African derived populations were genotyped in 1,990 African Americans (n=963 T2D cases, n=1,027 controls) and 1,644 European Americans (n=719 T2D cases, n=925 controls) ascertained and recruited using a common protocol in the southeast United States. A genetic risk score (GRS) was constructed from the cumulative risk alleles for each individual. In African American subjects, risk allele frequencies ranged from 0.024 to 0.964. Risk alleles from 26 SNPs demonstrated directional consistency with previous studies, and 3 SNPs from ADAMTS9, TCF7L2, and ZFAND6 showed nominal evidence of association (p<0.05). African American individuals carried 38–67 (53.7 ± 4.0, mean ± SD) risk alleles. In European American subjects, risk allele frequencies ranged from 0.084 to 0.996. Risk alleles from 36 SNPs demonstrated directional consistency, and 10 SNPs from BCL11A, PSMD6, ADAMTS9, ZFAND3, ANK1, CDKN2A/B, TCF7L2, PRC1, FTO, and BCAR1 showed evidence of association (p<0.05). European American individuals carried 38–65 (50.9 ± 4.4) risk alleles. African Americans have a significantly greater burden of 2.9 risk alleles (p=3.97×10−89) compared to European Americans. However, GRS modeling showed that cumulative risk allele load was associated with risk of T2D in European Americans, but only marginally in African Americans. This result suggests that there are ethnic-specific differences in genetic architecture underlying T2D, and that these differences complicate our understanding of how risk allele load impacts disease susceptibility.
PMCID: PMC4225163  PMID: 25273842
diabetes type 2; African American; genetic association; genetic relationship analysis; age at onset
5.  Contributors to Mortality in High-Risk Diabetic Patients in the Diabetes Heart Study 
Diabetes Care  2014;37(10):2798-2803.
Not all individuals with type 2 diabetes and high coronary artery calcified plaque (CAC) experience the same risk for adverse outcomes. This study examined a subset of high-risk individuals based on CAC >1,000 mg (using a total mass score) and evaluated whether differences in a range of modifiable cardiovascular disease (CVD) risk factors provided further insights into risk for mortality.
We assessed contributors to all-cause mortality among 371 European American individuals with type 2 diabetes and CAC >1,000 from the Diabetes Heart Study (DHS) after 8.2 ± 3.0 years (mean ± SD) of follow-up. Differences in known CVD risk factors, including modifiable CVD risk factors, were compared between living (n = 218) and deceased (n = 153) participants. Cox proportional hazards regression models were used to quantify risk for all-cause mortality.
Deceased participants had a longer duration of type 2 diabetes (P = 0.02) and reduced use of cholesterol-lowering medications (P = 0.004). Adjusted analyses revealed that vascular calcified plaque scores were associated with increased risk for mortality (hazard ratio 1.31–1.63; 3.89 × 10−5 < P < 0.03). Higher HbA1c, lipids, and C-reactive protein and reduced kidney function also were associated with a 1.1- to 1.5-fold increased risk for mortality (3.45 × 10−6 < P < 0.03) after adjusting for confounding factors.
Even in this high-risk group, vascular calcification and known CVD risk factors provide useful information for ongoing assessment. The use of cholesterol-lowering medication seemed to be protective for mortality.
PMCID: PMC4392938  PMID: 24989706
6.  Epigenetic profiles of pre-diabetes transitioning to type 2 diabetes and nephropathy 
World Journal of Diabetes  2015;6(9):1113-1121.
AIM: To examine DNA methylation profiles in a longitudinal comparison of pre-diabetes mellitus (Pre-DM) subjects who transitioned to type 2 diabetes mellitus (T2DM).
METHODS: We performed DNA methylation study in bisulphite converted DNA from Pre-DM (n = 11) at baseline and at their transition to T2DM using Illumina Infinium HumanMethylation27 BeadChip, that enables the query of 27578 individual cytosines at CpG loci throughout the genome, which are focused on the promoter regions of 14495 genes.
RESULTS: There were 694 CpG sites hypomethylated and 174 CpG sites hypermethylated in progression from Pre-DM to T2DM, representing putative genes involved in glucose and fructose metabolism, inflammation, oxidative and mitochondrial stress, and fatty acid metabolism. These results suggest that this high throughput platform is able to identify hundreds of prospective CpG sites associated with diverse genes that may reflect differences in Pre-DM compared with T2DM. In addition, there were CpG hypomethylation changes associated with a number of genes that may be associated with development of complications of diabetes, such as nephropathy. These hypomethylation changes were observed in all of the subjects.
CONCLUSION: These data suggest that some epigenomic changes that may be involved in the progression of diabetes and/or the development of complications may be apparent at the Pre-DM state or during the transition to diabetes. Hypomethylation of a number of genes related to kidney function may be an early marker for developing diabetic nephropathy.
PMCID: PMC4530325  PMID: 26265998
Epigenetic changes; Pre-diabetes; Diabetes; Nephropathy
7.  Deceased donor multidrug resistance protein 1 and caveolin 1 gene variants may influence allograft survival in kidney transplantation 
Kidney international  2015;88(3):584-592.
Variants in donor multidrug resistance protein 1 (ABCB1) and caveolin 1 (CAV1) genes are associated with renal allograft failure after transplantation in Europeans. Here we assessed transplantation outcomes of kidneys from 368 African American (AA) and 314 European American (EA) deceased donors based on 38 single nucleotide polymorphisms (SNPs) spanning ABCB1 and 16 SNPs spanning CAV1, including previously associated index and haplotype-tagging SNPs. Tests for association with time to allograft failure were performed for the 1,233 resultant kidney transplantations, adjusting for recipient age, sex, ethnicity, cold ischemia time, PRA, HLA match, expanded-criteria donation, and APOL1- nephropathy variants in AA donors. Interaction analyses between APOL1 with ABCB1 and CAV1 were performed. In a meta-analysis of all transplantations, ABCB1 index SNP rs1045642 was associated with time to allograft failure and other ABCB1 SNPs were nominally associated, but not CAV1 SNPs. ABCB1 SNP rs1045642 showed consistent effects with the 558 transplantations from EA donors, but not with the 675 transplantations from AA donors. ABCB1 SNP rs956825 and CAV1 SNP rs6466583 interacted with APOL1 in transplants from AA donors. Thus, the T allele at ABCB1 rs1045642 is associated with shorter renal allograft survival for kidneys from American donors. Interactions between ABCB1 and CAV1 with APOL1 may influence allograft failure for transplanted kidneys from AA donors.
PMCID: PMC4556550  PMID: 25853335
African American; allograft failure; ABCB1; APOL1; CAV1; kidney transplantation
8.  Analysis of Coding Variants Identified from Exome Sequencing Resources for Association with Diabetic and Non-diabetic Nephropathy in African Americans 
Human genetics  2014;133(6):769-779.
Prior studies have identified common genetic variants influencing diabetic and non-diabetic nephropathy, diseases which disproportionately affect African Americans. Recently, exome sequencing techniques have facilitated identification of coding variants on a genome-wide basis in large samples. Exonic variants in known or suspected end-stage kidney disease (ESKD) or nephropathy genes can be tested for their ability to identify association either singly or in combination with known associated common variants. Coding variants in genes with prior evidence for association with ESKD or nephropathy were identified in the NHLBI-ESP GO database and genotyped in 5045 African Americans (3324 cases with type 2 diabetes associated nephropathy [T2D-ESKD] or non-T2D ESKD, and 1721 controls) and 1465 European Americans (568 T2D-ESKD cases and 897 controls). Logistic regression analyses were performed to assess association, with admixture and APOL1 risk status incorporated as covariates. Ten of 31 SNPs were associated in African Americans; four replicated in European Americans. In African Americans, SNPs in OR2L8, OR2AK2, C6orf167 (MMS22L), LIMK2, APOL3, APOL2, and APOL1 were nominally associated (P=1.8×10−4-0.044). Haplotype analysis of common and coding variants increased evidence of association at the OR2L13 and APOL1 loci (P=6.2×10−5 and 4.6×10−5, respectively). SNPs replicating in European Americans were in OR2AK2, LIMK2, and APOL2 (P=0.0010-0.037). Meta-analyses highlighted four SNPs associated in T2DESKD and all-cause ESKD. Results from this study suggest a role for coding variants in the development of diabetic, non-diabetic, and/or all-cause ESKD in African Americans and/or European Americans.
PMCID: PMC4024071  PMID: 24385048
African Americans; Association; European Americans; Exonic Variants; Type 2 Diabetes; Nephropathy
9.  Heart Rate–Corrected QT Interval Is an Independent Predictor of All-Cause and Cardiovascular Mortality in Individuals With Type 2 Diabetes: The Diabetes Heart Study 
Diabetes Care  2014;37(5):1454-1461.
Heart rate–corrected QT (QTc) interval is associated with mortality in the general population, but this association is less clear in individuals with type 2 diabetes. We assessed the association of QTc interval with all-cause and cardiovascular disease (CVD) mortality in the Diabetes Heart Study.
We studied 1,020 participants with type 2 diabetes (83% European Americans; 55% women; mean age 61.4 years) who were free of atrial fibrillation, major ventricular conduction defects, and antiarrhythmic therapy at baseline. QT duration was automatically calculated from a standard 12-lead electrocardiogram (ECG). Following American Heart Association/American College of Cardiology Foundation recommendations, a linear scale was used to correct the QT for heart rate. Using Cox regression, risk was estimated per 1-SD increase in QTc interval as well as prolonged QTc interval (>450 ms) vs. normal QTc interval for mortality.
At baseline, the mean (SD) QTc duration was 414.9 ms (18.1), and 3.0% of participants had prolonged QTc. After a median follow-up time of 8.5 years (maximum follow-up time 13.9 years), 204 participants were deceased. In adjusted multivariate models, a 1-SD increase in QTc interval was associated with an 18% higher risk for all-cause mortality (hazard ratio 1.18 [95% CI 1.03–1.36]) and 29% increased risk for CVD mortality (1.29 [1.05–1.59]). Similar results were obtained when QTc interval was used as a categorical variable (prolonged vs. normal) (all-cause mortality 1.73 [0.95–3.15]; CVD mortality 2.86 [1.35–6.08]).
Heart rate QTc interval is an independent predictor of all-cause and CVD mortality in this population with type 2 diabetes, suggesting that additional prognostic information may be available from this simple ECG measure.
PMCID: PMC4182905  PMID: 24574343
10.  Genetic Risk Score Associations With Cardiovascular Disease and Mortality in the Diabetes Heart Study 
Diabetes Care  2014;37(4):1157-1164.
Given the high rates of cardiovascular disease (CVD) and associated mortality in individuals with type 2 diabetes, identifying and understanding predictors of CVD events and mortality could help inform clinical management in this high-risk group. Recent large-scale genetic studies may provide additional tools in this regard.
Genetic risk scores (GRSs) were constructed in 1,175 self-identified European American (EA) individuals comprising the family-based Diabetes Heart Study based on 1) 13 single nucleotide polymorphisms (SNPs) and 2) 30 SNPs with previously documented associations with CVD in genome-wide association studies. Associations between each GRS and a self-reported history of CVD, coronary artery calcified plaque (CAC) determined by noncontrast computed tomography scan, all-cause mortality, and CVD mortality were examined using marginal models with generalized estimating equations and Cox proportional hazards models.
The weighted 13-SNP GRS was associated with prior CVD (odds ratio [OR] 1.51 [95% CI 1.22–1.86]; P = 0.0002), CAC (β-coefficient [β] 0.22 [0.02–0.43]; P = 0.04) and CVD mortality (hazard ratio [HR] 1.35 [1.10–1.81]; P = 0.04) when adjusting for the other known CVD risk factors: age, sex, type 2 diabetes affection status, BMI, current smoking status, hypertension, and dyslipidemia. The weighted 30-SNP GRS was also associated with prior CVD (OR 1.33 [1.08–1.65]; P = 0.008), CAC (β 0.29 [0.08–0.50]; P = 0.006), all-cause mortality (HR 1.28 [1.05–1.56]; P = 0.01), and CVD mortality (HR 1.46 [1.08–1.96]; P = 0.01).
These findings support the utility of two simple GRSs in examining genetic associations for adverse outcomes in EAs with type 2 diabetes.
PMCID: PMC4178326  PMID: 24574349
11.  Genetic variants in Selenoprotein P plasma 1 gene (SEPP1) are associated with fasting insulin and first phase insulin response in Hispanics 
Gene  2013;534(1):10.1016/j.gene.2013.10.035.
Insulin resistance is not fully explained on a molecular level, though several genes and proteins have been tied to this defect. Knockdowns of the SEPP1 gene, which encodes the Selenoprotein P (SeP) protein, have been shown to increase insulin sensitivity in mice. SeP is a liver-derived plasma protein and a major supplier of selenium, which is a proposed insulin mimetic and antidiabetic agent.
SEPP1 single nucleotide polymorphisms (SNPs) were selected for analysis with glucometabolic measures.
Participants and Measures
1424 Hispanics from families in the Insulin Resistance Atherosclerosis Family Study (IRASFS). Additionally, the multi-ethnic Insulin Resistance Atherosclerosis Study was used. A frequently sampled intravenous glucose tolerance test was used to obtain precise measures of acute insulin response (AIR) and the insulin sensitivity index (SI).
21 SEPP1 SNPs (tagging SNPs (n=12) from HapMap, 4 coding variants and 6 SNPs in the promoter region) were genotyped and analyzed for association.
Two highly correlated (r2=1) SNPs showed association with AIR (rs28919926; Cys368Arg; p=0.0028 and rs146125471; Ile293Met; p=0.0026) while rs16872779 (intronic) was associated with fasting insulin levels (p=0.0097). In the smaller IRAS Hispanic cohort, few of the associations seen in the IRASFS were replicated, but meta-analysis of IRASFS and all 3 IRAS cohorts (N= 2446) supported association of rs28919926 and rs146125471 with AIR (p=0.013 and 0.0047, respectively) as well as rs7579 with SI (p=0.047).
Overall, these results in a human sample are consistent with the literature suggesting a role for SEPP1 in insulin resistance.
PMCID: PMC3856675  PMID: 24161883
Acute Insulin Response (AIR); Selenium; Selenoproteins; Insulin Resistance; Fibrinogen; Hispanic Americans
12.  Genome-Wide Family-Based Linkage Analysis of Exome Chip Variants and Cardiometabolic Risk 
Genetic epidemiology  2014;38(4):345-352.
Linkage analysis of complex traits has had limited success in identifying trait-influencing loci. Recently, coding variants have been implicated as the basis for some biomedical associations. We tested whether coding variants are the basis for linkage peaks of complex traits in 42 African-American (n = 596) and 90 Hispanic (n = 1,414) families in the Insulin Resistance Atherosclerosis Family Study (IRASFS) using Illumina HumanExome Beadchips. A total of 92,157 variants in African Americans (34%) and 81,559 (31%) in Hispanics were polymorphic and tested using two-point linkage and association analyses with 37 cardiometabolic phenotypes. In African Americans 77 LOD scores greater than 3 were observed. The highest LOD score was 4.91 with the APOE SNP rs7412 (MAF = 0.13) with plasma apolipoprotein B (ApoB). This SNP was associated with ApoB (P-value = 4 × 10−19) and accounted for 16.2% of the variance in African Americans. In Hispanic families, 104 LOD scores were greater than 3. The strongest evidence of linkage (LOD = 4.29) was with rs5882 (MAF = 0.46) in CETP with HDL. CETP variants were strongly associated with HDL (0.00049 < P-value <4.6 × 10−12), accounting for up to 4.5% of the variance. These loci have previously been shown to have effects on the biomedical traits evaluated here. Thus, evidence of strong linkage in this genome wide survey of primarily coding variants was uncommon. Loci with strong evidence of linkage was characterized by large contributions to the variance, and, in these cases, are common variants. Less compelling evidence of linkage and association was observed with additional loci that may require larger family sets to confirm.
PMCID: PMC4281959  PMID: 24719370
Hispanic; African American; genetic variance
13.  The ras responsive transcription factor RREB1 is a novel candidate gene for type 2 diabetes associated end-stage kidney disease 
Human Molecular Genetics  2014;23(24):6441-6447.
Familial clustering and presumed genetic risk for type 2 diabetic (T2D) and non-diabetic end-stage kidney disease (ESKD) appear strong in African Americans. Examination of exome sequencing data in African American T2D-ESKD cases and non-diabetic non-nephropathy controls identified two low-frequency variants in the RREB1 gene, a repressor of the angiotensinogen (AGT) gene previously associated with kidney function, as being associated with T2D-ESKD: rs9379084 (P = 0.00087, OR = 0.26; D1171N) and rs41302867 (P = 0.00078, OR = 0.21; splice site variant). Rs41302867 replicated association in an independent sample of African Americans with T2D-ESKD [rs41302867 P = 0.033 (OR = 0.50)], and a trend towards rs9379084 association was observed (P = 0.070). In European Americans with T2D-ESKD compared with European American population based controls, both RREB1 variants replicated association [rs9379084 P = 1.67 × 10−4 (OR = 0.54) and rs41302867 P = 0.013 (OR = 0.69)]. Rs9379084 was not associated with non-T2D-ESKD or T2D in African Americans (P = 0.55 and P = 0.37, respectively), but was associated with T2D in European Americans (P = 0.014, OR = 0.65). In African Americans, rs41302867 was associated with non-T2D-ESKD [P = 0.036 (OR = 0.54)] and hypertension attributed ESKD [H-ESKD, P = 0.029 (OR = 0.50)]. A meta-analysis combining African American and European American T2D-ESKD data revealed P = 3.52 × 10−7 and 3.70 × 10−5 for rs9379084 and rs41302867 association, respectfully. A locus-wide analysis evaluating putatively functional SNPs revealed several nominal associations with T2D-ESKD, non-T2D-ESKD and T2D in African and European Americans. RREB1 is a large, complex gene which codes a multidomain zinc finger binding protein and transcription factor. We posit that variants in RREB1 modulate seemingly disparate phenotypes (i.e. T2D, T2D-ESKD and non-T2D-ESKD) through altered activity resulting from splice site and missense variants.
PMCID: PMC4240197  PMID: 25027322
14.  Prevalence and Determinants of Electrocardiographic Abnormalities in African Americans with Type 2 Diabetes 
Electrocardiographic (ECG) abnormalities are independently associated with poor outcomes in the general population. Their prevalence and determinants were assessed in the understudied African American population with type 2 diabetes.
Standard 12-lead ECGs were digitally recorded in 635 unrelated African American-Diabetes Heart Study (AA-DHS) participants, automatically processed at a central lab, read, and coded using standard Minnesota ECG Classification. Age- and sex-specific prevalence rates of ECG abnormalities were calculated and logistic regression models were fitted to examine cross-sectional associations between participant characteristics and ECG abnormalities.
Participants were 56% women with a mean age of 56 years; 60% had at least one minor or major ECG abnormality [23% ≥1 major (or major plus minor), and 37% ≥1 minor (with no major)]. Men had a higher prevalence of ≥1 minor or major ECG abnormality (66.1% men vs. 55.6% women, p=0.0089). In univariate analyses, age, past history of cardiovascular disease, diabetes duration, systolic blood pressure, sex and statin use were associated with the presence of any (major or minor) ECG abnormalities. In a multivariate model including variables, female sex (OR [95% CI] 0.79 [0.67,0.93]), statin use (0.79 [0.67,0.93]) and diabetes duration (1.03 [1.0,1.05]) remained statistically significant.
Nearly three out of five African Americans with diabetes had at least one ECG abnormality. Female sex and statin use were significantly associated with lower odds of any ECG abnormality and diabetes duration was significantly associated with higher odds of any ECG abnormality in the multivariable model.
PMCID: PMC4254487  PMID: 25455646
Electrocardiogram; Diabetes; African Americans; Heart; Hypertension; Cardiovascular Disease
15.  A Comprehensive Analysis of Common and Rare Variants to Identify Adiposity Loci in Hispanic Americans: The IRAS Family Study (IRASFS) 
PLoS ONE  2015;10(11):e0134649.
Obesity is growing epidemic affecting 35% of adults in the United States. Previous genome-wide association studies (GWAS) have identified numerous loci associated with obesity. However, the majority of studies have been completed in Caucasians focusing on total body measures of adiposity. Here we report the results from genome-wide and exome chip association studies focusing on total body measures of adiposity including body mass index (BMI), percent body fat (PBF) and measures of fat deposition including waist circumference (WAIST), waist-hip ratio (WHR), subcutaneous adipose tissue (SAT), and visceral adipose tissue (VAT) in Hispanic Americans (nmax = 1263) from the Insulin Resistance Atherosclerosis Family Study (IRASFS). Five SNPs from two novel loci attained genome-wide significance (P<5.00x10-8) in IRASFS. A missense SNP in the isocitrate dehydrogenase 1 gene (IDH1) was associated with WAIST (rs34218846, MAF = 6.8%, PDOM = 1.62x10-8). This protein is postulated to play an important role in fat and cholesterol biosynthesis as demonstrated in cell and knock-out animal models. Four correlated intronic SNPs in the Zinc finger, GRF-type containing 1 gene (ZGRF1; SNP rs1471880, MAF = 48.1%, PDOM = 1.00x10-8) were strongly associated with WHR. The exact biological function of ZGRF1 and the connection with adiposity remains unclear. SNPs with p-values less than 5.00x10-6 from IRASFS were selected for replication. Meta-analysis was computed across seven independent Hispanic-American cohorts (nmax = 4156) and the strongest signal was rs1471880 (PDOM = 8.38x10-6) in ZGRF1 with WAIST. In conclusion, a genome-wide and exome chip association study was conducted that identified two novel loci (IDH1 and ZGRF1) associated with adiposity. While replication efforts were inconclusive, when taken together with the known biology, IDH1 and ZGRF1 warrant further evaluation.
PMCID: PMC4658008  PMID: 26599207
16.  Polymorphisms in the Selenoprotein S gene and subclinical cardiovascular disease in the Diabetes Heart Study 
Acta diabetologica  2012;50(3):391-399.
Selenoprotein S (SelS), has previously been associated with a range of inflammatory markers, particularly in the context of cardiovascular disease (CVD). The aim of this study was to examine the role of SELS genetic variants in risk for subclinical CVD and mortality in individuals with type 2 diabetes mellitus (T2DM). The association between 10 polymorphisms tagging SELS and coronary (CAC), carotid (CarCP) and abdominal-aortic calcified plaque (AACP), carotid intima media thickness (IMT) and other known CVD risk factors was examined in 1220 European Americans from the family-based Diabetes Heart Study. The strongest evidence of association for SELS SNPs was observed for CarCP; rs28665122 (5′ region; β=0.329, p=0.044), rs4965814 (intron 5; β=0.329, p=0.036), rs28628459 (3′ region; β=0.331, p=0.039) and rs7178239 (downstream; β=0.375, p=0.016) were all associated. In addition, rs12917258 (intron 5) was associated with CAC (β =−0.230, p=0.032) and rs4965814, rs28628459 and rs9806366 were all associated with self reported history of prior CVD (p=0.020–0.043). These results suggest a potential role for the SELS region in the development subclinical CVD in this sample enriched for T2DM. Further understanding the mechanisms underpinning these relationships may prove important in predicting and managing CVD complications in T2DM.
PMCID: PMC3597768  PMID: 23161441
genetics; atherosclerosis; calcified plaque; diabetes mellitus
17.  Genetic Analysis of Adiponectin Variation and its Association with Type 2 Diabetes in African Americans 
Obesity (Silver Spring, Md.)  2013;21(12):10.1002/oby.20419.
Adiponectin is an adipocytokine that has been implicated in a variety of metabolic disorders, including T2D and cardiovascular disease. Studies evaluating genetic variants in ADIPOQ have been contradictory when testing association with T2D in different ethnic groups.
Design and Methods
In this study, 18 SNPs in ADIPOQ were tested for association with plasma adiponectin levels and diabetes status. SNPs were examined in two independent African-American cohorts (nmax=1116) from the Insulin Resistance Atherosclerosis Family Study (IRASFS) and the African American-Diabetes Heart Study (AA-DHS).
Five polymorphisms were nominally associated with plasma adiponectin levels in the meta-analysis (p=0.035–1.02x10−6) including a low frequency arginine to cysteine mutation (R55C) which reduced plasma adiponectin levels to <15% of the mean. Variants were then tested for association with T2D in a meta-analysis of these and the Wake Forest T2D Case-Control study (n=3233 T2D, 2645 non-T2D). Association with T2D was not observed (p≥0.08), suggesting limited influence of ADIPOQ variants on T2D risk.
Despite identification of variants associated with adiponectin levels, a detailed genetic analysis of ADIPOQ revealed no association with T2D risk. This puts into question the role of adiponectin in T2D pathogenesis: whether low adiponectin levels are truly causal for or rather a consequence.
PMCID: PMC3690163  PMID: 23512866
18.  Coronary Calcium Score Predicts Cardiovascular Mortality in Diabetes 
Diabetes Care  2013;36(4):972-977.
In type 2 diabetes mellitus (T2DM), it remains unclear whether coronary artery calcium (CAC) provides additional information about cardiovascular disease (CVD) mortality beyond the Framingham Risk Score (FRS) factors.
A total of 1,123 T2DM participants, ages 34–86 years, in the Diabetes Heart Study followed up for an average of 7.4 years were separated using baseline computed tomography scans of CAC (0–9, 10–99, 100–299, 300–999, and ≥1,000). Logistic regression was performed to examine the association between CAC and CVD mortality adjusting for FRS. Areas under the curve (AUC) with and without CAC were compared. Net reclassification improvement (NRI) compared FRS (model 1) versus FRS+CAC (model 2) using 7.4-year CVD mortality risk categories 0% to <7%, 7% to <20%, and ≥20%.
Overall, 8% of participants died of cardiovascular causes during follow-up. In multivariate analysis, the odds ratios (95% CI) for CVD mortality using CAC 0–9 as the reference group were, CAC 10–99: 2.93 (0.74–19.55); CAC 100–299: 3.17 (0.70–22.22); CAC 300–999: 4.41(1.15–29.00); and CAC ≥1,000: 11.23 (3.24–71.00). AUC (95% CI) without CAC was 0.70 (0.67–0.73), AUC with CAC was 0.75 (0.72–0.78), and NRI was 0.13 (0.07–0.19).
In T2DM, CAC predicts CVD mortality and meaningfully reclassifies participants, suggesting clinical utility as a risk stratification tool in a population already at increased CVD risk.
PMCID: PMC3609509  PMID: 23230101
19.  Low-frequency and rare exome chip variants associate with fasting glucose and type 2 diabetes susceptibility 
Wessel, Jennifer | Chu, Audrey Y. | Willems, Sara M. | Wang, Shuai | Yaghootkar, Hanieh | Brody, Jennifer A. | Dauriz, Marco | Hivert, Marie-France | Raghavan, Sridharan | Lipovich, Leonard | Hidalgo, Bertha | Fox, Keolu | Huffman, Jennifer E. | An, Ping | Lu, Yingchang | Rasmussen-Torvik, Laura J. | Grarup, Niels | Ehm, Margaret G. | Li, Li | Baldridge, Abigail S. | Stančáková, Alena | Abrol, Ravinder | Besse, Céline | Boland, Anne | Bork-Jensen, Jette | Fornage, Myriam | Freitag, Daniel F. | Garcia, Melissa E. | Guo, Xiuqing | Hara, Kazuo | Isaacs, Aaron | Jakobsdottir, Johanna | Lange, Leslie A. | Layton, Jill C. | Li, Man | Zhao, Jing Hua | Meidtner, Karina | Morrison, Alanna C. | Nalls, Mike A. | Peters, Marjolein J. | Sabater-Lleal, Maria | Schurmann, Claudia | Silveira, Angela | Smith, Albert V. | Southam, Lorraine | Stoiber, Marcus H. | Strawbridge, Rona J. | Taylor, Kent D. | Varga, Tibor V. | Allin, Kristine H. | Amin, Najaf | Aponte, Jennifer L. | Aung, Tin | Barbieri, Caterina | Bihlmeyer, Nathan A. | Boehnke, Michael | Bombieri, Cristina | Bowden, Donald W. | Burns, Sean M. | Chen, Yuning | Chen, Yii-Der I. | Cheng, Ching-Yu | Correa, Adolfo | Czajkowski, Jacek | Dehghan, Abbas | Ehret, Georg B. | Eiriksdottir, Gudny | Escher, Stefan A. | Farmaki, Aliki-Eleni | Frånberg, Mattias | Gambaro, Giovanni | Giulianini, Franco | III, William A. Goddard | Goel, Anuj | Gottesman, Omri | Grove, Megan L. | Gustafsson, Stefan | Hai, Yang | Hallmans, Göran | Heo, Jiyoung | Hoffmann, Per | Ikram, Mohammad K. | Jensen, Richard A. | Jørgensen, Marit E. | Jørgensen, Torben | Karaleftheri, Maria | Khor, Chiea C. | Kirkpatrick, Andrea | Kraja, Aldi T. | Kuusisto, Johanna | Lange, Ethan M. | Lee, I.T. | Lee, Wen-Jane | Leong, Aaron | Liao, Jiemin | Liu, Chunyu | Liu, Yongmei | Lindgren, Cecilia M. | Linneberg, Allan | Malerba, Giovanni | Mamakou, Vasiliki | Marouli, Eirini | Maruthur, Nisa M. | Matchan, Angela | McKean, Roberta | McLeod, Olga | Metcalf, Ginger A. | Mohlke, Karen L. | Muzny, Donna M. | Ntalla, Ioanna | Palmer, Nicholette D. | Pasko, Dorota | Peter, Andreas | Rayner, Nigel W. | Renström, Frida | Rice, Ken | Sala, Cinzia F. | Sennblad, Bengt | Serafetinidis, Ioannis | Smith, Jennifer A. | Soranzo, Nicole | Speliotes, Elizabeth K. | Stahl, Eli A. | Stirrups, Kathleen | Tentolouris, Nikos | Thanopoulou, Anastasia | Torres, Mina | Traglia, Michela | Tsafantakis, Emmanouil | Javad, Sundas | Yanek, Lisa R. | Zengini, Eleni | Becker, Diane M. | Bis, Joshua C. | Brown, James B. | Cupples, L. Adrienne | Hansen, Torben | Ingelsson, Erik | Karter, Andrew J. | Lorenzo, Carlos | Mathias, Rasika A. | Norris, Jill M. | Peloso, Gina M. | Sheu, Wayne H.-H. | Toniolo, Daniela | Vaidya, Dhananjay | Varma, Rohit | Wagenknecht, Lynne E. | Boeing, Heiner | Bottinger, Erwin P. | Dedoussis, George | Deloukas, Panos | Ferrannini, Ele | Franco, Oscar H. | Franks, Paul W. | Gibbs, Richard A. | Gudnason, Vilmundur | Hamsten, Anders | Harris, Tamara B. | Hattersley, Andrew T. | Hayward, Caroline | Hofman, Albert | Jansson, Jan-Håkan | Langenberg, Claudia | Launer, Lenore J. | Levy, Daniel | Oostra, Ben A. | O'Donnell, Christopher J. | O'Rahilly, Stephen | Padmanabhan, Sandosh | Pankow, James S. | Polasek, Ozren | Province, Michael A. | Rich, Stephen S. | Ridker, Paul M | Rudan, Igor | Schulze, Matthias B. | Smith, Blair H. | Uitterlinden, André G. | Walker, Mark | Watkins, Hugh | Wong, Tien Y. | Zeggini, Eleftheria | Scotland, Generation | Laakso, Markku | Borecki, Ingrid B. | Chasman, Daniel I. | Pedersen, Oluf | Psaty, Bruce M. | Tai, E. Shyong | van Duijn, Cornelia M. | Wareham, Nicholas J. | Waterworth, Dawn M. | Boerwinkle, Eric | Kao, WH Linda | Florez, Jose C. | Loos, Ruth J.F. | Wilson, James G. | Frayling, Timothy M. | Siscovick, David S. | Dupuis, Josée | Rotter, Jerome I. | Meigs, James B. | Scott, Robert A. | Goodarzi, Mark O.
Nature communications  2015;6:5897.
Fasting glucose and insulin are intermediate traits for type 2 diabetes. Here we explore the role of coding variation on these traits by analysis of variants on the HumanExome BeadChip in 60,564 non-diabetic individuals and in 16,491 T2D cases and 81,877 controls. We identify a novel association of a low-frequency nonsynonymous SNV in GLP1R (A316T; rs10305492; MAF=1.4%) with lower FG (β=-0.09±0.01 mmol L−1, p=3.4×10−12), T2D risk (OR[95%CI]=0.86[0.76-0.96], p=0.010), early insulin secretion (β=-0.07±0.035 pmolinsulin mmolglucose−1, p=0.048), but higher 2-h glucose (β=0.16±0.05 mmol L−1, p=4.3×10−4). We identify a gene-based association with FG at G6PC2 (pSKAT=6.8×10−6) driven by four rare protein-coding SNVs (H177Y, Y207S, R283X and S324P). We identify rs651007 (MAF=20%) in the first intron of ABO at the putative promoter of an antisense lncRNA, associating with higher FG (β=0.02±0.004 mmol L−1, p=1.3×10−8). Our approach identifies novel coding variant associations and extends the allelic spectrum of variation underlying diabetes-related quantitative traits and T2D susceptibility.
PMCID: PMC4311266  PMID: 25631608
Genetic epidemiology  2012;37(1):13-24.
Common genetic variation frequently accounts for only a modest amount of inter-individual variation in quantitative traits and complex disease susceptibility. Circulating adiponectin, an adipocytokine implicated in metabolic disease, is a model for assessing the contribution of genetic and clinical factors to quantitative trait variation. The adiponectin locus, ADIPOQ, is the primary source of genetically-mediated variation in plasma adiponectin levels. This study sought to define the genetic architecture of ADIPOQ in the comprehensively phenotyped Hispanic (n=1151) and African American (n=574) participants from the Insulin Resistance Atherosclerosis Family Study (IRASFS). Through resequencing and bioinformatic analysis, rare/low frequency (<5% MAF) and common variants (>5% MAF) in ADIPOQ were identified. Genetic variants and clinical variables were assessed for association with adiponectin levels and contribution to adiponectin variance in the Hispanic and African American cohorts. Clinical traits accounted for the greatest proportion of variance (POV) at 31% (p=1.16×10−47) and 47% (p=5.82×10−20), respectively. Rare/low frequency variants contributed more than common variants to variance in Hispanics: POV=18% (p= 6.40×10−15) and POV=5% (p=0.19), respectively. In African Americans, rare/low frequency and common variants both contributed approximately equally to variance: POV=6% (p=5.44×10−12) and POV=9% (P=1.44×10−10), respectively. Importantly, single low frequency alleles in each ethnic group were as important as, or more important than, common variants in explaining variation in adiponectin. Cumulatively, these clinical and ethnicity-specific genetic contributors explained half or more of the variance in Hispanic and African Americans and provide new insight into the sources of variation for this important adipocytokine.
PMCID: PMC3736586  PMID: 23032297
adiponectin; proportion of variation; rare variants; common variants; clinical traits
21.  Complement factor H gene associations with end-stage kidney disease in African Americans 
Nephrology Dialysis Transplantation  2014;29(7):1409-1414.
Mutations in the complement factor H gene (CFH) region associate with renal-limited mesangial proliferative forms of glomerulonephritis including IgA nephropathy (IgAN), dense deposit disease (DDD) and C3 glomerulonephritis (C3GN). Lack of kidney biopsies could lead to under diagnosis of CFH-associated end-stage kidney disease (ESKD) in African Americans (AAs), with incorrect attribution to other causes. A prior genome-wide association study in AAs with non-diabetic ESKD implicated an intronic CFH single nucleotide polymorphism (SNP).
Thirteen CFH SNPs (8 exonic, 2 synonymous, 2 3′UTR, and the previously associated intronic variant rs379489) were tested for association with common forms of non-diabetic and type 2 diabetes-associated (T2D) ESKD in 3770 AAs (1705 with non-diabetic ESKD, 1305 with T2D-ESKD, 760 controls). Most cases lacked kidney biopsies; those with known IgAN, DDD or C3GN were excluded.
Adjusting for age, gender, ancestry and apolipoprotein L1 gene risk variants, single SNP analyses detected 6 CFH SNPs (5 exonic and the intronic variant) as significantly associated with non-diabetic ESKD (P = 0.002–0.01), three of these SNPs were also associated with T2D-ESKD. Weighted CFH locus-wide Sequence Kernel Association Testing (SKAT) in non-diabetic ESKD (P = 0.00053) and T2D-ESKD (P = 0.047) confirmed significant evidence of association.
CFH was associated with commonly reported etiologies of ESKD in the AA population. These results suggest that a subset of cases with ESKD clinically ascribed to the effects of hypertension or glomerulosclerosis actually have CFH-related forms of mesangial proliferative glomerulonephritis. Genetic testing may prove useful to identify the causes of renal-limited kidney disease in patients with ESKD who lack renal biopsies.
PMCID: PMC4081633  PMID: 24586071
African Americans; CFH; end-stage kidney disease; genetics; kidney disease
22.  APOL1 associations with nephropathy, atherosclerosis, and all-cause mortality in African Americans with type 2 diabetes 
Kidney international  2014;87(1):176-181.
Albuminuria and reduced eGFR associate with two apolipoprotein L1 gene (APOL1) variants in non-diabetic African Americans. Whether APOL1 associates with subclinical atherosclerosis and survival remains unclear. To determine this, 717 African American-Diabetes Heart Study participants underwent computed tomography to determine coronary artery, carotid artery, and aorta calcified atherosclerotic plaque mass scores in addition to the urine albumin:creatinine ratio (UACR), eGFR, and C-reactive protein. Associations between mass scores and APOL1 were assessed adjusting for age, gender, African ancestry, BMI, HbA1c, smoking, hypertension, use of statins and ACE inhibitors, albuminuria, and eGFR. Participants were 58.9% female with mean age 56.5 years, eGFR 89.5 ml/min/1.73m2, UACR 169.6 mg/g, coronary artery, carotid artery and aorta calcified plaque mass scores of 610, 171 and 5378, respectively. In fully adjusted models, APOL1 risk variants were significantly associated with lower levels of carotid artery calcified plaque (β −0.42, SE 0.18, dominant model), and marginally lower coronary artery plaque (β −0.36, SE 0.21; dominant model), but not with aorta calcified plaque, C-reactive protein, UACR, or eGFR. After a mean follow-up of 5.0 years, 89 participants died. APOL1 nephropathy risk variants were significantly associated with improved survival (hazard ratio 0.67 for 1 copy; 0.44 for 2 copies). Thus, APOL1 nephropathy variants associate with lower levels of subclinical atherosclerosis and reduced risk of death in African Americans with type 2 diabetes mellitus.
PMCID: PMC4281283  PMID: 25054777
African Americans; apolipoprotein L1 gene (APOL1); atherosclerosis; calcified atherosclerotic plaque; diabetes mellitus; kidney disease
23.  Predictors of all-cause and cardiovascular disease mortality in type 2 diabetes: Diabetes Heart Study 
Many studies evaluated the best predictors for cardiovascular disease (CVD) events in individuals with type 2 diabetes (T2D), but few studies examined the factors most strongly associated with mortality in T2D. The Diabetes Heart Study (DHS), an intensively phenotyped family-based cohort enriched for T2D, provided an opportunity to address this question.
Associations with mortality were examined in 1022 European Americans affected by T2D from 476 DHS families. All-cause mortality was 31.2 % over an average 9.6 years of follow-up. Cox proportional hazards models with sandwich-based variance estimation were used to evaluate associations between all-cause and CVD mortality and 24 demographic and clinical factors, including coronary artery calcified plaque (CAC), carotid artery intima-media thickness, medications, body mass index, waist hip ratio, lipids, blood pressure, kidney function, QT interval, educational attainment, and glycemic control. Nominally significant factors (p < 0.25) from univariate analyses were included in model selection (backward elimination, forward selection, and stepwise selection). Age and sex were included in all models.
The all-cause mortality model selected from the full DHS sample included age, sex, CAC, urine albumin: creatinine ratio (UACR), insulin use, current smoking, and educational attainment. The CVD mortality model selected from the full sample included age, sex, CAC, UACR, triglycerides, and history of CVD events. Beyond age, the most significant associations for both mortality models were CAC (2.03 × 10−4 ≤ p ≤ 0.001) and UACR (1.99 × 10−8 ≤ p ≤ 2.23 × 10−8). To confirm the validity of the main predictors identified with model selection using the full sample, a two-fold cross-validation approach was used, and similar results were observed.
This analysis highlights important demographic and clinical factors, notably CAC and albuminuria, which predict mortality in the general population of patients with T2D.
Electronic supplementary material
The online version of this article (doi:10.1186/s13098-015-0055-y) contains supplementary material, which is available to authorized users.
PMCID: PMC4490739  PMID: 26146522
Type 2 diabetes; Mortality; Coronary artery calcified plaque; Urine albumin:creatinine ratio
24.  Relevance of the ACTN4 gene in African Americans with non-diabetic ESRD 
American journal of nephrology  2012;36(3):252-260.
African Americans (AAs) are predisposed to non-diabetic (non-DM) end-stage renal disease (ESRD) and studies have shown a genetic component to this risk. Rare mutations in ACTN4 (α-actinin-4) an actin binding protein expressed in podocytes cause familial focal segmental glomerulosclerosis.
We assessed the contribution of coding variants in ACTN4 to non-DM ESRD risk in AAs. Nineteen exons, 2800 bases of the promoter and 392 bases of the 3’ untranslated region of ACTN4 were sequenced in 96 AA non-DM ESRD cases and 96 non-nephropathy controls (384 chromosomes). Sixty-seven single nucleotide polymorphisms (SNPs) including 51 novel SNPs were identified. The SNPs comprised 33 intronic, 21 promoter, 12 exonic, and 1 3’ variant. Sixty-two of the SNPs were genotyped in 296 AA non-DM ESRD cases and 358 non-nephropathy controls.
One SNP, rs10404257, was associated with non-DM ESRD (p<1.0E-4, odds ratio (OR)=0.76, confidence interval (CI)=0.59–0.98; additive model). Forty-seven SNPs had minor allele frequencies less than 5%. These SNPs were segregated into risk and protective SNPs and each category was collapsed into a single marker, designated by the presence or absence of any rare allele. The presence of any rare allele at a risk SNP was significantly associated with non-DM ESRD (p = 0.001, dominant model). The SNPs with the strongest evidence for association (n = 20) were genotyped in an independent set of 467 non-DM ESRD cases and 279 controls. Although, rs10404257 was not associated in this replication sample, when the samples were combined rs10404257 was modestly associated (p=0.032, OR=0.78, CI=0.63–0.98; dominant model). SNPs were tested for interaction with markers in the APOL1 gene, previously associated with non-DM ESRD in AAs and rs10404257 was modestly associated (p = 0.0261, additive model).
This detailed evaluation of ACTN4 variation revealed limited evidence of association with non-DM ESRD in AAs.
PMCID: PMC3510331  PMID: 22965004
ACTN4; non-diabetic ESRD; FSGS; kidney; hypertensive nephrosclerosis; African Americans
25.  β-Cell Failure in Type 2 Diabetes: Postulated Mechanisms and Prospects for Prevention and Treatment 
Diabetes Care  2014;37(6):1751-1758.
This article examines the foundation of β-cell failure in type 2 diabetes (T2D) and suggests areas for future research on the underlying mechanisms that may lead to improved prevention and treatment.
A group of experts participated in a conference on 14–16 October 2013 cosponsored by the Endocrine Society and the American Diabetes Association. A writing group prepared this summary and recommendations.
The writing group based this article on conference presentations, discussion, and debate. Topics covered include genetic predisposition, foundations of β-cell failure, natural history of β-cell failure, and impact of therapeutic interventions.
β-Cell failure is central to the development and progression of T2D. It antedates and predicts diabetes onset and progression, is in part genetically determined, and often can be identified with accuracy even though current tests are cumbersome and not well standardized. Multiple pathways underlie decreased β-cell function and mass, some of which may be shared and may also be a consequence of processes that initially caused dysfunction. Goals for future research include to 1) impact the natural history of β-cell failure; 2) identify and characterize genetic loci for T2D; 3) target β-cell signaling, metabolic, and genetic pathways to improve function/mass; 4) develop alternative sources of β-cells for cell-based therapy; 5) focus on metabolic environment to provide indirect benefit to β-cells; 6) improve understanding of the physiology of responses to bypass surgery; and 7) identify circulating factors and neuronal circuits underlying the axis of communication between the brain and β-cells.
PMCID: PMC4179518  PMID: 24812433

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