Publications by authors named "Nita A Limdi"

Purpose: To investigate the complexities of covering study-recommended medical care costs for individuals (in order to prevent lack of adherence due to financial reasons), which have received little attention.

Methods: We explored the deliberations, decisions, and challenges faced by the Electronic Medical Records and Genomics (eMERGE) Network during the implementation of a genomic research project recommending clinical care based on high-risk results defined largely by polygenic risk scores. Two surveys were disseminated to eMERGE sites: to identify preferences about payment for specific care recommendations (survey 1) and to understand the operational processes of covering medical care costs (survey 2).

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Kidney dysfunction is a major cause of mortality, but its genetic architecture remains elusive. In this study, we conducted a multiancestry genome-wide association study in 2.2 million individuals and identified 1026 (97 previously unknown) independent loci.

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Apart from ancestry, personal or environmental covariates may contribute to differences in polygenic score (PGS) performance. We analyzed the effects of covariate stratification and interaction on body mass index (BMI) PGS (PGS) across four cohorts of European (N = 491,111) and African (N = 21,612) ancestry. Stratifying on binary covariates and quintiles for continuous covariates, 18/62 covariates had significant and replicable R differences among strata.

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  • A study investigated how well a polygenic risk score (PRS) for systolic blood pressure (SBP) can predict patients' responses to antihypertensive treatment and the risk of treatment-resistant hypertension.
  • The research focused on participants from the GenHAT study, specifically Black individuals who were assigned to treatment groups involving chlorthalidone or lisinopril.
  • The main outcomes measured were changes in blood pressure after six months and the likelihood of being classified as treatment-resistant hypertension based on defined criteria.
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  • Warfarin dosing is affected by individual clinical and genetic factors, with a need to explore genetic variants specific to African populations for better dosing guidance.
  • A genome-wide association study (GWAS) focused on 989 warfarin-treated participants from Uganda, South Africa, and Zimbabwe, as well as African American cohorts, found significant genetic variants associated with warfarin response.
  • The study highlighted the importance of the CYP2C9 and VKORC1 genes and identified a new potential genetic locus (MALL) that may impact warfarin response, warranting further research to understand its biological relevance.
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  • Chronic kidney disease (CKD) affects about 1 in 7 adults in the U.S., especially African Americans who are more likely to suffer from it.
  • Scientists discovered that certain changes in DNA can help predict who might get CKD, focusing on specific sites in the DNA.
  • The study created a special score using these DNA changes to see how likely someone is to have CKD and found it works well for African Americans, suggesting it could help in checking kidney health in the future.
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Key Points: The predictive performance of an African ancestry–specific polygenic risk score (PRS) was comparable to a European ancestry–derived PRS for kidney traits. However, multi-ancestry PRSs outperform single-ancestry PRSs in Black American populations. Predictive accuracy of PRSs for CKD was improved with the use of race-free eGFR.

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Type 2 diabetes (T2D) is caused by both genetic and environmental factors and is associated with an increased risk of cardiorenal complications and mortality. Though disproportionately affected by the condition, African Americans (AA) are largely underrepresented in genetic studies of T2D, and few estimates of heritability have been calculated in this race group. Using genome-wide association study (GWAS) data paired with phenotypic data from ~ 19,300 AA participants of the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study, Genetics of Hypertension Associated Treatments (GenHAT) study, and the Electronic Medical Records and Genomics (eMERGE) network, we estimated narrow-sense heritability using two methods: Linkage-Disequilibrium Adjusted Kinships (LDAK) and Genome-Wide Complex Trait Analysis (GCTA).

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Article Synopsis
  • - Health equity means everyone has equal chances to achieve their best health, but human genomics research has not reflected the diversity of the population, leading to health disparities.
  • - The National Human Genome Research Institute (NHGRI) acknowledges these inequities and has gathered experts to provide recommendations and review the current state of health equity in genomics.
  • - This report outlines the gaps and opportunities in bridging human genomics with health equity, emphasizing the need for more diverse participation in genomics research to improve health outcomes for all.
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Apart from ancestry, personal or environmental covariates may contribute to differences in polygenic score (PGS) performance. We analyzed effects of covariate stratification and interaction on body mass index (BMI) PGS (PGS) across four cohorts of European (N=491,111) and African (N=21,612) ancestry. Stratifying on binary covariates and quintiles for continuous covariates, 18/62 covariates had significant and replicable R differences among strata.

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African Americans (AAs) have been underrepresented in polygenic risk score (PRS) studies. Here, we integrated genome-wide data from multiple observational studies on type 2 diabetes (T2D), encompassing a total of 101,987 AAs, to train and optimize an AA-focused T2D PRS (PRSAA), using a Bayesian polygenic modeling method. We further tested the score in three independent studies with a total of 7,275 AAs and compared the PRSAA with other published scores.

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Background: Despite direct oral anticoagulants (DOACs) being safer than warfarin for stroke prevention in atrial fibrillation (AF), major bleeding concerns persist. Most bleeding risk scores predate DOAC approval.

Objectives: This study aimed to compare the Age, history of Bleeding, and non-bleeding related Hospitalisation [ABH] score's performance-derived for DOAC-treated patients-with those of 5 other scores (Anticoagulation and Risk Factors in Atrial Fibrillation [ATRIA], Hypertension, Abnormal renal/liver function, Stroke, Bleeding history or predisposition, Labile international normalized ratio, Elderly [>65 years], Drugs/alcohol concomitantly [HAS-BLED], Hepatic, Hepatic or Renal Disease, Ethanol Abuse, Malignancy, Older Age, Reduced Platelet Count or Function, Re-Bleeding, Hypertension, Anemia, Genetic Factors, Excessive Fall Risk and Stroke [HEMORRHAGES], Outcomes Registry for Better Informed Treatment of Atrial Fibrillation [ORBIT-AF], and Congestive heart failure, Hypertension, Age ≥75 [doubled], Diabetes, Stroke [doubled]-Vascular disease, Age 65-74, Sex category [CHADS-VASc]) in predicting DOAC-related major bleeding in patients with AF.

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Objective: Developing targeted, culturally competent educational materials is critical for participant understanding of engagement in a large genomic study that uses computational pipelines to produce genome-informed risk assessments.

Materials And Methods: Guided by the Smerecnik framework that theorizes understanding of multifactorial genetic disease through 3 knowledge types, we developed English and Spanish infographics for individuals enrolled in the Electronic Medical Records and Genomics Network. Infographics were developed to explain concepts in lay language and visualizations.

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Polygenic risk scores (PRS) have potential to improve health care by identifying individuals that have elevated risk for common complex conditions. Use of PRS in clinical practice, however, requires careful assessment of the needs and capabilities of patients, providers, and health care systems. The electronic Medical Records and Genomics (eMERGE) network is conducting a collaborative study which will return PRS to 25,000 pediatric and adult participants.

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Although major advancements have been made in the therapeutics for people with cystic fibrosis (PwCF), many still require the use of multiple medications to manage acute exacerbations of disease and maintain health. Iterative trial and error processes of pharmacotherapeutic management can be optimized by assessing and incorporating pharmacogenetics. For 82 PwCF, we reviewed 2 years of medication use and response history and interrogated metabolizer status for common pharmacogenes, revealing 3336 medication exposure events (MEEs) to 286 unique medications.

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Article Synopsis
  • The study aims to assess the risk of common diseases by considering clinical, monogenic, and polygenic factors, which may be reflected in an individual's family history.
  • The eMERGE network is enrolling 25,000 individuals in a prospective study to create and return a comprehensive risk assessment report (GIRA) that includes various genetic risk factors and care recommendations.
  • The GIRA report provides actionable guidelines for health care based on genetic data, highlighting the importance of integrating genetic risk assessment into routine health care practices.
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  • Polygenic risk scores (PRS) show promise for precision medicine but face challenges in generalizing across different ancestry groups and ages.
  • The study generated body mass index (BMI) PRS using genome-wide association study (GWAS) data from various ancestry groups, finding that performance improved with cross-ancestry data, particularly for African ancestry participants.
  • Additionally, the research highlighted that PRS were less effective in children compared to teenagers and adults, and identified links between BMI PRS and comorbidities like type 2 diabetes and coronary atherosclerosis.
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Abdominal aortic aneurysms (AAA) are common enlargements of the abdominal aorta which can grow larger until rupture, often leading to death. Detection of AAA is often by ultrasonography and screening recommendations are mostly directed at men over 65 with a smoking history. Recent large-scale genome-wide association studies have identified genetic loci associated with AAA risk.

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Atrial fibrillation (AF) is the leading cause of ischemic stroke and treatment has focused on reducing this risk through anticoagulation. Direct Oral Anticoagulants (DOACs) are the first-line guideline-recommended therapy since they are as effective and overall safer than warfarin in preventing AF-related stroke. Although patients bleed less from DOACs compared to warfarin, bleeding remains the primary safety concern with this therapy.

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Black patients suffer worse outcomes after percutaneous coronary intervention (PCI) than White patients. Inequities in antiplatelet prescribing may contribute to this health disparity. We compared P2Y inhibitor prescribing by race following CYP2C19 genotyping to guide antiplatelet therapy selection after PCI.

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Background: Some but not all African-Americans (AA) who carry nephropathy risk variants () develop kidney failure (end-stage kidney disease, ESKD). To identify genetic modifiers, we assessed gene-gene interactions in a large prospective cohort of the REasons for Geographic and Racial Differences in Stroke (REGARDS) study.

Methods: Genotypes from 8,074 AA participants were obtained from Illumina Infinium Multi-Ethnic AMR/AFR Extended BeadChip.

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Arachidonate 5-lipoxygenase (ALOX5)-derived leukotrienes are primary signals of leukocyte activation and inflammation in response to ischemic cardiac injury (MI; myocardial infarction). Using risk-free male C57BL/6J and ALOX5-null mice (8-12 wk), we quantitated leukocytes and ALOX5-derived bioactive lipids of the infarcted left ventricle (LV) and spleen to measure the physiological inflammation and cardiac repair. Our results showed that ALOX5 endogenously generates specialized pro-resolving mediators (SPMs) that facilitate cardiac repair post-MI.

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Hypertension is a leading risk factor for cardiovascular disease mortality. African Americans (AAs) have the highest prevalence of hypertension in the United States, and to alleviate the burden of hypertension in this population, better control of blood pressure (BP) is needed. Previous studies have shown considerable interpersonal differences in BP response to antihypertensive treatment, suggesting a genetic component.

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Oral anticoagulants (OACs) are commonly used to reduce the risk of venous thromboembolism and the risk of stroke in patients with atrial fibrillation. Endorsed by the American Heart Association, American College of Cardiology, and the European Society of Cardiology, direct oral anticoagulants (DOACs) have displaced warfarin as the OAC of choice for both conditions, due to improved safety profiles, fewer drug-drug and drug-diet interactions, and lack of monitoring requirements. Despite their widespread use and improved safety over warfarin, DOAC-related bleeding remains a major concern for patients.

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Background: Type 2 diabetes (T2D) is a worldwide scourge caused by both genetic and environmental risk factors that disproportionately afflicts communities of color. Leveraging existing large-scale genome-wide association studies (GWAS), polygenic risk scores (PRS) have shown promise to complement established clinical risk factors and intervention paradigms, and improve early diagnosis and prevention of T2D. However, to date, T2D PRS have been most widely developed and validated in individuals of European descent.

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