MagicalRsq-X: A cross-cohort transferable genotype imputation quality metric.

Since genotype imputation was introduced, researchers have been relying on the estimated imputation quality from imputation software to perform post-imputation quality control (QC). However, this quality estimate (denoted as Rsq) performs less well for lower-frequency variants. We recently published MagicalRsq, a machine-learning-based imputation quality calibration, which leverages additional typed markers from the same cohort and outperforms Rsq as a QC metric. In this work, we extended the original MagicalRsq to allow cross-cohort model training and named the new model MagicalRsq-X. We removed the cohort-specific estimated minor allele frequency and included linkage disequilibrium scores and recombination rates as additional features. Leveraging whole-genome sequencing data from TOPMed, specifically participants in the BioMe, JHS, WHI, and MESA studies, we performed comprehensive cross-cohort evaluations for predominantly European and African ancestral individuals based on their inferred global ancestry with the 1000 Genomes and Human Genome Diversity Project data as reference. Our results suggest MagicalRsq-X outperforms Rsq in almost every setting, with 7.3%-14.4% improvement in squared Pearson correlation with true R2, corresponding to 85-218 K variant gains. We further developed a metric to quantify the genetic distances of a target cohort relative to a reference cohort and showed that such metric largely explained the performance of MagicalRsq-X models. Finally, we found MagicalRsq-X saved up to 53 known genome-wide significant variants in one of the largest blood cell trait GWASs that would be missed using the original Rsq for QC. In conclusion, MagicalRsq-X shows superiority for post-imputation QC and benefits genetic studies by distinguishing well and poorly imputed lower-frequency variants.

TOP-LD: A tool to explore linkage disequilibrium with TOPMed whole-genome sequence data.

Current publicly available tools that allow rapid exploration of linkage disequilibrium (LD) between markers (e.g., HaploReg and LDlink) are based on whole-genome sequence (WGS) data from 2,504 individuals in the 1000 Genomes Project. Here, we present TOP-LD, an online tool to explore LD inferred with high-coverage (∼30×) WGS data from 15,578 individuals in the NHLBI Trans-Omics for Precision Medicine (TOPMed) program. TOP-LD provides a significant upgrade compared to current LD tools, as the TOPMed WGS data provide a more comprehensive representation of genetic variation than the 1000 Genomes data, particularly for rare variants and in the specific populations that we analyzed. For example, TOP-LD encompasses LD information for 150.3, 62.2, and 36.7 million variants for European, African, and East Asian ancestral samples, respectively, offering 2.6- to 9.1-fold increase in variant coverage compared to HaploReg 4.0 or LDlink. In addition, TOP-LD includes tens of thousands of structural variants (SVs). We demonstrate the value of TOP-LD in fine-mapping at the GGT1 locus associated with gamma glutamyltransferase in the African ancestry participants in UK Biobank. Beyond fine-mapping, TOP-LD can facilitate a wide range of applications that are based on summary statistics and estimates of LD. TOP-LD is freely available online.

Whole genome sequence analysis of platelet traits in the NHLBI Trans-Omics for Precision Medicine (TOPMed) initiative.

Platelets play a key role in thrombosis and hemostasis. Platelet count (PLT) and mean platelet volume (MPV) are highly heritable quantitative traits, with hundreds of genetic signals previously identified, mostly in European ancestry populations. We here utilize whole genome sequencing (WGS) from NHLBI's Trans-Omics for Precision Medicine initiative (TOPMed) in a large multi-ethnic sample to further explore common and rare variation contributing to PLT (n = 61 200) and MPV (n = 23 485). We identified and replicated secondary signals at MPL (rs532784633) and PECAM1 (rs73345162), both more common in African ancestry populations. We also observed rare variation in Mendelian platelet-related disorder genes influencing variation in platelet traits in TOPMed cohorts (not enriched for blood disorders). For example, association of GP9 with lower PLT and higher MPV was partly driven by a pathogenic Bernard-Soulier syndrome variant (rs5030764, p.Asn61Ser), and the signals at TUBB1 and CD36 were partly driven by loss of function variants not annotated as pathogenic in ClinVar (rs199948010 and rs571975065). However, residual signal remained for these gene-based signals after adjusting for lead variants, suggesting that additional variants in Mendelian genes with impacts in general population cohorts remain to be identified. Gene-based signals were also identified at several genome-wide association study identified loci for genes not annotated for Mendelian platelet disorders (PTPRH, TET2, CHEK2), with somatic variation driving the result at TET2. These results highlight the value of WGS in populations of diverse genetic ancestry to identify novel regulatory and coding signals, even for well-studied traits like platelet traits.

Multiplexed imaging in live cells using pulsed interleaved excitation spectral FLIM.

Multiplexed fluorescence detection has become increasingly important in the fields of biosensing and bioimaging. Although a variety of excitation/detection optical designs and fluorescence unmixing schemes have been proposed to allow for multiplexed imaging, rapid and reliable differentiation and quantification of multiple fluorescent species at each imaging pixel is still challenging. Here we present a pulsed interleaved excitation spectral fluorescence lifetime microscopic (PIE-sFLIM) system that can simultaneously image six fluorescent tags in live cells in a single hyperspectral snapshot. Using an alternating pulsed laser excitation scheme at two different wavelengths and a synchronized 16-channel time-resolved spectral detector, our PIE-sFLIM system can effectively excite multiple fluorophores and collect their emission over a broad spectrum for analysis. Combining our system with the advanced live-cell labeling techniques and the lifetime/spectral phasor analysis, our PIE-sFLIM approach can well unmix the fluorescence of six fluorophores acquired in a single measurement, thus improving the imaging speed in live-specimen investigation.

Assessing the impact of extracellular matrix fiber orientation on breast cancer cellular metabolism.

The extracellular matrix (ECM) is a dynamic and complex microenvironment that modulates cell behavior and cell fate. Changes in ECM composition and architecture have been correlated with development, differentiation, and disease progression in various pathologies, including breast cancer [1]. Studies have shown that aligned fibers drive a pro-metastatic microenvironment, promoting the transformation of mammary epithelial cells into invasive ductal carcinoma via the epithelial-to-mesenchymal transition (EMT) [2]. The impact of ECM orientation on breast cancer metabolism, however, is largely unknown. Here, we employ two non-invasive imaging techniques, fluorescence-lifetime imaging microscopy (FLIM) and intensity-based multiphoton microscopy, to assess the metabolic states of cancer cells cultured on ECM-mimicking nanofibers in a random and aligned orientation. By tracking the changes in the intrinsic fluorescence of nicotinamide adenine dinucleotide and flavin adenine dinucleotide, as well as expression levels of metastatic markers, we reveal how ECM fiber orientation alters cancer metabolism and EMT progression. Our study indicates that aligned cellular microenvironments play a key role in promoting metastatic phenotypes of breast cancer as evidenced by a more glycolytic metabolic signature on nanofiber scaffolds of aligned orientation compared to scaffolds of random orientation. This finding is particularly relevant for subsets of breast cancer marked by high levels of collagen remodeling (e.g. pregnancy associated breast cancer), and may serve as a platform for predicting clinical outcomes within these subsets [3-6].

Advancing immunomodulatory functions in mesenchymal stem/stromal cells through targeting the GATA6-mediated pathway.

BACKGROUND AIMS: The immunomodulatory capacity of mesenchymal stem/stromal cells (MSCs) is a key feature that makes them particularly valuable for regenerative medicine. However, this potential is affected by the chronological aging of the donors and the cell expansion procedures in culture. We have demonstrated that GATA binding protein 6 (GATA6) plays a pivotal role in the aging of MSCs and inhibiting GATA6 rejuvenates the characteristics of MSCs. METHODS: In this study, we compared the immunomodulatory capabilities of young and old MSC models, using induced pluripotent stem cells-derived rejuvenated MSCs (rMSCs) and their parental MSCs (pMSCs), respectively, to identify a key mechanism involved in the differential regulation of these capabilities. Additionally, we explored the role of GATA6 in mediating the mechanism. RESULTS: Our results demonstrated that rMSCs exhibited downregulated aging-associated regulators, including p53, p21 and GATA6, and showed enhanced suppression of T cell proliferation compared to pMSCs. Through analyzing our previous RNA-seq data and employing target gene knockdown, we determined both suppressors of cytokine signaling 3 (SOCS3) and interleukin 6 were involved in GATA6-induced regulation, collectively affecting the expression of programmed death ligand 1 (PDL1) in both pMSCs and rMSCs. CONCLUSIONS: Our findings underline the significance of the GATA6/SOCS3/PDL1 pathway in regulating aging-associated changes in MSC immunomodulatory activity, providing valuable insights into the potential use of rMSCs in the treatment of immune diseases and regenerative medicine.

Monogenic and Polygenic Contributions to QTc Prolongation in the Population.

BACKGROUND: Rare sequence variation in genes underlying cardiac repolarization and common polygenic variation influence QT interval duration. However, current clinical genetic testing of individuals with unexplained QT prolongation is restricted to examination of monogenic rare variants. The recent emergence of large-scale biorepositories with sequence data enables examination of the joint contribution of rare and common variations to the QT interval in the population. METHODS: We performed a genome-wide association study of the QTc in 84 630 UK Biobank participants and created a polygenic risk score (PRS). Among 26 976 participants with whole-genome sequencing and ECG data in the TOPMed (Trans-Omics for Precision Medicine) program, we identified 160 carriers of putative pathogenic rare variants in 10 genes known to be associated with the QT interval. We examined QTc associations with the PRS and with rare variants in TOPMed. RESULTS: Fifty-four independent loci were identified by genome-wide association study in the UK Biobank. Twenty-one loci were novel, of which 12 were replicated in TOPMed. The PRS composed of 1 110 494 common variants was significantly associated with the QTc in TOPMed (ΔQTc/decile of PRS=1.4 ms [95% CI, 1.3 to 1.5]; P=1.1×10-196). Carriers of putative pathogenic rare variants had longer QTc than noncarriers (ΔQTc=10.9 ms [95% CI, 7.4 to 14.4]). Of individuals with QTc>480 ms, 23.7% carried either a monogenic rare variant or had a PRS in the top decile (3.4% monogenic, 21% top decile of PRS). CONCLUSIONS: QTc duration in the population is influenced by both rare variants in genes underlying cardiac repolarization and polygenic risk, with a sizeable contribution from polygenic risk. Comprehensive assessment of the genetic determinants of QTc prolongation includes incorporation of both polygenic and monogenic risk.

Digital Connectedness in the Jackson Heart Study: Cross-sectional Study.

BACKGROUND: Although new approaches for data collection, such as mobile technology and teleresearch, have demonstrated new opportunities for the conduct of more timely and less costly surveys in community-based studies, literature on the feasibility of conducing cardiovascular disease research using mobile health (mHealth) platforms among middle-aged and older African Americans has been limited. OBJECTIVE: The purpose of this study was to contribute to the knowledge regarding the penetrance of internet and mobile technologies, such as cellphones or smartphones in existing large cohort studies of cardiovascular disease. METHODS: A digital connectedness survey was conducted in the Jackson Heart Study (JHS), a Mississippi-based African American cohort study, as part of the annual follow-up calls with participants from July 2017 to February 2019. RESULTS: Of the 4024 participants contacted, 2564 (63.7%) completed the survey. Among survey respondents, 2262 (88.2%) reported use of internet or cellphone, and 1593 (62.1%) had a smartphone. Compared to nonusers (n=302), internet or cellphone users (n=2262) were younger (mean age 80.1, SD 8.0 vs 68.2, SD 11.3 years), more likely to be affluent (n=778, 40.1% vs n=39, 15.4%), and had greater than high school education (n=1636, 72.5% vs n=85, 28.1%). Internet or cellphone users were less likely to have cardiovascular disease history compared to nonusers (136/2262, 6.6% vs 41/302, 15.8%). The prevalence of current smoking and average BMI were similar between internet or cellphone users and nonusers. Among internet or cellphone users, 1316 (58.3%) reported use of email, 504 (22.3%) reported use of apps to track or manage health, and 1269 (56.1%) expressed interest in using JHS-developed apps. CONCLUSIONS: Our findings suggest that it is feasible to use mHealth technologies to collect survey data among African Americans already enrolled in a longitudinal study. Our findings also highlight the need for more efforts to reduce the age and education divide in access and use of internet and smartphones for tracking health and research in African American communities.

Experiences of Discrimination Are Associated With Worse Metabolic Syndrome Severity Among African Americans in the Jackson Heart Study.

BACKGROUND: Metabolic syndrome (MetS) is a risk factor for the development of cardiovascular disease and type 2 diabetes. Although the development of MetS is attributed to known lifestyle factors, perceived discrimination may also contribute to MetS development and severity. PURPOSE: We examined the associations of perceived discrimination with MetS severity among African American adults at baseline and 8-year follow-up. METHODS: Three thousand eight hundred and seventy participants (mean age 53.8 ± 13.0; 63.1% female) without diabetes and no missing MetS severity scores at baseline were included. Each self-reported measure of discrimination at baseline (everyday, lifetime, and burden of lifetime) was classified into tertiles (low, medium, high). After adjustment for demographics and MetS risk factors, associations of discrimination were examined with a sex- and race/ethnicity-specific MetS severity Z-score. We employed a mixed model approach that allowed for the assessment of an overall association between reported discrimination at baseline and MetS severity, and for the possible change over time. RESULTS: Sex and age differences were observed in experiences with discrimination, such that men reported higher levels of all aspects of discrimination relative to women. Everyday discrimination decreased with age, whereas lifetime discrimination increased with age (p < .05). Independent of lifestyle and demographic factors, everyday and lifetime discrimination were significantly associated with MetS severity (p = .003 and p = .017, respectively) and the associations remained constant over the 8 years (i.e., no interaction with time). CONCLUSIONS: Our results suggest that, in a large community-based sample of African Americans, discrimination is a salient psychosocial risk factor for severity of MetS.

Obesity and overall mortality: findings from the Jackson Heart Study.

BACKGROUND: Overall mortality has been reported to be lower among individuals classified as overweight/obese when compared with their normal weight counterparts ("obesity paradox") when obesity classification is based on the body mass index (BMI). One possible reason for this apparent paradox is that BMI is not a reliable measure of obesity-related risk as it does not differentiate fat mass from lean muscle mass or fat mass phenotypes. Waist circumference (WC), as a measure of central adiposity, may be a better indicator of obesity-related risk. We examined the association of overall mortality with BMI and with WC measures, including WC, waist-to-height ratio (WHtR) and waist-to-hip ratio (WHR). METHODS: Data from 3976 African American participants (551 deaths) in the Jackson Heart Study (JHS) were analyzed. Cox regression models were used to perform survival analysis. Obesity measures were analyzed as dichotomous (obese/non-obese) and continuous variables. Baseline covariates included age, sex and smoking status. RESULTS: Comparing obese to non-obese participants, adjusted hazard ratios (95% CI) for overall mortality were 1.14 (0.96, 1.35), 1.30 (1.07, 1.59), 1.02 (0.73, 1.41) and 1.45 (1.18, 1.79) when using BMI, WC, WHtR and WHR, respectively. For BMI, WC and WHtR, a J-shaped relationship was observed with overall mortality. For WHR, a monotonic increasing relationship was observed with overall mortality. CONCLUSIONS: In the JHS, we found that obesity as defined by WC and WHR was associated with an increased risk of overall and CVD mortality, while obesity defined by BMI was associated only with an increased risk of CVD mortality. WHR was the only obesity measure that showed a monotonic increasing relationship with overall and CVD mortality.

Joint modelling of longitudinal lipids and time to coronary heart disease in the Jackson Heart Study.

BACKGROUND: Multiple longitudinal responses together with time-to-event outcome are common in biomedical studies. There are several instances where the longitudinal responses are correlated with each other and at the same time each longitudinal response is associated with the survival outcome. The main purpose of this study is to present and explore a joint modeling approach for multiple correlated longitudinal responses and a survival outcome. The method will be illustrated using the Jackson Heart Study (JHS), which is one of the largest cardiovascular studies among African Americans. METHODS: Four longitudinal responses, i.e., total cholesterol (TC), high density lipoprotein (HDL) cholesterol, triglyceride (TG) and inflammation measured by high-sensitivity C-reactive protein (hsCRP); and time-to-coronary heart disease (CHD) were considered from the JHS. The repeated lipid and hsCRP measurements from a given subject overtime are likely correlated with each other and could influence the subject's risk for CHD. A joint modeling framework is considered. To deal with the high dimensionality due to the multiple longitudinal profiles, we use a pairwise bivariate model fitting approach that was developed in the context of multivariate Gaussian random effects models. The method is further explored through simulations. RESULTS: The proposed model performed well in terms of bias and relative efficiency. The JHS data analysis showed that lipid and hsCRP trajectories could exhibit interdependence in their joint evolution and have impact on CHD risk. CONCLUSIONS: We applied a unified and flexible joint modeling approach to analyze multiple correlated longitudinal responses and survival outcome. The method accounts for the correlation among the longitudinal responses as well as the association between each longitudinal response and the survival outcome at once. This helps to explore how the combination of multiple longitudinal trajectories could be related to the survival process.

Measuring DNA Hybridization Kinetics in Live Cells Using a Time-Resolved 3D Single-Molecule Tracking Method.

Single-molecule detection enables direct characterization of annealing/melting kinetics of nucleic acids without the need for synchronization of molecular states, but the current experiments are not carried out in a native cellular context. Here we describe an integrated 3D single-molecule tracking and lifetime measurement method that can follow individual DNA molecules diffusing inside a mammalian cell and observe multiple annealing and melting events on the same molecules. By comparing the hybridization kinetics of the same DNA strand in vitro, we found the association constants can be 13- to 163-fold higher in the molecular crowding cellular environment.

p53-/- synergizes with enhanced NrasG12D signaling to transform megakaryocyte-erythroid progenitors in acute myeloid leukemia.

Somatic mutations in TP53 and NRAS are associated with transformation of human chronic myeloid diseases to acute myeloid leukemia (AML). Here, we report that concurrent RAS pathway and TP53 mutations are identified in a subset of AML patients and confer an inferior overall survival. To further investigate the genetic interaction between p53 loss and endogenous NrasG12D/+ in AML, we generated conditional NrasG12D/+p53-/- mice. Consistent with the clinical data, recipient mice transplanted with NrasG12D/+p53-/- bone marrow cells rapidly develop a highly penetrant AML. We find that p53-/- cooperates with NrasG12D/+ to promote increased quiescence in megakaryocyte-erythroid progenitors (MEPs). NrasG12D/+p53-/- MEPs are transformed to self-renewing AML-initiating cells and are capable of inducing AML in serially transplanted recipients. RNA sequencing analysis revealed that transformed MEPs gain a partial hematopoietic stem cell signature and largely retain an MEP signature. Their distinct transcriptomes suggests a potential regulation by p53 loss. In addition, we show that during AML development, transformed MEPs acquire overexpression of oncogenic Nras, leading to hyperactivation of ERK1/2 signaling. Our results demonstrate that p53-/- synergizes with enhanced oncogenic Nras signaling to transform MEPs and drive AML development. This model may serve as a platform to test candidate therapeutics in this aggressive subset of AML.

Optimism and cardiovascular health among African Americans in the Jackson Heart Study.

Little research has examined associations of positive psychosocial factors with the American Heart Association Life's Simple 7™ (LS7) among African Americans. This study examined the associations between positive optimistic orientation and LS7 among African Americans. Using exam 1 data (2000-2004) from the Jackson Heart Study, we examined cross-sectional associations of optimism (in tertiles) with LS7 components [smoking, physical activity, diet, body mass index, blood pressure, cholesterol, glucose] and a composite LS7 score (classified as poor, intermediate, ideal) among 4734 African Americans free of cardiovascular disease. Multivariable prevalence regression was used to estimate prevalence ratios (PR, 95% confidence interval-CI) of intermediate and ideal (vs. poor) individual LS7 components and composite LS7 score by optimism levels, adjusting for demographics, socioeconomic status, and depressive symptoms. For LS7 components with low prevalence, we estimated odds ratios. A greater percentage of participants with high vs. low optimism were younger, female, high SES, and not depressed. After full covariate adjustment, the prevalence ratio of ideal (vs. poor) composite LS7 score was 1.24 for participants who reported high (vs. low) optimism (95% CI 1.09-1.42) at exam 1. Higher levels of optimism were also associated with greater prevalence of ideal (vs. poor) physical activity and smoking. Promoting positive optimistic orientation may be an important step toward increasing the likelihood of achieving optimal cardiovascular health among African Americans.

Self-reported snoring and incident cardiovascular disease events: results from the Jackson Heart Study.

PURPOSE: Evidence suggests that snoring is associated with increased risk for cardiovascular disease (CVD) events such as myocardial infarction and stroke. Limited data exists pertaining to this association among African Americans. We therefore examined the association between self-reported habitual snoring and incident CVD in the Jackson Heart Study (JHS), a population-based cohort study of African Americans. METHODS: Self-reported data on snoring and risk factors for CVD were collected at baseline (2000-2004). Participants were followed prospectively for the development of incident CVD. Habitual snoring was defined as present if the participants reported it as "often" or "almost always" or absent if reported as "sometimes," "never," or "seldom." A CVD event included stroke, myocardial infarction, coronary revascularization procedure, or fatal CHD event. Cox proportional hazards models assessed the independent association between self-reported habitual snoring and incident CVD event adjusting for multiple covariates, including age, sex, hypertension, body mass index, diabetes, hypercholesterolemia, and smoking status. RESULTS: The snorer group consisted of 787 participants (mean age 52.1 years) and the nonsnorer group consisted of 3708 participants (mean age 54.9 years). Frequency of incident CVD events in the snorer group was not significantly different from the nonsnorer group. The fully adjusted hazard ratio for a CVD event in the snorer group was 1.01 (95% confidence interval [0.69, 1.47], p value of 0.96). CONCLUSION: In conclusion, self-reported habitual snoring was not associated with incident CVD among this large African American cohort. Future studies providing objective data on snoring and sleep apnea may provide more information on the snoring-CVD association among African Americans. TRIAL REGISTRATION: Identification Number: NCT00005485.

Association of functional and structural social support with chronic kidney disease among African Americans: the Jackson Heart Study.

BACKGROUND: There is limited evidence on the relationship between social support and renal outcomes in African Americans. We sought to determine the association of social support with prevalent chronic kidney disease (CKD) and kidney function decline in an African American cohort. We also examined whether age modifies the association between social support and kidney function decline. METHODS: We identified Jackson Heart Study (JHS) participants with baseline (Exam in 2000-2004) functional and structural social support data via the Interpersonal Support Evaluation List (ISEL) and social network size questions, respectively. With ISEL as our primary exposure variable, we performed multivariable regression models to evaluate the association between social support and prevalent CKD [estimated glomerular filtration rate (eGFR) < 60 ml/min/1.73 m2 or urine albumin-creatinine ratio (ACR) ≥30 mg/g], eGFR decline, and rapid renal function decline (RRFD) (> 30% decrease in eGFR over approximately 10 years). All models were adjusted for baseline sociodemographics, diabetes, hypertension, smoking status, and body mass index; models for eGFR decline and RRFD were additionally adjusted for eGFR and ACR. In models for eGFR decline, we assessed for interaction between age and social support. For secondary analyses, we replaced ISEL with its individual domains (appraisal, belonging, self-esteem, and tangible) and social network size in separate models as exposure variables. RESULTS: Of 5301 JHS participants, 4015 (76%) completed the ISEL at baseline. 843 (21%) had low functional social support (ISEL score < 32). Participants with low (vs. higher) functional social support were more likely to have lower income (47% vs. 28%), be current or former tobacco users (39% vs. 30%), have diabetes (25% vs. 21%) or CKD (14% vs. 12%). After multivariable adjustment, neither ISEL or social network size were independently associated with prevalent CKD, eGFR decline, or RRFD. Of the ISEL domains, only higher self-esteem was associated with lower odds of prevalent CKD [OR 0.94 (95% CI 0.89-0.99)]. The associations between social support measures and eGFR decline were not modified by age. CONCLUSIONS: In this African-American cohort, social support was not associated with prevalent CKD or kidney function decline. Further inquiry of self-esteem's role in CKD self-management and renal outcomes is warranted.

Clinical Implications of Revised Pooled Cohort Equations for Estimating Atherosclerotic Cardiovascular Disease Risk.

Background: The 2013 pooled cohort equations (PCEs) are central in prevention guidelines for cardiovascular disease (CVD) but can misestimate CVD risk. Objective: To improve the clinical accuracy of CVD risk prediction by revising the 2013 PCEs using newer data and statistical methods. Design: Derivation and validation of risk equations. Setting: Population-based. Participants: 26 689 adults aged 40 to 79 years without prior CVD from 6 U.S. cohorts. Measurements: Nonfatal myocardial infarction, death from coronary heart disease, or fatal or nonfatal stroke. Results: The 2013 PCEs overestimated 10-year risk for atherosclerotic CVD by an average of 20% across risk groups. Misestimation of risk was particularly prominent among black adults, of whom 3.9 million (33% of eligible black persons) had extreme risk estimates (<70% or >250% those of white adults with otherwise-identical risk factor values). Updating these equations improved accuracy among all race and sex subgroups. Approximately 11.8 million U.S. adults previously labeled high-risk (10-year risk ≥7.5%) by the 2013 PCEs would be relabeled lower-risk by the updated equations. Limitations: Updating the 2013 PCEs with data from modern cohorts reduced the number of persons considered to be at high risk. Clinicians and patients should consider the potential benefits and harms of reducing the number of persons recommended aspirin, blood pressure, or statin therapy. Our findings also indicate that risk equations will generally become outdated over time and require routine updating. Conclusion: Revised PCEs can improve the accuracy of CVD risk estimates. Primary Funding Source: National Institutes of Health.

Representativeness of Medicare Participants in the Jackson Heart Study for African American Medicare Beneficiaries.

BACKGROUND: The Jackson Heart Study (JHS) assesses cardiovascular disease risk factors among African Americans in Jackson, Mississippi. Whether characteristics of JHS participants differ from those of a broader African American population are unknown. METHODS: In a retrospective observational analysis, we compared characteristics and outcomes of JHS participants 65 years old and older and enrolled in Medicare (n = 1,105) to regional (n = 57,489) and national (n = 95,494) cohorts of African American Medicare beneficiaries. We weighted the regional and national cohorts to match the age and sex distributions of the JHS-Medicare cohort for pairwise baseline comparisons. Outcomes of interest included mortality and Medicare costs. We used Cox proportional hazards models to test associations between cohorts and outcomes. RESULTS: The JHS-Medicare cohort was younger, included more women, and had fewer beneficiaries with dual Medicare-Medicaid eligibility, compared with regional and national Medicare cohorts. The cohort also had lower risks of stroke, lung disease, heart failure, diabetes, and renal disease. Mean Medicare costs were lower ($5,066 [SD = $11,932]) than in the regional ($7,419 [SD = $17,574]) and national ($8,013 [SD = $19,378]) cohorts. The regional and national cohorts had higher mortality (adjusted hazard ratios = 1.52; 95% confidence interval [CI] = 1.31, 1.76; and 1.49; 95% CI = 1.29, 1.73, respectively). Subgroup analysis for dual Medicare-Medicaid eligibility attenuated mortality differences. CONCLUSION: JHS-Medicare participants had fewer comorbid conditions, better survival, and lower Medicare costs compared with regional and national cohorts. Observed differences may reflect healthy volunteer bias and higher socioeconomic status.See video abstract at, http://links.lww.com/EDE/B235.

Mechanism governing a stem cell-generating cis-regulatory element.

The unremitting demand to replenish differentiated cells in tissues requires efficient mechanisms to generate and regulate stem and progenitor cells. Although master regulatory transcription factors, including GATA binding protein-2 (GATA-2), have crucial roles in these mechanisms, how such factors are controlled in developmentally dynamic systems is poorly understood. Previously, we described five dispersed Gata2 locus sequences, termed the -77, -3.9, -2.8, -1.8, and +9.5 GATA switch sites, which contain evolutionarily conserved GATA motifs occupied by GATA-2 and GATA-1 in hematopoietic precursors and erythroid cells, respectively. Despite common attributes of transcriptional enhancers, targeted deletions of the -2.8, -1.8, and +9.5 sites revealed distinct and unpredictable contributions to Gata2 expression and hematopoiesis. Herein, we describe the targeted deletion of the -3.9 site and mechanistically compare the -3.9 site with other GATA switch sites. The -3.9(-/-) mice were viable and exhibited normal Gata2 expression and steady-state hematopoiesis in the embryo and adult. We established a Gata2 repression/reactivation assay, which revealed unique +9.5 site activity to mediate GATA factor-dependent chromatin structural transitions. Loss-of-function analyses provided evidence for a mechanism in which a mediator of long-range transcriptional control [LIM domain binding 1 (LDB1)] and a chromatin remodeler [Brahma related gene 1 (BRG1)] synergize through the +9.5 site, conferring expression of GATA-2, which is known to promote the genesis and survival of hematopoietic stem cells.

Nras(G12D/+) promotes leukemogenesis by aberrantly regulating hematopoietic stem cell functions.

Oncogenic NRAS mutations are frequently identified in human myeloid leukemias. In mice, expression of endogenous oncogenic Nras (Nras(G12D/+)) in hematopoietic cells leads to expansion of myeloid progenitors, increased long-term reconstitution of bone marrow cells, and a chronic myeloproliferative neoplasm (MPN). However, acute expression of Nras(G12D/+) in a pure C57BL/6 background does not induce hyperactivated granulocyte macrophage colony-stimulating factor signaling or increased proliferation in myeloid progenitors. It is thus unclear how Nras(G12D/+) signaling promotes leukemogenesis. Here, we show that hematopoietic stem cells (HSCs) expressing Nras(G12D/+) serve as MPN-initiating cells. They undergo moderate hyperproliferation with increased self-renewal. The aberrant Nras(G12D/+) HSC function is associated with hyperactivation of ERK1/2 in HSCs. Conversely, downregulation of MEK/ERK by pharmacologic and genetic approaches attenuates the cycling of Nras(G12D/+) HSCs and prevents the expansion of Nras(G12D/+) HSCs and myeloid progenitors. Our data delineate critical mechanisms of oncogenic Nras signaling in HSC function and leukemogenesis.