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The Ile138Met variant (rs738409) in the PNPLA3 gene has the largest effect on non-alcoholic fatty liver disease (NAFLD), increasing the risk of progression to severe forms of liver disease. It remains unknown if the variant plays a role in age of NAFLD onset. We aimed to determine if rs738409 impacts on the age of NAFLD diagnosis. We applied a novel natural language processing (NLP) algorithm to a longitudinal electronic health records (EHR) dataset of >27,000 individuals with genetic data from a multi-ethnic biobank, defining NAFLD cases (n = 1,703) and confirming controls (n = 8,119). We conducted i) a survival analysis to determine if age at diagnosis differed by rs738409 genotype, ii) a receiver operating characteristics analysis to assess the utility of the rs738409 genotype in discriminating NAFLD cases from controls, and iii) a phenome-wide association study (PheWAS) between rs738409 and 10,095 EHR-derived disease diagnoses. The PNPLA3 G risk allele was associated with: i) earlier age of NAFLD diagnosis, with the strongest effect in Hispanics (hazard ratio 1.33; 95% CI 1.15–1.53; p <0.0001) among whom a NAFLD diagnosis was 15% more likely in risk allele carriers vs. non-carriers; ii) increased NAFLD risk (odds ratio 1.61; 95% CI 1.349–1.73; p <0.0001), with the strongest effect among Hispanics (odds ratio 1.43; 95% CI 1.28–1.59; p <0.0001); iii) additional liver diseases in a PheWAS (p <4.95 × 10−6) where the risk variant also associated with earlier age of diagnosis. Given the role of the rs738409 in NAFLD diagnosis age, our results suggest that stratifying risk within populations known to have an enhanced risk of liver disease, such as Hispanic carriers of the rs738409 variant, would be effective in earlier identification of those who would benefit most from early NAFLD prevention and treatment strategies. Despite clear associations between the PNPLA3 rs738409 variant and elevated risk of progression from non-alcoholic fatty liver disease (NAFLD) to more severe forms of liver disease, it remains unknown if PNPLA3 rs738409 plays a role in the age of NAFLD onset. Herein, we found that this risk variant is associated with an earlier age of NAFLD and other liver disease diagnoses; an observation most pronounced in Hispanic Americans. We conclude that PNPLA3 rs738409 could be used to better understand liver disease risk within vulnerable populations and identify patients that may benefit from early prevention strategies. • Natural language processing increased NAFLD detection over ICD codes by 2.5 times. • rs738409 "GG" carriers were diagnosed with NAFLD 3 years earlier than non-carriers. • PNPLA3 rs738409 effects were most pronounced in Hispanics. • PheWAS showed rs738409 was associated with other NAFLD-related liver diseases. • rs738409 was associated with earlier diagnosis for PheWAS-identified diseases. [ABSTRACT FROM AUTHOR]

The calcium sensing receptor (CaSR) in the distal nephron decreases the propensity for calcium stones. Here we investigate if the apical CaSR in the proximal tubule also prevents stone formation acting via regulation of apical dicarboxylate and citrate transport. Urinary citrate, partially reabsorbed as a dicarboxylate in the proximal tubule lumen, inhibits stone formation by complexing calcium. We previously demonstrated a novel apical calcium-sensitive dicarboxylate transport system in OK proximal tubule cells. This calcium-sensitive process has the potential to modulate the amount of citrate available to complex increased urinary calcium. Using isotope labeled succinate uptake in OK cells along with various pharmacologic tools we examined whether the CaSR alters apical dicarboxylate transport and through which signal transduction pathways this occurs. Our results indicate that in the proximal tubule CaSR adjusts apical dicarboxylate transport, and does so via a CaSR → Gq → PKC signaling pathway. Thus, the CaSR may decrease the propensity for stone formation via actions in both proximal and distal nephron segments. [ABSTRACT FROM AUTHOR]

Objective: Excess fructose consumption is hypothesized to be associated with risk for metabolic disease. Actual fructose consumption levels are difficult to estimate because of the unlabeled quantity of fructose in beverages. The aims of this study were threefold: 1) re-examine the fructose content in previously tested beverages using two additional assay methods capable of detecting other sugars, especially maltose, 2) compare data across all methods to determine the actual free fructose-to-glucose ratio in beverages made either with or without high-fructose corn syrup (HFCS), and 3) expand the analysis to determine fructose content in commonly consumed juice products. Methods: Sugar-sweetened beverages (SSBs) and fruit juice drinks that were either made with or without HFCS were analyzed in separate, independent laboratories via three different methods to determine sugar profiles. Results: For SSBs, the three independent laboratory methods showed consistent and reproducible results. In SSBs made with HFCS, fructose constituted 60.6% ± 2.7% of sugar content. In juices sweetened with HFCS, fructose accounted for 52.1% ± 5.9% of sugar content, although in some juices made from 100% fruit, fructose concentration reached 65.35 g/L accounting for 67% of sugars. Conclusion: Our results provide evidence of higher than expected amounts of free fructose in some beverages. Popular beverages made with HFCS have a fructose-to-glucose ratio of approximately 60:40, and thus contain 50% more fructose than glucose. Some pure fruit juices have twice as much fructose as glucose. These findings suggest that beverages made with HFCS and some juices have a sugar profile very different than sucrose, in which amounts of fructose and glucose are equivalent. Current dietary analyses may underestimate actual fructose consumption. [ABSTRACT FROM AUTHOR]

Background: Melanocortin 4 receptor (MC4R) deficiency, caused by mutations in MC4R, is the most common cause of monogenic forms of obesity. However, these mutations have often been identified in small-scale, case-focused studies. Here, we assess the penetrance of previously reported MC4R mutations at a population level. Furthermore, we examine why some carriers of pathogenic mutations remain of normal weight, to gain insight into the mechanisms that control body weight.Methods and Findings: We identified 59 known obesity-increasing mutations in MC4R from the Human Gene Mutation Database (HGMD) and Clinvar. We assessed their penetrance and effect on obesity (body mass index [BMI] ≥ 30 kg/m2) in >450,000 individuals (age 40-69 years) of the UK Biobank, a population-based cohort study. Of these 59 mutations, only 11 had moderate-to-high penetrance and increased the odds of obesity by more than 2-fold. We subsequently focused on these 11 mutations and examined differences between carriers of normal weight and carriers with obesity. Twenty-eight of the 182 carriers of these 11 mutations were of normal weight. Body composition of carriers of normal weight was similar to noncarriers of normal weight, whereas among individuals with obesity, carriers had a somewhat higher BMI than noncarriers (1.44 ± 0.07 standard deviation scores [SDSs] ± standard error [SE] versus 1.29 ± 0.001, P = 0.03), because of greater lean mass (1.44 ± 0.09 versus 1.15 ± 0.002, P = 0.002). Carriers of normal weight more often reported that, already at age 10 years, their body size was below average or average (72%) compared with carriers with obesity (48%) (P = 0.01). To assess the polygenic contribution to body weight in carriers of normal weight and carriers with obesity, we calculated a genome-wide polygenic risk score for BMI (PRSBMI). The PRSBMI of carriers of normal weight (PRSBMI = -0.64 ± 0.18) was significantly lower than of carriers with obesity (0.40 ± 0.11; P = 1.7 × 10-6), and tended to be lower than that of noncarriers of normal weight (-0.29 ± 0.003; P = 0.05). Among carriers, those with a low PRSBMI (bottom quartile) have an approximately 5-kg/m2 lower BMI (approximately 14 kg of body weight for a 1.7-m-tall person) than those with a high PRS (top quartile). Because the UK Biobank population is healthier than the general population in the United Kingdom, penetrance may have been somewhat underestimated.Conclusions: We showed that large-scale data are needed to validate the impact of mutations observed in small-scale and case-focused studies. Furthermore, we observed that despite the key role of MC4R in obesity, the effects of pathogenic MC4R mutations may be countered, at least in part, by a low polygenic risk potentially representing other innate mechanisms implicated in body weight regulation. [ABSTRACT FROM AUTHOR]

Investigating genetic architecture of complex traits in ancestrally diverse populations is imperative to understand the etiology of disease. However, the current paucity of genetic research in people of African and Latin American ancestry, Hispanic and indigenous peoples in the United States is likely to exacerbate existing health disparities for many common diseases. The Population Architecture using Genomics and Epidemiology, Phase II (PAGE II), Study was initiated in 2013 by the National Human Genome Research Institute to expand our understanding of complex trait loci in ethnically diverse and well characterized study populations. To meet this goal, the Multi-Ethnic Genotyping Array (MEGA) was designed to substantially improve fine-mapping and functional discovery by increasing variant coverage across multiple ethnicities at known loci for metabolic, cardiovascular, renal, inflammatory, anthropometric, and a variety of lifestyle traits. Studying the frequency distribution of clinically relevant mutations, putative risk alleles, and known functional variants across multiple populations will provide important insight into the genetic architecture of complex diseases and facilitate the discovery of novel, sometimes population-specific, disease associations. DNA samples from 51,650 self-identified African ancestry (17,328), Hispanic/Latino (22,379), Asian/Pacific Islander (8,640), and American Indian (653) and an additional 2,650 participants of either South Asian or European ancestry, and other reference panels have been genotyped on MEGA by PAGE II. MEGA was designed as a new resource for studying ancestrally diverse populations. Here, we describe the methodology for selecting trait-specific content for use in multi-ethnic populations and how enriching MEGA for this content may contribute to deeper biological understanding of the genetic etiology of complex disease. [ABSTRACT FROM AUTHOR]

Introduction: Apolipoprotein C-III (apoC-III) regulates triglyceride (TG) metabolism. In plasma, apoC-III exists in non-sialylated (apoC-III0a without glycosylation and apoC-III0b with glycosylation), monosialylated (apoC-III1) or disialylated (apoC-III2) proteoforms. Our aim was to clarify the relationship between apoC-III sialylation proteoforms with fasting plasma TG concentrations. Methods: In 204 non-diabetic adolescent participants, the relative abundance of apoC-III plasma proteoforms was measured using mass spectrometric immunoassay. Results: Compared with the healthy weight subgroup (n = 16), the ratios of apoC-III0a, apoC-III0b, and apoC-III1 to apoC-III2 were significantly greater in overweight (n = 33) and obese participants (n = 155). These ratios were positively correlated with BMI z-scores and negatively correlated with measures of insulin sensitivity (Si). The relationship of apoC-III1 / apoC-III2 with Si persisted after adjusting for BMI (p = 0.02). Fasting TG was correlated with the ratio of apoC-III0a / apoC-III2 (r = 0.47, p<0.001), apoC-III0b / apoC-III2 (r = 0.41, p<0.001), apoC-III1 / apoC-III2 (r = 0.43, p<0.001). By examining apoC-III concentrations, the association of apoC-III proteoforms with TG was driven by apoC-III0a (r = 0.57, p<0.001), apoC-III0b (r = 0.56. p<0.001) and apoC-III1 (r = 0.67, p<0.001), but not apoC-III2 (r = 0.006, p = 0.9) concentrations, indicating that apoC-III relationship with plasma TG differed in apoC-III2 compared with the other proteoforms. Conclusion: We conclude that apoC-III0a, apoC-III0b, and apoC-III1, but not apoC- III2 appear to be under metabolic control and associate with fasting plasma TG. Measurement of apoC-III proteoforms can offer insights into the biology of TG metabolism in obesity. [ABSTRACT FROM AUTHOR]

Obesogens are compounds that disrupt the function and development of adipose tissue or the normal metabolism of lipids, leading to an increased risk of obesity and associated diseases. Evidence for the adverse effects of industrial and agricultural obesogens, such as tributyltin, bisphenol A and other organic pollutants is well-established. Current evidence suggests that high maternal consumption of fat promotes obesity and increased metabolic risk in offspring, but less is known about the effects of other potential nutrient obesogens. Widespread increase in dietary fructose consumption over the past 30 years is associated with chronic metabolic and endocrine disorders and alterations in feeding behaviour that promote obesity. In this Perspectives, we examine the evidence linking high intakes of fructose with altered metabolism and early obesity. We review the evidence suggesting that high fructose exposure during critical periods of development of the fetus, neonate and infant can act as an obesogen by affecting lifelong neuroendocrine function, appetite control, feeding behaviour, adipogenesis, fat distribution and metabolic systems. These changes ultimately favour the long-term development of obesity and associated metabolic risk. [ABSTRACT FROM AUTHOR]