Total body water and sicca symptoms in primary Sjögren's syndrome.

OBJECTIVES: To evaluated the total body water (TBW) among patients with primary Sjögren's syndrome (pSS) and assess its correlation with the severity of oral and ocular sicca symptoms, and some objective sicca variables. METHODS: We included 85 patients and 85 controls matched by sex, age, and body mass index (BMI). We assessed the Schirmer-I test and the non-stimulated whole salivary flow (NSWSF). We evaluated ocular and oral symptoms during the past 15 days using a 0-10 visual analogue scale (VAS) (highest score=worst symptoms). We obtained the TBW by bioelectric impedance analysis. RESULTS: 80% were women (mean age 54.8 years and mean disease duration 11.5 years). TBW was similar in pSS and controls (46.8±4.6 vs. 46.9±4.5, p=0.88). TBW correlated with age (ρ=-0.25, p=0.02), disease duration (ρ=-0.30, p=0.005), BMI (ρ=-0.78, p=0.001) and ocular VAS scale (ρ=-0.28, p=0.01); but not with NSWSF, Schirmer test or oral VAS scale. When comparing patients in the lowest TBW percentile (≤25%) with the remaining patients, the former group was older, had longer disease duration, higher BMI, lower frequency of anti-Ro/SSA and antinuclear antibodies, and higher ocular VAS scores. In the multivariate analysis, the ocular VAS score (OR 1.88, 95% CI 1.08-3.2, p=0.02) and the BMI 1.92 (OR 1.4, 95% CI 1.4-2.66, p=0.0001) remained associated with a lower TBW percentage. CONCLUSIONS: Patients with pSS had similar TBW percentages to control subjects. However, lower TBW percentages in the pSS were associated with higher BMI and also with the most severe ocular symptoms.

Identification of glucose and insulin patterns during A 5-H glucose tolerance test and association with cardiometabolic risk factors.

Background: Insulin resistance is key in the pathogenesis of the metabolic syndrome and cardiovascular disease. Objective: We aimed to identify glucose and insulin patterns after a 5-h oral glucose tolerance test (OGTT) in individuals without diabetes and to explore cardiometabolic risk factors, beta-cell function, and insulin sensitivity in each pattern. Methods: We analyzed the 5-h OGTT in a tertiary healthcare center. We identified classes using latent class trajectory analysis and evaluated their association with cardiometabolic risk factors, beta-cell function, and insulin sensitivity surrogates by multinomial logistic regression analysis. Results: We included 1088 5-h OGTT performed between 2013 and 2020 and identified four classes. Class one was associated with normal insulin sensitivity and secretion. Class two showed hyperglycemia, dysinsulinism, and a high-risk cardiometabolic profile (obesity, hypertriglyceridemia, and low high-density lipoprotein [HDL] cholesterol). Class three included older individuals, a higher proportion of males, and a greater prevalence of hypertension, hyperglycemia, hyperinsulinemia, and postprandial hypoglycemia. Finally, class four showed hyperglycemia, dysinsulinism, and hyperinsulinemia; this class had the worst cardiometabolic profile (a high proportion of males, greater age, hypertension, obesity, hypertriglyceridemia, and low HDL cholesterol, p < 0.001 vs. other classes). Conclusions: The latent class analysis approach allows the identification of groups with an adverse cardiometabolic risk factor, and who might benefit from frequent follow-ups and timely multidisciplinary interventions.

Natural course of metabolically healthy phenotype and risk of developing Cardiometabolic diseases: a three years follow-up study.

BACKGROUND: Whether the metabolically healthy obese (MHO) phenotype is a single, stable or a transitional, fluctuating state is currently unknown. The Mexican-Mestizo population has a genetic predisposition for the development of type 2 diabetes (T2D) and other cardiometabolic complications. Little is known about the natural history of metabolic health in this population. The aim of this study was to analyze the transitions over time among individuals with different degrees of metabolic health and body mass index, and evaluate the incidence of cardiometabolic outcomes according to phenotype. METHODS: The study population consisted of a metabolic syndrome cohort with at least 3 years of follow up. Participants were apparently-healthy urban Mexican adults ≥20 years with a body mass index (BMI) ≥20 kg/m2. Metabolically healthy phenotype was defined using the criteria of the National Cholesterol Education Program (NCEP) Adult Treatment Panel III (ATP III) metabolic syndrome criteria and the subjects were stratified into 4 groups according to their BMI and metabolic health. For cardiometabolic outcomes we estimated the incidence of cardiometabolic outcomes and standardized them per 1, 000 person-years of follow-up. Finally, to evaluate the risk for transition and development of cardiometabolic outcomes, we fitted Cox Proportional Hazard regression models. RESULTS: Amongst the 5541 subjects, 54.2% were classified as metabolically healthy and 45.8% as unhealthy. The MHO prevalence was 39.3%. Up to a third of the population changed from their initial category to another and the higher transition rate was observed in MHO (42.9%). We also found several novel factors associated to transition to metabolically unhealthy phenotype; socioeconomic status, number of pregnancies, a high carbohydrate intake, history of obesity and consumption of sweetened beverages. Similarly, visceral adipose tissue (VAT) was a main predictor of transition; loss of VAT ≥5% was associated with reversion from metabolically unhealthy to metabolically healthy phenotype (hazard ratio (HR) 1.545, 95%CI 1.266-1.886). Finally, we observed higher incidence rates and risk of incident T2D and hypertension in the metabolically unhealthy obesity (MUHO) and metabolically unhealthy lean (MUHL) phenotypes compared to MHO. CONCLUSIONS: Metabolic health is a dynamic and continuous process, at high risk of transition to metabolically unhealthy phenotypes over time. It is imperative to establish effective processes in primary care to prevent such transitions.

Comparative assessment of LDL-C and VLDL-C estimation in familial combined hyperlipidemia using Sampson's, Martin's and Friedewald's equations.

BACKGROUND: Sampson et al. developed a novel method to estimate very low-density lipoprotein cholesterol (VLDL-C) and low-density lipoprotein cholesterol (LDL-C) in the setting of hypertriglyceridemia. Familial Combined Hyperlipidemia (FCHL) is a common primary dyslipidemia in which lipoprotein composition interferes with LDL-C estimation. This study aimed to evaluate performance of LDL-C using this new method (LDL-S) compared with LDL-C estimated by Friedewald's and Martin eq. (LDL-F, LDL-M) in FCHL. METHODS: Data were collected from 340 subjects with confirmed FCHL. Concordance for VLDL-C measured by ultracentrifugation and LDL-C estimated using these measures compared to Sampson's, Martin's and Friedewald's equations was performed using correlation coefficients, root mean squared error (RMSE) and bias. Also, concordance of misclassified metrics according to LDL-C (< 70 and < 100 mg/dL) and Apo B (< 80 and < 65 mg/dL) thresholds were assessed. RESULTS: Sampson's equation was more accurate (RMSE 11.21 mg/dL; R2 = 0.88) compared to Martin's (RMSE 13.15 mg/dL; R2 = 0.875) and the Friedewald's equation (RMSE 13.7 mg/dL; R2 = 0.869). When assessing performance according to LDL-C, Sampson's had highest correlation and lowest RMSE compared to other equations (RMSE 19.99 mg/dL; R2 = 0.840). Comparing performance strength across triglyceride levels, Sampson's showed consistently improved correlations compared to Martin's and Friedewald's formulas for increasing triglycerides and for the FCHL phenotype of mixed dyslipidemia. Sampson's also had improved concordance with treatment goals. CONCLUSIONS: In FCHL, VLDL-C and LDL-C estimation using Sampson's formula showed higher concordance with lipid targets assessed using VLDL-C obtained by ultracentrifugation compared with Friedewald's and Martin's equations. Implementation of Sampson's formula could improve treatment monitoring in FCHL.

Familial hypertriglyceridemia: an entity with distinguishable features from other causes of hypertriglyceridemia.

BACKGROUND: Familial hypertriglyceridemia (FHTG) is a partially characterized primary dyslipidemia which is frequently confused with other forms hypertriglyceridemia. The aim of this work is to search for specific features that can help physicians recognize this disease. METHODS: This study included 84 FHTG cases, 728 subjects with common mild-to-moderate hypertriglyceridemia (CHTG) and 609 normotriglyceridemic controls. All subjects underwent genetic, clinical and biochemical assessments. A set of 53 single nucleotide polymorphisms (SNPs) previously associated with triglycerides levels, as well as 37 rare variants within the five main genes associated with hypertriglyceridemia (i.e. LPL, APOC2, APOA5, LMF1 and GPIHBP1) were analyzed. A panel of endocrine regulatory proteins associated with triglycerides homeostasis were compared between the FHTG and CHTG groups. RESULTS: Apolipoprotein B, fibroblast growth factor 21(FGF-21), angiopoietin-like proteins 3 (ANGPTL3) and apolipoprotein A-II concentrations, were independent components of a model to detect FHTG compared with CHTG (AUC 0.948, 95%CI 0.901-0.970, 98.5% sensitivity, 92.2% specificity, P < 0.001). The polygenic set of SNPs, accounted for 1.78% of the variance in triglyceride levels in FHTG and 6.73% in CHTG. CONCLUSIONS: The clinical and genetic differences observed between FHTG and CHTG supports the notion that FHTG is a unique entity, distinguishable from other causes of hypertriglyceridemia by the higher concentrations of insulin, FGF-21, ANGPTL3, apo A-II and lower levels of apo B. We propose the inclusion of these parameters as useful markers for differentiating FHTG from other causes of hypertriglyceridemia.

Association between insulin resistance and arterial stiffness in Mexican patients without type 2 diabetes.

BACKGROUND: Central aortic arterial stiffness (CAAS) is an independent cardiovascular risk factor. Insulin resistance (IR) contributes to CAAS-associated risk. OBJECTIVE: To evaluate the association between IR and CAAS in a Mexican population without diabetes. METHODS: IR was estimated with Homeostatic Model Assessment 2-Insulin Resistance (HOMA2-IR) and other surrogate markers (Metabolic score for IR [METS-IR], Quantitative Insulin Sensitivity Check Index [QUICKI], triglycerides/glucose index [TyG], TyG*body mass index [TyG*BMI] and triglycerides/high-density lipoprotein cholesterol ratio [TG/HDL-C]). CAAS was evaluated using carotid-femoral pulse wave velocity analysis (PWVcf) and the standardized augmentation index (AI-75). Bivariate correlations were made between surrogate markers and PWVcf. Increased CAAS was defined as PWVcf above the 90th percentile. Thresholds and area under the curve (AUC) were obtained for each surrogate marker in order to evaluate their performance in estimating increased CAAS. RESULTS: Three hundred and fifty-eight patients were included. A correlation was found between HOMA2-IR and PWVcf; this correlation was replicated with other surrogate markers. METS-IR and TyG*BMI had the highest degree of correlation with PWVcf. When adjustments were made for covariates, the correlations with TyG*BMI, METS-IR, HOMA2-IR and QUICKI maintained significance. HOMA2-IR showed the strongest correlation with AI-75. METS-IR and TyG showed the best AUC. Patients with prediabetes had the highest PWVcf. CONCLUSIONS: The relationship between IR and CAAS is present before the onset of diabetes; this association may entail higher cardiovascular risk.

ANTECEDENTES: La rigidez arterial central aórtica (RACA) es un factor de riesgo cardiovascular independiente. La resistencia a la insulina (RI) contribuye al riesgo asociado a RACA. OBJETIVO: Evaluar la asociación entre RI y RACA en una población mexicana sin diabetes. MÉTODOS: La RI se estimó con HOMA2-IR y (Homeostatic Model Assessment 2-Insulin Resistance) otros subrogados (METS-IR [Metabolic score for IR], QUICKI [Quantitative Insulin Sensitivity Check Index], TyG [ratio triglicéridos/glucosa], TyG*IMC [TyG*índice de masa corporal] y TG/HDL [ratio TG/lipoproteínas de alta densidad]). Se evaluó la RACA mediante el análisis de velocidad de onda del pulso carotídeo-femoral (VOPcf) y el índice de aumentación estandarizado (AI-75). Se realizaron correlaciones bivariante entre los subrogados y la VOPcf. RACA aumentada se definió como VOPcf arriba del percentil 90. Se obtuvieron puntos de corte y área bajo la curva (ABC) para cada subrogado para estimar RACA aumentada. RESULTADOS: Se incluyó 358 pacientes. Se encontró una correlación entre HOMA2-IR y VOPcf; esta correlación se replicó con los subrogados. METS-IR y TyG*IMC tuvieron el mayor grado de correlación con VOPcf. Al ajustar, las correlaciones con TyG*IMC, METS-IR, HOMA2-IR y QUICKI mantuvieron significancia. La correlación con AI-75 fue mayor para HOMA2-IR. METS-IR y TyG mostraron la mejor ABC. Los pacientes con prediabetes tuvieron mayor VOPcf. CONCLUSIONES: La relación entre la RI y la RACA está presente desde etapas no diabéticas; esta asociación puede conllevar mayor riesgo cardiovascular.

Omega-3 and omega-6 fatty acids in primary Sjögren's syndrome: clinical meaning and association with inflammation.

OBJECTIVES: Lipid mediators derived from polyunsaturated fatty acids (FA), have been related to inflammation and immune response regulation. Herein we evaluated the intake and serum levels of ω-3 and ω-6 FA among patients with primary Sjögren's syndrome (pSS), and correlated with ocular/oral sicca symptoms, disease activity and a panel of chemokines/cytokines. METHODS: We included 108 patients and 100 controls. Dietary information was obtained from a food questionnaire of one-day reminder and processed using a nutritional software. Among the SS group, we measured serum ω-3 (α-linolenic acid [α-LN], eicosapentaenoic acid [EPA], docosahexaenoic acid [DHA]) and ω-6 (linoleic acid [LA], arachidonic acid [AA]) by gas chromatography flame ionization. We scored the ESSDAI, ESPRI, Schirmer-I test and NSWSF. In a subsample, we assessed the OSDI, ophthalmologic staining scores and measured CXCL8, CXCL10, CCL2, IL-22 and IL-21 in saliva, and CXCL8, CXCL10, CCL2 and CXCL9 in tears by Luminometry. RESULTS: ω-3 and ω-6 intake was lower in SS patients than controls, and did not correlate with serum levels. We found a negative correlation between α-LN and the OSDI and ESSDAI, as well as DHA and ESSDAI. In tears, AA positively correlated with CXCL9, whereas in saliva, α-LN, DHA and the ω3 sum negatively correlated with CCL2. We observed a negative correlation between the ω6 sum and IL-21. CONCLUSIONS: pSS patients had deficient omega intake. Lower ocular symptoms, ESSDAI scores and salivary CCL2 correlated with higher ω-3 levels, possible suggesting a role in chronic inflammation. Further studies are warranted to deepen in the knowledge of this association.

Development and validation of a predictive model for incident type 2 diabetes in middle-aged Mexican adults: the metabolic syndrome cohort.

BACKGROUND: Type 2 diabetes mellitus (T2D) is a leading cause of morbidity and mortality in Mexico. Here, we aimed to report incidence rates (IR) of type 2 diabetes in middle-aged apparently-healthy Mexican adults, identify risk factors associated to ID and develop a predictive model for ID in a high-risk population. METHODS: Prospective 3-year observational cohort, comprised of apparently-healthy adults from urban settings of central Mexico in whom demographic, anthropometric and biochemical data was collected. We evaluated risk factors for ID using Cox proportional hazard regression and developed predictive models for ID. RESULTS: We included 7636 participants of whom 6144 completed follow-up. We observed 331 ID cases (IR: 21.9 per 1000 person-years, 95%CI 21.37-22.47). Risk factors for ID included family history of diabetes, age, abdominal obesity, waist-height ratio, impaired fasting glucose (IFG), HOMA2-IR and metabolic syndrome. Early-onset ID was also high (IR 14.77 per 1000 person-years, 95%CI 14.21-15.35), and risk factors included HOMA-IR and IFG. Our ID predictive model included age, hypertriglyceridemia, IFG, hypertension and abdominal obesity as predictors (Dxy = 0.487, c-statistic = 0.741) and had higher predictive accuracy compared to FINDRISC and Cambridge risk scores. CONCLUSIONS: ID in apparently healthy middle-aged Mexican adults is currently at an alarming rate. The constructed models can be implemented to predict diabetes risk and represent the largest prospective effort for the study metabolic diseases in Latin-American population.

Identification of a threshold to discriminate fasting hypertriglyceridemia with postprandial values.

BACKGROUND: Postprandial lipemia is an important cardiovascular risk factor. The assessment of postprandial lipid metabolism is a newly trend that several consortiums and countries have adopted. The aim of the study is to determine a postprandial triglyceride concentration cut-off point that accurately discriminate individuals with fasting normal triglyceride concentrations from those with fasting hypertriglyceridemia. METHODS: Cross sectional population-based study. A total of 212 subjects underwent an eight hours' oral fat tolerance test. Samples were taken fasting, three, four, five, six and eight hours after the meal. The area under the receiver operating characteristic curve (c-statistic) was computed using postprandial triglycerides concentrations as independent predictor, and fasting hypertriglyceridemia as dependent variable. RESULTS: The best threshold of postprandial lipemia to discriminate fasting hypertriglyceridemia was 280 mg/dL at any hour area under the curve 0.816 (95% confidence interval 0.753-0.866), bootstrap-corrected c-statistic = 0.733 (95% confidence interval 0.68-0.86). The same value was compared with apolipoprotein B concentrations (>90th percentile) having a good performance: area under the curve 0.687 95% confidence interval 0.624-0.751). Likewise, subjects with high postprandial lipemia have higher Globo risk scores. CONCLUSION: The 280 mg/dL cut-off point value of postprandial triglycerides concentration any time after a test meal discriminate subjects with fasting hypertriglyceridemia. This threshold has a good performance in a heterogeneous population and has a good concordance with cardiovascular risk surrogates.

FAMILIAL COMBINED HYPERLIPIDEMIA: CURRENT KNOWLEDGE, PERSPECTIVES, AND CONTROVERSIES.

Familial combined hyperlipidemia (FCHL) is the most prevalent primary dyslipidemia; however, it frequently remains undiagnosed and its precise definition is a subject of controversy. FCHL is characterized by fluctuations in serum lipid concentrations and may present as mixed hyperlipidemia, isolated hypercholesterolemia, hypertriglyceridemia, or as a normal serum lipid profile in combination with abnormally elevated levels of apolipoprotein B. FCHL is an oligogenic primary lipid disorder, which can occur due to the interaction of several contributing variants and mutations along with environmental triggers. Controversies surrounding the relevance of identifying FCHL as a cause of isolated hypertriglyceridemia and a differential diagnosis of familial hypertriglyceridemia are offset by the description of associations with USF1 and other genetic traits that are unique for FCHL and that are shared with other conditions with similar pathophysiological mechanisms. Patients with FCHL are at an increased risk of cardiovascular disease and mortality and have a high frequency of comorbidity with other metabolic conditions such as type 2 diabetes, non-alcoholic fatty liver disease, steatohepatitis, and the metabolic syndrome. Management usually requires lipid-lowering therapy directed toward reducing cholesterol and triglyceride concentrations along with cardiovascular risk protection. In recent years, the number of research studies on FCHL has been decreasing, mainly due to a lack of recognition of its impact on disease burden and comorbidity and the complexity in identifying probands for studies. This creates areas of opportunity to develop research for FCHL in epidemiology, genetics, pathophysiology, therapeutics, and cardiovascular risk management, which are discussed in depth in this review. (REV INVEST CLIN. 2018;70:224-36).

Molecular Characterization of the Lipid Genome-Wide Association Study Signal on Chromosome 18q11.2 Implicates HNF4A-Mediated Regulation of the TMEM241 Gene.

OBJECTIVE: We recently identified a locus on chromosome 18q11.2 for high serum triglycerides in Mexicans. We hypothesize that the lead genome-wide association study single-nucleotide polymorphism rs9949617, or its linkage disequilibrium proxies, regulates 1 of the 5 genes in the triglyceride-associated region. APPROACH AND RESULTS: We performed a linkage disequilibrium analysis and found 9 additional variants in linkage disequilibrium (r(2)>0.7) with the lead single-nucleotide polymorphism. To select the variants for functional analyses, we annotated the 10 variants using DNase I hypersensitive sites, transcription factor and chromatin states and identified rs17259126 as the lead candidate variant for functional in vitro validation. Using luciferase transcriptional reporter assay in liver HepG2 cells, we found that the G allele exhibits a significantly lower effect on transcription (P<0.05). The electrophoretic mobility shift and ChIPqPCR (chromatin immunoprecipitation coupled with quantitative polymerase chain reaction) assays confirmed that the minor G allele of rs17259126 disrupts an hepatocyte nuclear factor 4 α-binding site. To find the regional candidate gene, we performed a local expression quantitative trait locus analysis and found that rs17259126 and its linkage disequilibrium proxies alter expression of the regional transmembrane protein 241 (TMEM241) gene in 795 adipose RNAs from the Metabolic Syndrome In Men (METSIM) cohort (P=6.11×10(-07)-5.80×10(-04)). These results were replicated in expression profiles of TMEM241 from the Multiple Tissue Human Expression Resource (MuTHER; n=856). CONCLUSIONS: The Mexican genome-wide association study signal for high serum triglycerides on chromosome 18q11.2 harbors a regulatory single-nucleotide polymorphism, rs17259126, which disrupts normal hepatocyte nuclear factor 4 α binding and decreases the expression of the regional TMEM241 gene. Our data suggest that decreased transcript levels of TMEM241 contribute to increased triglyceride levels in Mexicans.

Genome-wide association study of colorectal cancer in Hispanics.

Genome-wide association studies (GWAS) have identified 58 susceptibility alleles across 37 regions associated with the risk of colorectal cancer (CRC) with P < 5×10(-8) Most studies have been conducted in non-Hispanic whites and East Asians; however, the generalizability of these findings and the potential for ethnic-specific risk variation in Hispanic and Latino (HL) individuals have been largely understudied. We describe the first GWAS of common genetic variation contributing to CRC risk in HL (1611 CRC cases and 4330 controls). We also examine known susceptibility alleles and implement imputation-based fine-mapping to identify potential ethnicity-specific association signals in known risk regions. We discovered 17 variants across 4 independent regions that merit further investigation due to suggestive CRC associations (P < 1×10(-6)) at 1p34.3 (rs7528276; Odds Ratio (OR) = 1.86 [95% confidence interval (CI): 1.47-2.36); P = 2.5×10(-7)], 2q23.3 (rs1367374; OR = 1.37 (95% CI: 1.21-1.55); P = 4.0×10(-7)), 14q24.2 (rs143046984; OR = 1.65 (95% CI: 1.36-2.01); P = 4.1×10(-7)) and 16q12.2 [rs142319636; OR = 1.69 (95% CI: 1.37-2.08); P=7.8×10(-7)]. Among the 57 previously published CRC susceptibility alleles with minor allele frequency ≥1%, 76.5% of SNPs had a consistent direction of effect and 19 (33.3%) were nominally statistically significant (P < 0.05). Further, rs185423955 and rs60892987 were identified as novel secondary susceptibility variants at 3q26.2 (P = 5.3×10(-5)) and 11q12.2 (P = 6.8×10(-5)), respectively. Our findings demonstrate the importance of fine mapping in HL. These results are informative for variant prioritization in functional studies and future risk prediction modeling in minority populations.

Factors associated with postprandial lipemia and apolipoprotein A-V levels in individuals with familial combined hyperlipidemia.

BACKGROUND: Alterations in postprandial metabolism have been described in familial combined hyperlipidemia (FCH); however, their underlying mechanisms are not well characterized. We aimed to identify factors related to the magnitude of postprandial lipemia and apolipoprotein (apo) A-V levels in subjects with FCH. METHODS: FCH cases (n = 99) were studied using a standardized meal test. Abdominal obesity was assessed using the waist to hip ratio (WHR). A linear regression model was performed to investigate the variables associated with the triglycerides incremental area under the curve (iAUC). Independent associations between metabolic variables and apo A-V iAUC were also investigated in a randomly selected subgroup (n = 44). The study sample was classified according to the presence of fasting hypertriglyceridemia (≥150 mg/dL) and abdominal obesity (WHR ≥0.92 in men and ≥0.85 in women) to explore differences in parameters. RESULTS: The fasting apo B-48 levels (r = 0.404), and the WHR (r = 0.359) were independent factors contributing to the triglycerides iAUC (r2 = 0.29, P < 0.001). The triglycerides iAUC was independently associated with the apo A-V iAUC (r2 = 0.54, P < 0.01). Patients with both hypertriglyceridemia and abdominal obesity showed the most robust triglycerides and apo A-V postprandial responses. CONCLUSIONS: In patients with FCH the fasting apo B-48 level is the main factor associated with postprandial lipemia. Abdominal obesity also contributes to the magnitude of the postprandial response.The triglycerides postprandial increment is the principal factor associated with the apo A-V postprandial response.

Genomic study in Mexicans identifies a new locus for triglycerides and refines European lipid loci.

BACKGROUND: The Mexican population and others with Amerindian heritage exhibit a substantial predisposition to dyslipidemias and coronary heart disease. Yet, these populations remain underinvestigated by genomic studies, and to date, no genome-wide association (GWA) studies have been reported for lipids in these rapidly expanding populations. METHODS AND FINDINGS: We performed a two-stage GWA study for hypertriglyceridemia and low high-density lipoprotein cholesterol (HDL-C) in Mexicans (n=4361), and identified a novel Mexican-specific genome-wide significant locus for serum triglycerides (TGs) near the Niemann-Pick type C1 protein gene (p=2.43×10(-08)). Furthermore, three European loci for TGs (APOA5, GCKR and LPL), and four loci for HDL-C (ABCA1, CETP, LIPC and LOC55908) reached genome-wide significance in Mexicans. We used cross-ethnic mapping to narrow three European TG GWA loci, APOA5, MLXIPL, and CILP2 that were wide and contained multiple candidate variants in the European scan. At the APOA5 locus, this reduced the most likely susceptibility variants to one, rs964184. Importantly, our functional analysis demonstrated a direct link between rs964184 and postprandial serum apoAV protein levels, supporting rs964184 as the causative variant underlying the European and Mexican GWA signal. Overall, 52 of the 100 reported associations from European lipid GWA meta-analysis generalised to Mexicans. However, in 82 of the 100 European GWA loci, a different variant other than the European lead/best-proxy variant had the strongest regional evidence of association in Mexicans. CONCLUSIONS: This first Mexican GWA study of lipids identified a novel GWA locus for high TG levels; used the interpopulation heterogeneity to significantly restrict three previously known European GWA signals, and surveyed whether the European lipid GWA SNPs extend to the Mexican population.

A systematic review of biobanks in Latin America: Strengths and limitations for biomedical research.

Biobanks are valuable tools for developing and applying scientific research and international cooperation through the collection of biological materials and their associated data. Systematic research following the Preferred Reporting Items for Systematic Review and Meta-Analysis guidelines was conducted in late 2022 in PubMed and Scopus, and generated 17 articles to be reviewed in depth and critically assessed using the Critical Appraisal Skills Programme Checklist due to the limited available data; 12 relevant health organizations and government websites outside of peer-reviewed journals were also included. Our research identified 44 biobanks in Latin America. In general, there is a lack of regulation and legislation guaranteeing the stored materials' quality and institutional collaboration. We believe a consensus needs to be reached regarding the terminology and definitions used for biobanks. The design for informed consent should also be agreed upon to ensure the privacy of the data shared among institutions. In conclusion, in Latin America, there is a clear need for government support in creating specific procedures for biobanks and providing further support for existing biobanks.

Performance of the enhanced Sampson-NIH equation for VLDL-C and LDL-C in a population with familial combined hyperlipidemia.

INTRODUCTION: Low-density cholesterol (LDL-C) has long been estimated by the Friedewald formula (F-LDL-C); however, this method underestimates LDL-C in patients with hypertriglyceridemia (HTG) or low LDL-C levels. The Martin (M-LDL-C) and Sampson (S-LDL-C) formulas partially resolve these limitations. Recently, Sampson et al. developed a new equation (eS-VLDL-C) that includes ApoB. This new equation could be particularly useful in FCHL, which is characterized by the predominance of triglyceride-rich VLDL and a discordance between LDL-C and ApoB. METHODS: Very low-density lipoproteins (VLDL-C) was measured in 336 patients with FCHL by sequential ultracentrifugation. LDL-C was estimated by subtracting VLDL-C, estimated by the different equations, from non-HDL cholesterol. Spearman correlations, R2, mean squared error (RMSE), and bias were used to compare the accuracy of the different equations. Concordance of the estimated LDL-C values with LDL-C thresholds and ApoB was also assessed by their kappa coefficients and ROC analysis. RESULTS: Overall population had a mean age of 47 years, and 61.5% were women. 19.5% had type 2 diabetes, hypertension was present in 20.8%, and only 12.2% were on statin treatment. Both S-LDL-C and eS-LDL-C performed similarly, and better than M-LDL-C and F-LDL-C. In Bland-Altman analysis, eS-LDL-C showed the lowest bias, better performance in HTG, and better concordance with LDL-C treatment goals compared to other formulas (e.g. ρ: 0.87, 95% CI 0.84-0.89). CONCLUSIONS: LDL-S and LDL-eS equations estimate the concentration of LDL-C with greater accuracy than other formulas. The LDL-eS has best performance in estimating LDL-C with lower RMSE than other formulas.

Evidence of how rs7575840 influences apolipoprotein B-containing lipid particles.

OBJECTIVE: Recent genome-wide association studies identified a variant rs7575840 in the apolipoprotein B (APOB) gene region as associated with low-density lipoprotein (LDL) cholesterol. However, the underlying functional mechanism of this variant, which resides 6.5 kb upstream of APOB, has remained unknown. Our objective was to investigate rs7575840 for association with refined apoB-containing lipid particles, for replication in a Mexican population, and for its underlying functional mechanism. METHODS AND RESULTS: Our data show that rs7575840 is associated with serum apoB levels (P=4.85×10(-10)) and apoB-containing lipid particles, very small very-low-density lipoprotein, intermediate lipoprotein, and LDL particles (P=2×10(-5) to 9×10(-7)) in the Finnish Metabolic Syndrome in Men study sample (n=7710). Fine mapping of the APOB region using 43 single-nucleotide polymorphisms replicated the association of rs7575840 with apoB in a Mexican study sample (n=2666, P=3.33×10(-5)). Furthermore, our transcript analyses of adipose RNA samples from 175 subjects in the Finnish Metabolic Syndrome in Men study indicate that rs7575840 alters expression of APOB (P=1.13×10(-10)) and a regional noncoding RNA (BU630349) (P=7.86×10(-6)) in adipose tissue. CONCLUSIONS: It has been difficult to convert genome-wide association study associations into mechanistic insights. Our data show that rs7575840 is associated with serum apoB levels and apoB-containing lipid particles, as well as influencing expression of APOB and a regional transcript BU630349 in adipose tissue. We thus provide evidence how a common genome-wide significant single-nucleotide polymorphism, rs7575840, may affect serum apoB, LDL cholesterol, and total cholesterol levels.

A systems genetics approach implicates USF1, FADS3, and other causal candidate genes for familial combined hyperlipidemia.

We hypothesized that a common SNP in the 3' untranslated region of the upstream transcription factor 1 (USF1), rs3737787, may affect lipid traits by influencing gene expression levels, and we investigated this possibility utilizing the Mexican population, which has a high predisposition to dyslipidemia. We first associated rs3737787 genotypes in Mexican Familial Combined Hyperlipidemia (FCHL) case/control fat biopsies, with global expression patterns. To identify sets of co-expressed genes co-regulated by similar factors such as transcription factors, genetic variants, or environmental effects, we utilized weighted gene co-expression network analysis (WGCNA). Through WGCNA in the Mexican FCHL fat biopsies we identified two significant Triglyceride (TG)-associated co-expression modules. One of these modules was also associated with FCHL, the other FCHL component traits, and rs3737787 genotypes. This USF1-regulated FCHL-associated (URFA) module was enriched for genes involved in lipid metabolic processes. Using systems genetics procedures we identified 18 causal candidate genes in the URFA module. The FCHL causal candidate gene fatty acid desaturase 3 (FADS3) was associated with TGs in a recent Caucasian genome-wide significant association study and we replicated this association in Mexican FCHL families. Based on a USF1-regulated FCHL-associated co-expression module and SNP rs3737787, we identify a set of causal candidate genes for FCHL-related traits. We then provide evidence from two independent datasets supporting FADS3 as a causal gene for FCHL and elevated TGs in Mexicans.

Autoimmune Thyroid Disease in Primary Sjögren's Syndrome: Real-life Screening Practice and Clinical Outcomes.

BACKGROUND: Notwithstanding the frequent coexistence of autoimmune thyroid disease (ATD) and primary Sjögren's Syndrome (SS), it is still unknown how often this association is studied along with its clinical impact. OBJECTIVE: This study aimed to describe real-world screening practices for ATD in patients with SS and evaluate clinical outcomes of patients with both diagnoses using validated activity and chronicity indexes. METHODS: It is a retrospective study of 223 patients with SS attending a tertiary referral center. Patients were under rheumatology surveillance and might have attended other clinics, including internal medicine and/or endocrinology. We registered glandular and extraglandular features, serology and scored the activity (ESSDAI) and the accrual damage (SSDDI) indexes. We also identified any thyroid function tests (TFT) performed, anti-thyroid antibodies, images, and histological thyroid examinations. A single endocrinologist reviewed all data. RESULTS: One hundred forty-nine patients had at least one set of TFT. Younger age was associated with a lack of screening (OR 0.98, 95 % CI 0.95-0.99, p=0.01). Sixty-nine patients had thyroid disease, with the most common diagnosis being ATD (n=24). Patients with ATD had a lower prevalence of Ro/SSA and anti-La/SSB antibodies but similar cumulative SS activity and damage scores. CONCLUSION: At least one-third of our patients were not screened for thyroid disease, with these patients being the youngest. Thyroid disorders were found in about 40 % of patients with SS, with ATD being the most common. Having SS/ATD did not confer more disease activity or damage accrual. These results highlight the importance of making treating physicians aware of screening for thyroid disease in this population.