A Genome-Wide Association Study Using a Custom Genotyping Array Identifies Variants in GPR158 Associated With Reduced Energy Expenditure in American Indians

Transcriptional profiles analysis of effects of Toxoplasma gondii rhoptry protein 16 on THP-1 macrophages

Introduction

Toxoplasma gondii, an intracellular parasitic protozoan, is globally recognized for its ability to cause parasitic diseases and has developed diverse strategies to evade immune-mediated elimination. The protein ROP16 of T.gondii plays a crucial role in this evasion process by specifically targeting macrophages and mononuclear phagocytes in vivo. However, the precise mechanisms underlying the involvement of type II ROP16 proteins in infection, inflammation, and other processes remain unknown.

Methods

To investigate the mechanism of action of gonococcal ROP16 proteins in human macrophages, we constructed a lentivirus overexpressing ROP16 and established stably transfected cell lines. We then analyzed the gene transcriptional profiles of ROP16 II in THP-1 macrophages using transcriptome sequencing. Interaction networks were constructed by screening differentially expressed genes and performing gene function enrichment analysis.

Results

As a result, five differentially expressed genes were identified: AAMDC, GPR158, RAD9A, STOML1, and STRA13. Immuno-featured differential analysis showed that type 17 T helper cells were more strongly correlated with GPR158 and STRA13, while CD8 T-cell was most strongly correlated with STOML1.

Discussion

Therefore, we conclude that the ROP16 protein plays a pivotal role in THP-1 macrophage infection and these five differentially expressed genes may serve as promising molecular targets for the prevention or control of toxoplasmosis. These findings have significant implications for the diagnosis and treatment of toxoplasmosis.

Pleiotropic Effects of an eQTL in the CELSR2/PSRC1/SORT1 Cluster That Associates With LDL-C and Resting Metabolic Rate

CONTEXT

The locus CELSR2-PSRC1-SORT1, a primary genetic signal for lipids, has recently been implicated in different metabolic processes. Our investigation identified its association with energy metabolism.

OBJECTIVE

This work aimed to determine biological mechanisms that govern diverse functions of this locus.

METHODS

Genotypes for 491 265 variants in 7000 clinically characterized American Indians were previously determined using a custom-designed array specific for this longitudinally studied American Indian population. Among the genotyped individuals, 5205 had measures of fasting lipid levels and 509 had measures of resting metabolic rate (RMR) and substrate oxidation rate assessed through indirect calorimetry. A genome-wide association study (GWAS) for low-density lipoprotein cholesterol (LDL-C) levels identified a variant in CELSR2, and the molecular effect of this variant on gene expression was assessed in skeletal muscle biopsies from 207 participants, followed by functional validation in mouse myoblasts using a luciferase assay.

RESULTS

A GWAS in American Indians identified rs12740374 in CELSR2 as the top signal for LDL-C levels (P = 1 × 10-22); further analysis of this variant identified an unexpected correlation with reduced RMR (effect = -44.3 kcal/day/minor-allele) and carbohydrate oxidation rate (effect = -5.21 mg/hour/kg-EMBS). Tagged variants showed a distinct linkage disequilibrium architecture in American Indians, highlighting a potential functional variant, rs6670347 (minor-allele frequency = 0.20). Positioned in the glucocorticoid receptor's core binding motif, rs6670347 is part of a skeletal muscle-specific enhancer. Human skeletal muscle transcriptome analysis showed CELSR2 as the most differentially expressed gene (P = 1.9 × 10-7), with the RMR-lowering minor allele elevating gene expression. Experiments in mouse myoblasts confirmed enhancer-based regulation of CELSR2 expression, dependent on glucocorticoids. Rs6670347 was also associated with increased oxidative phosphorylation gene expression; CELSR2, as a regulator of these genes, suggests a potential influence on energy metabolism through muscle oxidative capacity.

CONCLUSION

Variants in the CELSR2/PSRC1/SORT1 locus exhibit tissue-specific effects on metabolic traits, with an independent role in muscle metabolism through glucocorticoid signaling.

Modulating vertebrate physiology by genomic fine-tuning of GPCR functions

G protein-coupled receptors (GPCRs) play a crucial role as membrane receptors, facilitating the communication of eukaryotic species with their environment and regulating cellular and organ interactions. Consequently, GPCRs hold immense potential in contributing to adaptation to ecological niches and responding to environmental shifts. Comparative analyses of vertebrate genomes reveal patterns of GPCR gene loss, expansion, and signatures of selection. Integrating these genomic data with insights from functional analyses of gene variants enables the interpretation of genotype-phenotype correlations. This review underscores the involvement of GPCRs in adaptive processes, presenting numerous examples of how alterations in GPCR functionality influence vertebrate physiology or, conversely, how environmental changes impact GPCR functions. The findings demonstrate that modifications in GPCR function contribute to adapting to aquatic, arid, and nocturnal habitats, influencing camouflage strategies, and specializing in particular dietary preferences. Furthermore, the adaptability of GPCR functions provides an effective mechanism in facilitating past, recent, or ongoing adaptations in animal domestication and human evolution and should be considered in therapeutic strategies and drug development.

Epistasis Between HLA-DRB1*16:02:01 and SLC16A11 T-C-G-T-T Reduces Odds for Type 2 Diabetes in Southwest American Indians

We sought to identify genetic/immunologic contributors of type 2 diabetes (T2D) in an indigenous American community by genotyping all study participants for both high-resolution HLA-DRB1 alleles and SLC16A11 to test their risk and/or protection for T2D. These genes were selected based on independent reports that HLA-DRB1*16:02:01 is protective for T2D and that SLC16A11 associates with T2D in individuals with BMI <35 kg/m2. Here, we test the interaction of the two loci with a more complete data set and perform a BMI sensitivity test. We defined the risk protection haplotype of SLC16A11, T-C-G-T-T, as allele 2 of a diallelic genetic model with three genotypes, SLC16A11*11, *12, and *22, where allele 1 is the wild type. Both earlier findings were confirmed. Together in the same logistic model with BMI ≥35 kg/m2, DRB1*16:02:01 remains protective (odds ratio [OR] 0.73), while SLC16A11 switches from risk to protection (OR 0.57 [*22] and 0.78 [*12]); an added interaction term was statistically significant (OR 0.49 [*12]). Bootstrapped (b = 10,000) statistical power of interaction, 0.4801, yielded a mean OR of 0.43. Sensitivity analysis demonstrated that the interaction is significant in the BMI range of 30-41 kg/m2. To investigate the epistasis, we used the primary function of the HLA-DRB1 molecule, peptide binding and presentation, to search the entire array of 15-mer peptides for both the wild-type and ancient human SLC16A11 molecules for a pattern of strong binding that was associated with risk and protection for T2D. Applying computer binding algorithms suggested that the core peptide at SLC16A11 D127G, FSAFASGLL, might be key for moderating risk for T2D with potential implications for type 1 diabetes.

ARTICLE HIGHLIGHTS

Novel signals and polygenic score for height are associated with pubertal growth traits in Southwestern American Indians

Most genetic variants associated with adult height have been identified through large genome-wide association studies (GWASs) in European-ancestry cohorts. However, it is unclear how these variants influence linear growth during adolescence. This study uses anthropometric and genotypic data from a longitudinal study conducted in an American Indian community in Arizona between 1965-2007. Growth parameters (i.e. height, velocity, and timing of growth spurt) were derived from the Preece-Baines growth model, a parametric growth curve fitted to longitudinal height data, in 787 participants with height measurements spanning the whole period of growth. Heritability estimates suggested that genetic factors could explain 25% to 71% of the variance of pubertal growth traits. We performed a GWAS of growth parameters, testing their associations with 5 077 595 imputed or directly genotyped variants. Six variants associated with height at peak velocity (P < 5 × 10-8, adjusted for sex, birth year and principal components). Implicated genes include NUDT3, previously associated with adult height, and PACSIN1. Two novel variants associated with duration of growth spurt (P < 5 × 10-8) in LOC105375344, an uncharacterized gene with unknown function. We finally examined the association of growth parameters with a polygenic score for height derived from 9557 single nucleotide polymorphisms (SNPs) identified in the GIANT meta-analysis for which genotypic data were available for the American Indian study population. Height polygenic score was correlated with the magnitude and velocity of height growth that occurred before and at the peak of the adolescent growth spurt, indicating overlapping genetic architecture, with no influence on the timing of adolescent growth.

Determinants of obesity in Latin America

Obesity rates are increasing almost everywhere in the world, although the pace and timing for this increase differ when populations from developed and developing countries are compared. The sharp and more recent increase in obesity rates in many Latin American countries is an example of that and results from regional characteristics that emerge from interactions between multiple factors. Aware of the complexity of enumerating these factors, we highlight eight main determinants (the physical environment, food exposure, economic and political interest, social inequity, limited access to scientific knowledge, culture, contextual behaviour and genetics) and discuss how they impact obesity rates in Latin American countries. We propose that initiatives aimed at understanding obesity and hampering obesity growth in Latin America should involve multidisciplinary, global approaches that consider these determinants to build more effective public policy and strategies, accounting for regional differences and disease complexity at the individual and systemic levels.

Effects of the ABCC8 R1420H loss-of-function variant on beta-cell function, diabetes incidence, and retinopathy

INTRODUCTION

The ABCC8 gene regulates insulin secretion and plays a critical role in glucose homeostasis. The effects of an ABCC8 R1420H loss-of-function variant on beta-cell function, incidence of type 2 diabetes, and age-at-onset, prevalence, and progression of diabetes complications were assessed in a longitudinal study in American Indians.

RESEARCH DESIGN AND METHODS

We analyzed beta-cell function through the relationship between insulin secretion and insulin sensitivity in members of this population without diabetes aged ≥5 years using standard major axis regression. We used hierarchical logistic regression models to study cross-sectional associations with diabetes complications including increased albuminuria (albumin-to-creatinine ratio (ACR) ≥30 mg/g), severe albuminuria (ACR ≥300 mg/g), reduced estimated glomerular filtration rate (eGFR <60 mL/min/1.73 m2), and retinopathy. This study included 7675 individuals (254 variant carriers) previously genotyped for the R1420H with available phenotypic data and with a median follow-up time of 13.5 years (IQR 4.5-26.8).

RESULTS

Variant carriers had worse beta-cell function than non-carriers (p=0.0004; on average estimated secretion was 22% lower, in carriers), in children and adults, with no difference in insulin sensitivity (p=0.50). At any body mass index and age before 35 years, carriers had higher type 2 diabetes incidence. This variant did not associate with prevalence of increased albuminuria (OR 0.87, 95% CI 0.66 to 1.16), severe albuminuria (OR 0.96, 95% CI 0.55 to 1.68), or reduced eGFR (OR 0.44, 95% CI 0.18 to 1.06). By contrast, the variant significantly associated with higher retinopathy prevalence (OR 1.74, 95% CI 1.19 to 2.53) and this association was only partially mediated (<11%) by glycemia, duration of diabetes, risk factors of retinopathy, or insulin use. Retinopathy prevalence in carriers was higher regardless of diabetes presence.

CONCLUSIONS

The ABCC8 R1420H variant is associated with increased risks of diabetes and of retinopathy, which may be partially explained by higher glycemia levels and worse beta-cell function.

The utility of a type 2 diabetes polygenic score in addition to clinical variables for prediction of type 2 diabetes incidence in birth, youth and adult cohorts in an Indigenous study population

AIMS/HYPOTHESIS

There is limited information on how polygenic scores (PSs), based on variants from genome-wide association studies (GWASs) of type 2 diabetes, add to clinical variables in predicting type 2 diabetes incidence, particularly in non-European-ancestry populations.

METHODS

For participants in a longitudinal study in an Indigenous population from the Southwestern USA with high type 2 diabetes prevalence, we analysed ten constructions of PS using publicly available GWAS summary statistics. Type 2 diabetes incidence was examined in three cohorts of individuals without diabetes at baseline. The adult cohort, 2333 participants followed from age ≥20 years, had 640 type 2 diabetes cases. The youth cohort included 2229 participants followed from age 5-19 years (228 cases). The birth cohort included 2894 participants followed from birth (438 cases). We assessed contributions of PSs and clinical variables in predicting type 2 diabetes incidence.

RESULTS

Of the ten PS constructions, a PS using 293 genome-wide significant variants from a large type 2 diabetes GWAS meta-analysis in European-ancestry populations performed best. In the adult cohort, the AUC of the receiver operating characteristic curve for clinical variables for prediction of incident type 2 diabetes was 0.728; with the PS, 0.735. The PS's HR was 1.27 per SD (p=1.6 × 10-8; 95% CI 1.17, 1.38). In youth, corresponding AUCs were 0.805 and 0.812, with HR 1.49 (p=4.3 × 10-8; 95% CI 1.29, 1.72). In the birth cohort, AUCs were 0.614 and 0.685, with HR 1.48 (p=2.8 × 10-16; 95% CI 1.35, 1.63). To further assess the potential impact of including PS for assessing individual risk, net reclassification improvement (NRI) was calculated: NRI for the PS was 0.270, 0.268 and 0.362 for adult, youth and birth cohorts, respectively. For comparison, NRI for HbA1c was 0.267 and 0.173 for adult and youth cohorts, respectively. In decision curve analyses across all cohorts, the net benefit of including the PS in addition to clinical variables was most pronounced at moderately stringent threshold probability values for instituting a preventive intervention.

CONCLUSIONS/INTERPRETATION

This study demonstrates that a European-derived PS contributes significantly to prediction of type 2 diabetes incidence in addition to information provided by clinical variables in this Indigenous study population. Discriminatory power of the PS was similar to that of other commonly measured clinical variables (e.g. HbA1c). Including type 2 diabetes PS in addition to clinical variables may be clinically beneficial for identifying individuals at higher risk for the disease, especially at younger ages.

Identification and characterization of the long non-coding RNA NFIA-AS2 as a novel locus for body mass index in American Indians

BACKGROUND

Genome-wide association studies have shown that body mass index (BMI), an estimate of obesity, is highly polygenic. Individual variants typically have small effect sizes, making it challenging to identify unique loci in under-represented ethnic groups which lack statistical power due to their small sample size. Yet obesity is a major health disparity and is particularly prevalent in southwestern American Indians. Here, we identify and characterize a new locus for BMI that was detected by analyzing moderate associations with BMI obtained in a population-based sample of southwestern American Indians together with the well-powered GIANT dataset.

METHODS

Genotypes for 10.5 million variants were tested for association with BMI in 5870 American Indians and 2600 variants that showed an association P < 10^-3 in the American Indian sample were combined in a meta-analysis with the BMI data reported in GIANT (N = 240,608). The newly identified gene, NFIA-AS2 was functionally characterized, and the impact of its lead associated variant rs1777538 was studied both in-silico and in-vitro.

RESULTS

Rs1777538 (T/C; C allele frequency = 0.16 in American Indians and 0.04 in GIANT, meta-analysis P = 5.0 × 10^-7) exhibited a large effect in American Indians (1 kg/m² decrease in BMI per copy of C allele). NFIA-AS2 was found to be a nuclear localized long non-coding RNA expressed in tissues pertinent to human obesity. Analysis of this variant in human brown preadipocytes showed that NFIA-AS2 transcripts carrying the C allele had increased RNA degradation compared to the T allele transcripts (half-lives = 9 h, 13 h respectively). During brown adipogenesis, NFIA-AS2 featured a stage-specific regulation of nearby gene expression where rs1777538 demonstrated an allelic difference in regulation in the mature adipocytes (the strongest difference was observed for L1TD1, P = 0.007).

CONCLUSION

Our findings support a role for NFIA-AS2 in regulating pathways that impact BMI.

The emerging roles of GPR158 in the regulation of the endocrine system

G protein-coupled receptor 158 (GPR158) is a member of class C G protein-coupled receptors (GPCRs) and is highly expressed in the central nervous system (CNS) while lowly expressed in peripheral tissues. Previous studies have mainly focused on its functions in the CNS, such as regulating emotions, memory, and cognitive functions, whereas studies on its role in the non-nervous system are limited. It has been recently reported that GPR158 is directly involved in adrenal regulation, suggesting its role in peripheral tissues. Moreover, GPR158 is a stable dimer coupled to the regulator of G protein signaling protein 7 (RGS7) that forms the GPR158-RGS7-Gβ5 complex. Given that the RGS7-Gβ5 complex is implicated in endocrine functions, we speculate that GPR158 might be an active component of the endocrine system. Herein, we reviewed the relevant literature on GPR158, including its molecular structure, regulatory molecules, expression, and functions, and highlighted its roles in endocrine regulation. These findings not only enhance our understanding of GPR158 from an endocrine perspective but also provide valuable insights into drug exploration targeting GPR158 and their applicability in endocrine disorders.

Research Status of the Orphan G Protein Coupled Receptor 158 and Future Perspectives

G-protein-coupled receptors (GPCRs) remain one of the most successful targets for therapeutic drugs approved by the US Food and Drug Administration (FDA). Many novel orphan GPCRs have been identified by human genome sequencing and considered as putative targets for refractory diseases. Of note, a series of studies have been carried out involving GPCR 158 (or GPR158) since its identification in 2005, predominantly focusing on the characterization of its roles in the progression of cancer and mental illness. However, advances towards an in-depth understanding of the biological mechanism(s) involved for clinical application of GPR158 are lacking. In this paper, we clarify the origin of the GPR158 evolution in different species and summarize the relationship between GPR158 and different diseases towards potential drug target identification, through an analysis of the sequences and substructures of GPR158. Further, we discuss how recent studies set about unraveling the fundamental features and principles, followed by future perspectives and thoughts, which may lead to prospective therapies involving GPR158.

Serum Level of Polyubiquitinated PTEN and Loss of Kidney Function in American Indians With Type 2 Diabetes

RATIONALE & OBJECTIVE

Fibrosis is a major driver of chronic kidney disease, and epithelial-mesenchymal transition (EMT) may contribute to its development. A polyubiquitinated form of phosphatase and tensin homolog (PTEN^K27polyUb) promotes EMT in vitro. Thus, it is a potentially useful biomarker of progressive kidney fibrosis and may predict loss of kidney function.

STUDY DESIGN

Observational cohort study.

SETTING & PARTICIPANTS

Southwest United States, American Indians (154 women, 80 men) with or at high risk for diabetic kidney disease (DKD).

PREDICTORS

Serum level of PTEN^K27polyUb.

OUTCOME

≥40% loss of glomerular filtration rate (GFR) or onset of kidney failure. Kidney structural measures in a subset of study participants who underwent research kidney biopsies (n = 77).

ANALYTICAL APPROACH

Cox proportional hazards models adjusted for age, sex, diabetes duration, hemoglobin A_1c (HbA_1c), blood pressure, use of renin angiotensin system (RAS) blockers, measured GFR, and albuminuria. Spearman correlations for associations with structural measures.

RESULTS

At baseline, the participants' mean age was 42.8 ± 10.5 (SD) years, diabetes duration 11.5 ± 7.1 years, mean arterial pressure 90.5 ± 9.5 mm Hg, HbA_1c 9.3 ± 2.4%, GFR 152 ± 45 mL/min, and median urinary albumin-creatinine ratio 38 (interquartile range, 14-215) mg/g. RAS blockers were being used by 64 participants (27.4%). A higher PTEN^K27polyUb value was associated with a greater risk of ≥40% loss of GFR during a median follow-up period of 6.3 years (HR for quartile 4 [Q4] vs Q1, 3.95 [95% CI, 2.23-6.98], P < 0.001). Serum PTEN^K27polyUb was associated with an increased risk of kidney failure over a median follow-up period of 15.8 years (HR for Q4 vs Q1, 5.66 [95% CI, 1.99-16.13], P = 0.001). Baseline serum PTEN^K27polyUb in the biopsy subset correlated with structural measures including glomerular basement membrane width (ρ = 0.370, P < 0.001) and mesangial fractional volume (ρ = 0.392, P < 0.001).

LIMITATIONS

Small study in single population.

CONCLUSIONS

Higher serum PTEN^K27polyUb is associated with increased risk for GFR decline and kidney failure in American Indians with type 2 diabetes.

The counterbalancing effects of energy expenditure on body weight regulation: Orexigenic versus energy-consuming mechanisms

OBJECTIVE

Weight change is a dynamic function of whole-body energy balance resulting from the interplay between energy intake and energy expenditure (EE). Recent reports have provided evidence for the existence of a causal effect of EE on energy intake, suggesting that increased EE may drive overeating, thereby promoting future weight gain. This study investigated the relationships between ad libitum energy intake and 24-hour EE (24-h EE) in sedentary conditions versus long-term, free-living weight change using a mediation analysis framework.

METHODS

Native American individuals (n = 61, body fat by dual-energy x-ray absorptiometry: 39.7% [SD 9.5%]) were admitted to the clinical inpatient unit and had baseline measurements as follows: 1) 24-h EE accurately measured in a whole-room indirect calorimeter during energy balance and weight stability; and 2) ad libitum energy intake objectively assessed for 3 days using computerized vending machines. Free-living weight change was assessed after a median follow-up time of 1.7 years (interquartile range: 1.2-2.9).

RESULTS

The total effect of 24-h EE on weight change (-0.23 kg per 100-kcal/d difference in EE at baseline) could be partitioned into the following two independent and counterbalanced effects: higher EE protective against weight gain (-0.46 kg per 100-kcal/d difference in EE at baseline) and an orexigenic effect promoting overeating, thereby favoring weight gain (+0.23 kg per 100-kcal/d difference in EE at baseline).

CONCLUSIONS

The overall impact of EE on body weight regulation should be evaluated by also considering its collateral effect on energy intake. Any weight loss intervention aimed to induce energy deficits by increasing EE should take into account any potential orexigenic effects that promote compensatory overeating, thereby limiting the efficacy of these obesity therapies.

Functional variants in cytochrome b5 type A (CYB5A) are enriched in Southwest American Indian individuals and associate with obesity

OBJECTIVE

This study aimed to identify genetic variants enriched in Southwest American Indian (SWAI) individuals that associate with BMI.

METHODS

Whole genome sequencing data (n = 296) were used to identify potentially functional variants that are common in SWAI individuals (minor allele frequency ≥10%) but rare in other ethnic groups (minor allele frequency < 0.1%). Enriched variants were tested for association with BMI in 5,870 SWAI individuals. One variant was studied using a luciferase reporter, and haplotypes that included this variant were analyzed for association with various measures of obesity (n = 917-5,870), 24-hour energy expenditure (24-h EE; n = 419), and skeletal muscle biopsy expression data (n = 207).

RESULTS

A 5' untranslated region variant in cytochrome b5 type A (CYB5A), rs548402150, met the enrichment criteria and associated with increased BMI (β = 2%, p = 0.004). Functionally, rs548402150 decreased luciferase expression by 30% (p = 0.003) and correlated with decreased skeletal muscle CYB5A expression (β = -0.5 SD, p = 0.0008). Combining rs548402150 with two splicing quantitative trait loci in CYB5A identified a haplotype carried almost exclusively in SWAI individuals that associated with increased BMI (β = 3%, p = 0.0003) and decreased CYB5A expression, whereas the most common haplotype in all ethnic groups associated with lower BMI and percentage of body fatness, increased 24-h EE, and increased CYB5A expression.

CONCLUSIONS

Further studies on the effects of CYB5A on 24-h EE and BMI may provide insights into obesity-related physiology.

Integrating genetics, physiology and morphology to study desert adaptation in a lizard species

Integration of multiple approaches is key to understand the evolutionary processes of local adaptation and speciation. Reptiles have successfully colonized desert environments, that is, extreme and arid conditions that constitute a strong selective pressure on organisms. Here, we studied genomic, physiological and morphological variations of the lizard Liolaemus fuscus to detect adaptations to the Atacama Desert. By comparing populations of L. fuscus inhabiting the Atacama Desert with populations from the Mediterranean forests from central Chile, we aimed at characterizing features related to desert adaptation. We combined ddRAD sequencing with physiological (evaporative water loss, metabolic rate and selected temperature) and morphological (linear and geometric morphometrics) measurements. We integrated the genomic and phenotypic data using redundancy analyses. Results showed strong genetic divergence, along with a high number of fixed loci between desert and forest populations. Analyses detected 110 fixed and 30 outlier loci located within genes, from which 43 were in coding regions, and 12 presented non-synonymous mutations. The candidate genes were associated with cellular membrane and development. Desert lizards presented lower evaporative water loss than those from the forest. Morphological data showed that desert lizards had smaller body size, different allometry, larger eyeballs and more dorsoventrally compressed heads. Our results suggest incipient speciation between desert and forest populations. The adaptive signal must be cautiously interpreted since genetic drift could also contribute to the divergence pattern. Nonetheless, we propose water and resource availability, and changes in habitat structure, as the most relevant challenges for desert reptiles. This study provides insights of the mechanisms that allow speciation as well as desert adaptation in reptiles at multiple levels, and highlights the benefit of integrating independent evidence.

Exome Sequencing Identifies A Nonsense Variant in DAO Associated With Reduced Energy Expenditure in American Indians

BACKGROUND

Obesity and energy expenditure (EE) are heritable and genetic variants influencing EE may contribute to the development of obesity. We sought to identify genetic variants that affect EE in American Indians, an ethnic group with high prevalence of obesity.

METHODS

Whole-exome sequencing was performed in 373 healthy Pima Indians informative for 24-hour EE during energy balance. Genetic association analyses of all high-quality exonic variants (≥5 carriers) was performed, and those predicted to be damaging were prioritized.

RESULTS

Rs752074397 introduces a premature stop codon (Cys264Ter) in DAO and demonstrated the strongest association for 24-hour EE, where the Ter allele associated with substantially lower 24-hour EE (mean lower by 268 kcal/d) and sleeping EE (by 135 kcal/d). The Ter allele has a frequency = 0.5% in Pima Indians, whereas is extremely rare in most other ethnic groups (frequency < 0.01%). In vitro functional analysis showed reduced protein levels for the truncated form of DAO consistent with increased protein degradation. DAO encodes D-amino acid oxidase, which is involved in dopamine synthesis which might explain its role in modulating EE.

CONCLUSION

Our results indicate that a nonsense mutation in DAO may influence EE in American Indians. Identification of variants that influence energy metabolism may lead to new pathways to treat human obesity.

CLINICAL TRIAL REGISTRATION NUMBER

NCT00340132.

Early adaptive thermogenesis is a determinant of weight loss after six weeks of caloric restriction in overweight subjects

BACKGROUND

Adaptive thermogenesis during prolonged energy deficit refers to the greater than expected reduction in energy expenditure (EE) independent of concomitant loss of metabolically active body mass.

OBJECTIVE

As inter-individual variability in the magnitude of adaptive thermogenesis may influence the extent of energy deficit thereby predicting the amount of weight reduction, we investigated whether early adaptive thermogenesis is a determinant of weight loss after 6 weeks of daily 50% caloric restriction in an inpatient setting.

DESIGN AND METHODS

The current study reports the results of an exploratory, secondary analysis in overweight but otherwise healthy subjects (n = 11, 7 men, 35 ± 9y, BMI = 40 ± 7 kg/m², body fat = 63.3 ± 5.3%). Body composition and 24-h EE (24hEE) measurement in a whole-room indirect calorimeter were used to calculate the magnitude of adaptive thermogenesis while on caloric restriction after 1, 3 and 6 weeks. Energy deficit during caloric restriction was quantified via food, stool, and urine bomb calorimetry. Fasting hormonal concentrations (FT4, FT3, FGF21, leptin) were obtained at baseline and at weeks 3 and 6 during caloric restriction.

RESULTS

The magnitude of adaptive thermogenesis in 24hEE after 1 week of caloric restriction was -178 ± 137 kcal/day (mean ± SD), was overall stable during and following caloric restriction, and demonstrated remarkable intra-individual consistency. A relatively greater decrease in 24hEE of 100 kcal/d after 1 week of caloric restriction was associated on average with reduced energy deficit by 8195 kcal over 6 weeks and predicted 2.0 kg less weight loss, of which 0.5 kg was fat mass, after 6 weeks. No correlations were found between hormonal concentrations and weight loss.

CONCLUSIONS

The extent of weight loss is influenced by the magnitude of adaptive thermogenesis in the early stage of caloric restriction. Although these results need replication in larger study groups with adequate statistical power, targeting adaptive thermogenesis may help to optimize long-term interventions in obesity therapy.

An appraisal of whole-room indirect calorimeters and a metabolic cart for measuring resting and active metabolic rates

Whole-room indirect calorimeters (WRICs) have traditionally been used for real-time resting metabolic rate (RMR) measurements, while metabolic rate (MR) during short-interval exercises has commonly been measured by metabolic carts (MCs). This study aims to investigate the feasibility of incorporating short-interval exercises into WRIC study protocols by comparing the performance of WRICs and an MC. We assessed the 40-min RMR of 15 subjects with 2-day repeats and the 10-15 min activity MR (AMR) of 14 subjects at three intensities, using a large WRIC, a small WRIC, and an MC. We evaluated the biases between the instruments and quantified sources of variation using variance component analysis. All three instruments showed good agreement for both RMR (maximum bias = 0.07 kcal/min) and AMR assessment (maximum bias = 0.53 kcal/min). Moreover, the majority of the variability was between-subject and between-intensity variation, whereas the types of instrument contributed only a small amount to total variation in RMR (2%) and AMR (0.2%) data. In Conclusion, the good reproducibility among the instruments indicates that they may be used interchangeably in well-designed studies. Overall, WRICs can serve as an accurate and versatile means of assessing MR, capable of integrating RMR and short-interval AMR assessments into a single protocol.

Characterization of Exome Variants and Their Metabolic Impact in 6,716 American Indians from the Southwest US

Applying exome sequencing to populations with unique genetic architecture has the potential to reveal novel genes and variants associated with traits and diseases. We sequenced and analyzed the exomes of 6,716 individuals from a Southwestern American Indian (SWAI) population with well-characterized metabolic traits. We found that the SWAI population has distinct allelic architecture compared to populations of European and East Asian ancestry, and there were many predicted loss-of-function (pLOF) and nonsynonymous variants that were highly enriched or private in the SWAI population. We used pLOF and nonsynonymous variants in the SWAI population to evaluate gene-burden associations of candidate genes from European genome-wide association studies (GWASs) for type 2 diabetes, body mass index, and four major plasma lipids. We found 19 significant gene-burden associations for 11 genes, providing additional evidence for prioritizing candidate effector genes of GWAS signals. Interestingly, these associations were mainly driven by pLOF and nonsynonymous variants that are unique or highly enriched in the SWAI population. Particularly, we found four pLOF or nonsynonymous variants in APOB, APOE, PCSK9, and TM6SF2 that are private or enriched in the SWAI population and associated with low-density lipoprotein (LDL) cholesterol levels. Their large estimated effects on LDL cholesterol levels suggest strong impacts on protein function and potential clinical implications of these variants in cardiovascular health. In summary, our study illustrates the utility and potential of exome sequencing in genetically unique populations, such as the SWAI population, to prioritize candidate effector genes within GWAS loci and to find additional variants in known disease genes with potential clinical impact.

Associations of nicotidamide-N-methyltransferase, FTO, and IRX3 genetic variants with body mass index and resting energy expenditure in Mexican subjects

The enzyme nicotidamide-N-methyltransferase (NNMT) regulates adipose tissue energy expenditure through increasing nicotinamide adenosine dinucleotide (NAD⁺) content. NNMT methylates nicotinamide to N¹-methylnicotidamide (MNA-1) using S-adenosyl methionine. The rs694539 NNMT polymorphism is associated with non-alcoholic steatohepatitis, and rs1941404 is associated with hyperlipidemia. The rs1421085 FTO is related to poor eating behaviors, and rs3751723 IRX3 is associated with obesity. To investigate the association of rs694539 and rs1941404 NNMT, rs140285 FTO and rs3751723 IRX3 polymorphisms with MNA-1 concentrations, resting energy expenditure (REE) and BMI, we included clinically healthy Mexican subjects 30 to 50 years old, 100 subjects (35 men/65 women) with BMI > 30 kg/m² and 100 subjects (32 men/68 women) with BMI < 25 kg/m². Glucose, lipid profile, insulin, leptin, acylated ghrelin, and MNA-1 (LC–MS) were quantified. Resting energy expenditure (REE) was estimated using indirect calorimetry with a Fitmate instrument. Genotyping was performed using PCR–RFLP, and allelic discrimination was examined using TaqMan probes. MNA-1 concentrations and REE were significantly higher in obese subjects. Subjects with the rs694539AA NNMT genotype (recessive model) had lower weight, BMI, and REE. BMI showed an association with HDL-C, triglycerides, MNA-1, acetylated ghrelin, leptin, insulin concentrations, HOMA-IR, REE, and rs1421085. Subjects with the TC or CC genotypes of rs1421085 FTO showed 6 kg and 2 units of BMI more than did those with the TT wild type. The CG of the rs1421085 and rs3751723 haplotypes was associated with BMI. These findings showed that BMI was strongly associated with REE, rs1421085 FTO and the CG rs1421085 FTO and rs3751723 IRX3 haplotypes. We used the GMDR approach in obesity phenotype to show the interaction of four SNPs and metabolic variables.

Low Serum Insulinlike Growth Factor II Levels Correlate with High BMI in American Indian Adults

OBJECTIVE

Insulinlike growth factor II (IGF-II) regulates metabolism and growth. In humans, both positive and negative relationships have been reported between serum IGF-II levels and obesity. This study assessed the relationship between serum IGF-II levels and BMI and determined whether IGF-II levels predict weight gain.

METHODS

Serum samples were available from 911 American Indians with a recorded BMI. IGF-II was measured using enzyme-linked immunosorbent assay.

RESULTS

Serum IGF-II levels were negatively correlated with BMI (r = -0.17, P = 4.4 × 10^-7 , adjusted for age, sex, and storage time). The strongest correlation was in participants aged ≥ 30 years (r = -0.28, P = 3.4 × 10^-8 , N = 349), a modest correlation was in participants aged 20 to 29 years (r = -0.15, P = 7.6 × 10^-3 , N = 322), and participants aged 15 to 19 years had no correlation (r = 0.05, P = 0.48, N = 240). IGF-II levels did not predict weight gain. However, among individuals who had genotypes for 64 established obesity variants (age ≥ 20 years, N = 671), a genetic risk score for high BMI was associated with lower IGF-II (β = -0.08 SD of IGF-II per SD of the genetic risk score, P = 0.025).

CONCLUSIONS

There is a negative relationship between IGF-II levels and BMI, in which the correlation is stronger at older ages. The association between genetic risk for BMI and IGF-II levels suggests that this correlation may be due to an effect of obesity on IGF-II.

Protocol for DNA Microarrays on Glass Slides

The DNA microarray is a powerful, flexible, nonbiased discovery technology. Microarrays can be used to assess processes from gene expression to long noncoding RNAs to specific pathologies, as well as many others. This chapter describes the protocol for DNA microarray analysis of differential gene expression using DNA sequences spotted on microscope slides.

Birthweight and early-onset type 2 diabetes in American Indians: differential effects in adolescents and young adults and additive effects of genotype, BMI and maternal diabetes

AIMS/HYPOTHESIS

The aim of this work was to estimate the impact of birthweight on early-onset (age <40 years) type 2 diabetes.

METHODS

A longitudinal study of American Indians, aged ≥5 years, was conducted from 1965 to 2007. Participants who had a recorded birthweight were followed until they developed diabetes or their last examination before the age of 40 years, whichever came first. Age- and sex-adjusted diabetes incidence rates were computed and Poisson regression was used to model the effect of birthweight on diabetes incidence, adjusted for sex, BMI, a type 2 diabetes susceptibility genetic risk score (GRS) and maternal covariates.

RESULTS

Among 3039 participants, there were 652 incident diabetes cases over a median follow-up of 14.3 years. Diabetes incidence increased with age and was greater in the lowest and highest quintiles of birthweight. Adjusted for covariates, the effect of birthweight on diabetes varied over time, with a non-linear effect at 10-19 years (p < 0.001) and a negative linear effect at older age intervals (20-29 years, p < 0.001; 30-39 years, p = 0.003). Higher GRS, greater BMI and maternal diabetes had additive but not interactive effects on the association between birthweight and diabetes incidence.

CONCLUSIONS/INTERPRETATION

In this high-risk population, both low and high birthweights were associated with increased type 2 diabetes risk in adolescence (age 10-19 years) but only low birthweight was associated with increased risk in young adulthood (20-39 years). Higher type 2 diabetes GRS, greater BMI and maternal diabetes added to the risk of early-onset diabetes.

Etiopathogenetic Mechanisms in Diverticular Disease of the Colon

This article reviews epidemiological evidence of heritability and putative mechanisms in diverticular disease, with greatest attention to 3 recent studies of genetic associations with diverticular disease based on genome-wide or whole-genome sequencing studies in large patient cohorts. We provide an analysis of the biological plausibility of the significant associations with gene variants reported and highlight the relevance of ANO1, CPI-17 (aka PPP1R14A), COLQ6, COL6A1, CALCB or CALCA, COL6A1, ARHGAP15, and S100A10 to colonic neuromuscular function and tissue properties that may result in altered compliance and predispose to the development of diverticular disease. Such studies also identify candidate genes for future studies.

Host genetic determinants of the gut microbiota of wild mice

Identifying a common set of genes that mediate host-microbial interactions across populations and species of mammals has broad relevance for human health and animal biology. However, the genetic basis of the gut microbial composition in natural populations remains largely unknown outside of humans. Here, we used wild house mouse populations as a model system to ask three major questions: (a) Does host genetic relatedness explain interindividual variation in gut microbial composition? (b) Do population differences in the microbiota persist in a common environment? (c) What are the host genes associated with microbial richness and the relative abundance of bacterial genera? We found that host genetic distance is a strong predictor of the gut microbial composition as characterized by 16S amplicon sequencing. Using a common garden approach, we then identified differences in microbial composition between populations that persisted in a shared laboratory environment. Finally, we used exome sequencing to associate host genetic variants with microbial diversity and relative abundance of microbial taxa in wild mice. We identified 20 genes that were associated with microbial diversity or abundance including a macrophage-derived cytokine (IL12a) that contained three nonsynonymous mutations. Surprisingly, we found a significant overrepresentation of candidate genes that were previously associated with microbial measurements in humans. The homologous genes that overlapped between wild mice and humans included genes that have been associated with traits related to host immunity and obesity in humans. Gene-bacteria associations identified in both humans and wild mice suggest some commonality to the host genetic determinants of gut microbial composition across mammals.

Metabolic Determinants of Weight Gain in Humans

One of the fundamental challenges in obesity research is to identify subjects prone to weight gain so that obesity and its comorbidities can be promptly prevented or treated. The principles of thermodynamics as applied to human body energetics demonstrate that susceptibility to weight gain varies among individuals as a result of interindividual differences in energy expenditure and energy intake, two factors that counterbalance one another and determine daily energy balance and, ultimately, body weight change. This review focuses on the variability among individuals in human metabolism that determines weight change. Conflicting results have been reported about the role of interindividual differences in energy metabolism during energy balance in relation to future weight change. However, recent studies have shown that metabolic responses to acute, short-term dietary interventions that create energy imbalance, such as low-protein overfeeding or fasting for 24 hours, may reveal the underlying metabolic phenotype that determines the degree of resistance to diet-induced weight loss or the propensity to spontaneous weight gain over time. Metabolically "thrifty" individuals, characterized by a predilection for saving energy in settings of undernutrition and dietary protein restriction, display a minimal increase in plasma fibroblast growth factor 21 concentrations in response to a low-protein overfeeding diet and tend to gain more weight over time compared with metabolically "spendthrift" individuals. Similarly, interindividual variability in the causal relationship between energy expenditure and energy intake ("energy sensing") and in the metabolic response to cold exposure (e.g., brown adipose tissue activation) seems, to some extent, to be indicative of individual propensity to weight gain. Thus, an increased understanding and the clinical characterization of phenotypic differences in energy metabolism among individuals (metabolic profile) may lead to new strategies to prevent weight gain or improve weight-loss interventions by targeted therapies on the basis of metabolic phenotype and susceptibility to obesity in individual persons.

Multi-Ancestry Genome-Wide Association Study of Spontaneous Clearance of Hepatitis C Virus

BACKGROUND & AIMS

Spontaneous clearance of hepatitis C virus (HCV) occurs in approximately 30% of infected persons and less often in populations of African ancestry. Variants in major histocompatibility complex (MHC) and in interferon lambda genes are associated with spontaneous HCV clearance, but there have been few studies of these variants in persons of African ancestry. We performed a dense multi-ancestry genome-wide association study of spontaneous clearance of HCV, focusing on individuals of African ancestry.

METHODS

We performed genotype analyses of 4423 people from 3 ancestry groups: 2201 persons of African ancestry (445 with HCV clearance and 1756 with HCV persistence), 1739 persons of European ancestry (701 with HCV clearance and 1036 with HCV persistence), and 486 multi-ancestry Hispanic persons (173 with HCV clearance and 313 with HCV persistence). Samples were genotyped using Illumina (San Diego, CA) arrays and statistically imputed to the 1000 Genomes Project. For each ancestry group, the association of single-nucleotide polymorphisms with HCV clearance was tested by log-additive analysis, and then a meta-analysis was performed.

RESULTS

In the meta-analysis, significant associations with HCV clearance were confirmed at the interferon lambda gene locus IFNL4-IFNL3 (19q13.2) (P = 5.99 × 10-50) and the MHC locus 6p21.32 (P = 1.15 × 10-21). We also associated HCV clearance with polymorphisms in the G-protein-coupled receptor 158 gene (GPR158) at 10p12.1 (P = 1.80 × 10-07). These 3 loci had independent, additive effects of HCV clearance, and account for 6.8% and 5.9% of the variance of HCV clearance in persons of European and African ancestry, respectively. Persons of African or European ancestry carrying all 6 variants were 24-fold and 11-fold, respectively, more likely to clear HCV infection compared with individuals carrying none or 1 of the clearance-associated variants.

CONCLUSIONS

In a meta-analysis of data from 3 studies, we found variants in MHC genes, IFNL4-IFNL3, and GPR158 to increase odds of HCV clearance in patients of European and African ancestry. These findings could increase our understanding of immune response to and clearance of HCV infection.

A genome-wide association study of energy intake and expenditure

Excessive energy intake or insufficient energy expenditure, which result in energy imbalance, contribute to the development of obesity. Obesity-related genes, such as FTO, are associated with energy traits. No genome-wide association studies (GWAS) have been conducted to detect the genetic associations with energy-related traits, including energy intake and energy expenditure, among European-ancestry populations. In this study, we conducted a genome-wide study using pooled GWAS including 12,030 European-ancestry women and 6,743 European-ancestry men to identify genetic variants associated with these two energy traits. We observed a statistically significant genome-wide SNP heritability for energy intake of 6.05% (95%CI = (1.76, 10.34), P = 0.006); the SNP heritability for expenditure was not statistically significantly greater than zero. We discovered three SNPs on chromosome 12q13 near gene ANKRD33 that were genome-wide significantly associated with increased total energy intake among all men. We also identified signals on region 2q22 that were associated with energy expenditure among lean people. Body mass index related SNPs were found to be significantly associated with energy intake and expenditure through SNP set analyses. Larger GWAS studies of total energy traits are warranted to explore the genetic basis of energy intake, including possible differences between men and women, and the association between total energy intake and other downstream phenotypes, such as diabetes and chronic diseases.

Identification and functional analysis of a novel G310D variant in the insulin-like growth factor 1 receptor (IGF1R) gene associated with type 2 diabetes in American Indians

AIMS

Insulin-like growth factor 1 receptor (IGF1R) is involved in cell growth and glucose homeostasis. In the current study, the IGF1R locus was analysed as a candidate gene for type 2 diabetes (T2D) in American Indians.

MATERIALS AND METHODS

Whole genome sequence data from 335 American Indians identified 3 novel missense variants in IGF1R. The associations of IGF1R variants with T2D, age of T2D onset and birth weight were analysed in a population-based sample of 7701 American Indians.

RESULTS

A novel glycine-to-aspartic acid substitution (G310D) in IGF1R was identified, which associated with T2D in a sex-specific manner (P_sex interaction = 0.02). In women, the aspartic acid (D) allele (frequency = 0.034) was associated with increased risk for T2D (n = 4292, P = 2.0 × 10^-5 adjusted for age, birth year, and the first 5 genetic principal components; odds ratio [OR] = 2.23 [1.54-3.23] per risk allele) and an earlier age of T2D onset (n = 4292, P = 2 × 10^-4 , hazard rate ratio = 1.45 [1.20-1.75], P_sex interaction = 0.05). Female carriers of the D-allele also had lower birth weight (n = 1313, β = -163 g, P = .006, P_sex interaction = 0.008). Among 85 siblings discordant for G310D, carriers of the D-allele had shorter stature as compared with carriers of the G-allele (β = -1.6 cm, P = .001, within family model). The G310D variant was functionally studied in vitro, where the D-allele had a 22% increase (P = .0005) in FOXO1-induced transcriptional activity, due to decreased activation of the PI3K/AKT pathway mediated through reduced IGF1R activity.

CONCLUSION

A unique G310D variant in IGF1R, which occurs in 6% American Indians, may impair IGF1R signalling pathways, thereby increasing the risk of T2D.

Functional and association analysis of an Amerindian-derived population-specific p.(Thr280Met) variant in RBPJL, a component of the PTF1 complex

PTF1 complex is critical for pancreatic development and maintenance of adult exocrine pancreas. As a part of our ongoing studies to identify genetic variation that contributes to type 2 diabetes (T2D) in American Indians, we analyzed variation in genes that form this complex, namely PTF1A, RBPJ, and its paralogue RBPJL. A c.839C>T (p.(Thr280Met)) variant (rs200998587:C>T, risk allele frequency = 0.03) in RBPJL, identified only in Amerindian-derived populations, associated with T2D (OR = 1.60[1.21-2.13] per Met allele, P = 0.001) and age of diabetes onset (HR = 1.40[1.14-1.72], P = 0.001). Knockdown of Rbpjl in mouse pancreatic acinar cells resulted in a significant decrease in the mRNA expression of genes encoding exocrine enzymes including Ctrb. CTRB1/2 is an established T2D locus where the protective allele associates with increased GLP-1-stimulated insulin secretion and higher expression of CTRB1/2. In vitro studies show that cells expressing the Met280 allele had lower RBPJL protein levels than cells expressing the Thr280 allele, despite having comparable levels of RNA, suggesting that the Met280 RBPJL is less stable. Additionally, luciferase assays in HEK293 cells which examined two different RBPJL responsive promoters, including the promoter for CTRB1, also identified reduced transactivation by the Met280 RBPJL. Similarly, overexpression of both Met280 and Thr280 RBPJL in mouse pancreatic acinar cells identified a significant impairment in the expression of Cel when transactivated by the Met280 RBPJL. In summary, we identified a functional, Amerindian-derived population-specific c.839C>T (p.(Thr280Met)) variant in the pancreas specific RBPJL that may modify T2D risk by regulating exocrine enzyme expression.

Energy expenditure in the etiology of human obesity: spendthrift and thrifty metabolic phenotypes and energy-sensing mechanisms

The pathogenesis of human obesity is the result of dysregulation of the reciprocal relationship between food intake and energy expenditure (EE), which influences daily energy balance and ultimately leads to weight gain. According to principles of energy homeostasis, a relatively lower EE in a setting of energy balance may lead to weight gain; however, results from different study groups are contradictory and indicate a complex interaction between EE and food intake which may differentially influence weight change in humans. Recently, studies evaluating the adaptive response of one component to perturbations of the other component of energy balance have revealed both the existence of differing metabolic phenotypes ("spendthrift" and "thrifty") resulting from overeating or underfeeding, as well as energy-sensing mechanisms linking EE to food intake, which might explain the propensity of an individual to weight gain. The purpose of this review is to debate the role that human EE plays on body weight regulation and to discuss the physiologic mechanisms linking EE and food intake. An increased understanding of the complex interplay between human metabolism and food consumption may provide insight into pathophysiologic mechanisms underlying weight gain, which may eventually lead to prevention and better treatment of human obesity.

Parental history of type 2 diabetes is associated with lower resting energy expenditure in normoglycemic subjects

OBJECTIVE

Resting energy expenditure (REE) is linked to obesity, insulin resistance and type 2 diabetes (T2DM). REE and T2DM are inherited traits. Therefore, we investigated the effect of parental T2DM on REE in normoglycemic subjects.

METHODS

Eighty-seven subjects with parental T2DM and 83 subjects without parental T2DM were matched in age, gender, race, BMI, weight and waist circumference. Subjects underwent a 75 g oral glucose tolerance test; REE was determined by indirect calorimetry and body composition was assessed by dual energy X-ray absorptiometry. Statistical analysis was performed using Student's t-test, analysis of variance and regression analysis.

RESULTS

The mean age was 38.8±11.3 years, 57% were females and 53% were African-Americans. The mean BMI was 28.5±6.1 kg/m², waist circumference 91.8±15.1 cm, weight 83.9±20.3 kg, fat mass 31.0%±10.0%, mean fat-free mass (FFM) 54.4±12.9 kg. REE was significantly lower in subjects with parental diabetes, normalized REE 1364.4±263.4Kcal/day vs 1489.4±323.2 Kcal/day, p=0.006 and 29.2±5.3Kcal/kg FFM/day vs 31.9±6.0 Kcal/kg FFM/day, p=0.002. African-Americans had a lower REE compared with Caucasians 28.6±5.4Kcal/kg FFM/day vs 32.6±5.5 Kcal/kg FFM/day, p<0.0001. In a multiple regression model, ethnicity (p<0.0001), parental history of T2DM (p=0.006) and FFM (p=0.021) were independent predictors of REE.

CONCLUSION

Compared with subjects without parental diabetes, offspring with parental T2DM had lower REE, which was more pronounced in African-Americans. This metabolic alteration could increase the risk of obesity, insulin resistance and dysglycemia.