Genetic Determinants of Peripheral Artery Disease

Polygenic Prediction of Peripheral Artery Disease and Major Adverse Limb Events

Importance

Peripheral artery disease (PAD) is a heritable atherosclerotic condition associated with functional decline and high risk for limb loss. With growing knowledge of the genetic basis for PAD and related risk factors, there is potential opportunity to identify individuals at high risk using polygenic risk scores (PRSs).

Objective

To develop a novel integrated, multiancestry polygenic score for PAD (PRS-PAD) and evaluate its risk estimation for PAD and major adverse limb events in 3 populations.

Design, Setting, and Participants

This longitudinal cohort study was conducted among individuals with genotyping and electronic health record data in the UK Biobank (2006-2021), All of Us (AoU, 2018-2022), and the Mass General Brigham Biobank (MGBB, 2010-2023). Data were analyzed from July 2023 to February 2025.

Exposures

PRS-PAD, previously published PAD polygenic scores, and clinical risk factors.

Main Outcomes and Measures

The primary outcomes were PAD and major adverse limb events, defined as a surrogate of major amputation and acute limb ischemia.

Results

The study populations included 400 533 individuals from the UK Biobank (median [IQR] age, 58.2 [45.0-71.4] years; 216 215 female participants [53.9%]), 218 500 from AoU (median [IQR] age, 53.6 [37.7-65.0] years; 132 647 female participants [60.7%]), and 32 982 from MGBB (median [IQR] age, 56.0 [32.0-80.0] years; 18 277 female participants [55.4%]). In the UK Biobank validation cohort, PRS-PAD was associated with an odds ratio [OR] per SD increase of 1.63 (95% CI, 1.60-1.68; P < .001). After adjusting for clinical risk factors, the OR for the top 20% of PRS-PAD was 1.68 (95% CI, 1.62-1.74; P < .001) compared to the remainder of the population. Among PAD cases without a history of diabetes, smoking, or chronic kidney disease (n = 3645), 1097 individuals (30.1%) had a high PRS-PAD (top 20%). In incident disease analysis, PRS-PAD improved discrimination (C statistic, 0.761), which was nearly equivalent to the performances of diabetes (C statistic, 0.760) and smoking (C statistic, 0.765). Among individuals with prevalent PAD, high PRS-PAD was associated with an increased risk of incident major adverse limb events in the UK Biobank (hazard ratio [HR], 1.75; 95% CI, 1.18-2.57; P = .005), MGBB (HR, 1.56; 95% CI, 1.06-2.30; P = .02), and AoU (HR, 1.57; 95% CI, 1.06-2.33; P = .03).

Conclusions and Relevance

This cohort study develops a new PRS that stratifies risk of PAD and adverse limb outcomes. Incorporating polygenic risk into PAD care warrants further investigation to guide screening and tailor management to prevent major adverse limb events.

Elevated Remnant and LDL Cholesterol and the Risk of Peripheral Artery Disease: A Mendelian Randomization Study

BACKGROUND

Elevated remnant cholesterol and low-density lipoprotein (LDL) cholesterol both increase the risk of coronary artery disease (CAD), but it is not known if the same is true for peripheral artery disease (PAD).

OBJECTIVES

This study tested the hypothesis that elevated remnant cholesterol and LDL cholesterol, each independent of the other, have causal effects on risk of PAD.

METHODS

The authors constructed genetic scores from variants near genes known to directly affect levels of remnant cholesterol and LDL cholesterol, identified through a genome-wide association study of individuals in the UK Biobank. Univariable (remnant cholesterol and LDL cholesterol genetic scores separately) and multivariable (remnant cholesterol and LDL cholesterol genetic scores combined) Mendelian randomization were used to estimate the causal effects of higher remnant cholesterol and LDL cholesterol levels on ORs for PAD (n = 38,414 cases and 758,308 controls) and CAD (n = 221,445 cases and 770,615 controls).

RESULTS

Increments in remnant and LDL genetic scores corresponding to 1 mmol/L (39 mg/dL) higher remnant and LDL cholesterol, respectively, were associated with univariable ORs for PAD of 2.72 (95% CI: 2.10-3.52) and 1.37 (95% CI: 1.25-1.51); corresponding multivariable ORs were 2.16 (95% CI: 1.49-3.12) and 1.14 (95% CI: 1.00-1.30). For CAD, corresponding univariable ORs were 2.92 (95% CI: 2.34-3.64) and 1.67 (95% CI: 1.56-1.79), whereas multivariable ORs were 1.86 (95% CI: 1.39-2.47) and 1.44 (95% CI: 1.29-1.60). Scaled to 1 SD increments in remnant cholesterol and LDL cholesterol, corresponding univariable ORs were 1.37 (95% CI: 1.27-1.49) and 1.29 (95% CI: 1.20-1.39) for PAD, and 1.40 (95% CI: 1.31-1.51) and 1.51 (95% CI: 1.43-1.59) for CAD; corresponding multivariable ORs were 1.28 (95% CI: 1.14-1.43) and 1.11 (95% CI: 1.00-1.23) for PAD, and 1.22 (95% CI: 1.11-1.33) and 1.34 (95% CI: 1.23-1.46) for CAD.

CONCLUSIONS

Elevated remnant cholesterol had a causal effect on risk of PAD even after accounting for elevated LDL cholesterol, whereas most of the causal effect of elevated LDL cholesterol on risk of PAD was dependent on simultaneously elevated remnant cholesterol. These results indicate that remnant cholesterol may be the major cholesterol fraction responsible for increased risk of PAD. Future studies should investigate the biological mechanisms behind these findings to find improved therapies for prevention and treatment of PAD.

ALKBH5 alleviates lower extremity arteriosclerosis by regulating ITGB1 demethylation and influencing macrophage polarization

Objective

M6A methylation-regulated macrophages play an important role in the occurrence and development of arteriosclerosis. However, their role in lower extremity arteriosclerosis remains unclear. Therefore, this study aims to explore the key factors that regulate arteriosclerosis methylation in the lower extremities and the mechanism by which they affect arteriosclerosis by influencing macrophage polarization.

Methods

The m6A methylation levels in peripheral blood mononuclear cells (PBMCs) of patients with lower extremity atherosclerosis was investigated using the Dot blot method. Additionally, the expression levels of RNA methyltransferases and demethylases were examined using ELISA and Western blotting. Inflammatory macrophages were established using RAW264.7 cells stimulated with LPS (100 ng/mL), and the expression of ALKBH5 and ITGB1 was evaluated using Western blotting. Immunofluorescence staining was conducted to assess the expression of M1 macrophage markers (F4/80+CD86) and M2 macrophage markers (F4/80+CD206) in renal tissue. ELISA was employed to measure the levels of cytokines (IL-6, IL-1β, TNF-a, IL-10, and TGF-β) and plasma lipid levels in mice. An atherosclerosis model was established in ApoE-/- mice through balloon pull surgery and high-fat feeding. Oil Red O staining and hematoxylin and eosin (HE) staining were performed to measure the area of atherosclerotic plaques and the size of the necrotic core in mouse femoral artery, respectively. Additionally, Starbase2.0 was used for downstream target gene prediction of ALKBH5. The half-life of ITGB1 was evaluated using RT-qPCR.

Results

The m6A methylation levels were significantly increased in PBMCs of patients with lower extremity atherosclerosis. Among them, the expression of the RNA demethylase ALKBH5 was the lowest in PBMCs of patients with lower extremity atherosclerosis. Further analysis revealed that ALKBH5 can alleviate the progression of lower extremity atherosclerosis and promote the polarization of M2 macrophages. ALKBH5 can reduce the stability of ITGB1 through demethylation. Mechanistically, ALKBH5 influences macrophage polarization and mitigates lower extremity atherosclerosis by affecting the demethylation of ITGB1.

Conclusion

ALKBH5 promotes M2 macrophage polarization and alleviates lower extremity atherosclerosis by regulating the demethylation of ITGB1. A deeper understanding of this process not only helps elucidate the molecular mechanisms of atherosclerosis but also provides possibilities for the development of new therapeutic strategies.

Developing technologies to assess vascular ageing: a roadmap from VascAgeNet

Vascular ageing (vascular ageing) is the deterioration of arterial structure and function which occurs naturally with age, and which can be accelerated with disease. Measurements of vascular ageing are emerging as markers of cardiovascular risk, with potential applications in disease diagnosis and prognosis, and for guiding treatments. However, vascular ageing is not yet routinely assessed in clinical practice. A key step towards this is the development of technologies to assess vascular ageing. In this Roadmap, experts discuss several aspects of this process, including: measurement technologies; the development pipeline; clinical applications; and future research directions. The Roadmap summarises the state of the art, outlines the major challenges to overcome, and identifies potential future research directions to address these challenges.

Racial and Socioeconomic Health Disparities in Peripheral Artery Disease

Peripheral artery disease (PAD) is a progressive atherosclerotic disease that causes lower extremity arterial stenosis or occlusion. Patients with PAD are at increased risk of myocardial infarction, stroke, limitations in ambulation, and amputation. Despite the advances in medicine and technology, the outcomes from PAD, including critical limb-threatening ischemia, acute limb ischemia amputation, and mortality, remain increased among specific racial and ethnic groups that have been historically marginalized in America, including Black, Hispanic, and American Indian individuals in the United States when compared with White persons. The purpose of this review is to summarize PAD literature that incorporates racial and ethnic disparities in PAD. There are a rising number of studies focused on the interface of racial and ethnic disparities and PAD. The majority of these studies are specifically focused on Black race, whereas there are limited studies focused on other minoritized racial and ethnic groups in the United States. The application of race and ethnicity has also been shown to play a synergistic role with socioeconomic status on PAD outcomes. Effective strategies focused on implementing policies that support quality measures and focus on social determinants of health have been shown to promote health equity and reduce disparities. Current evidence suggests that biological differences are less likely to be the leading cause of disparities in PAD between racial and ethnic groups compared with White Americans and supports a renewed focus on social determinants of health to achieve health equity.

The Role of Genetics in Managing Peripheral Arterial Disease

BACKGROUND

Genome wide association studies (GWAS) have allowed for a rapid increase in our understanding of the underlying genetics and biology of many diseases. By capitalizing on common genetic variation between individuals, GWAS can identify DNA variants associated with diseases of interest. A variety of statistical methods can be applied to GWAS results which allows for risk factor identification, stratification, and to identify potential treatments. Peripheral artery disease (PAD) is a common vascular disease that has been shown to have a strong genetic component. This article provides a review of the modern literature and our current understanding of the role of genetics in PAD.

METHODS

All available GWAS studies on PAD were reviewed. A literature search involving these studies was conducted and relevant articles applying the available GWAS data were summarized to provide a comprehensive review of our current understanding of the genetic component in PAD.

RESULTS

The largest available GWAS on PAD has identified 19 genome wide significant loci, with factor V Leiden and genes responsible for circulating lipoproteins being implicated in the development of PAD. Mendelian randomization (MR) studies have identified risk factors and causal associations with smoking, diabetes, and obesity and many other traits; protein-based MR has also identified circulating lipid and clotting factor levels associated with the incidence of PAD. Polygenic risk scores may allow for improved prediction of disease incidence and allow for early identification of at-risk patients but more work needs to be done to validate this approach.

CONCLUSIONS

Genetic epidemiology has allowed for an increased understanding of PAD in the past decade. Genome-wide association studies have led to improved detection of genetic contributions to PAD, and further genetic analyses have validated risk factors and may provide options for improved screening in at-risk populations. Ongoing biobank studies of chronic limb threatening ischemia patients and the increasing ancestral diversity in biobank enrollment will allow for even further exploration into the pathogenesis and progression of PAD.

Lipid-associated GWAS loci as important markers of the risk, severity, and clinical course of peripheral artery disease

BACKGROUND

This study investigated the relationship between lipid-associated loci identified through genome-wide association studies (GWAS) and the risk of peripheral artery disease (PAD), its severity, as well as clinical and laboratory features.

RESEARCH DESIGN AND METHODS

A study included 1263 unrelated Russian subjects, consisting of 620 patients diagnosed with PAD and 643 healthy controls. Thirteen single nucleotide polymorphisms (SNP) were genotyped using the MassArray-4 system.

RESULTS

Polymorphisms rs1689800, rs55730499 and rs881844 were found to be associated with an increased risk of PAD, whereas SNPs rs1883025, rs3136441, rs3764261 and rs6065906 showed protective effects against disease (Pperm ≤ 0.05). SNPs rs1689800, rs217406, rs1883025, and rs3136441 exhibited combined effects with cigarette smoking on the PAD risk (Pperm ≤ 0.05). Polymorphisms rs55730499 (beta = 0.124, Pperm = 0.04), rs9987289 (beta = 0.558, Pperm = 0.03), and rs881844 beta = -0.171, Pperm = 0.03) correlated with the ankle-brachial index. Multiple associations have been found between the SNPs and clinically significant characteristics, including disease severity, risk of gangrene, early disease onset, plasma procoagulant and atherogenic lipid changes (Pperm ≤ 0.05).

CONCLUSIONS

We identified novel genetic markers associated with PAD susceptibility and disease-related clinical and laboratory features. The identified biomarkers enhance the potential for predictive genetic testing related to the risk and progression of PAD, facilitating the integration of molecular diagnostics into clinical decision-making processes.

Advancements in Omics and Breakthrough Gene Therapies: A Glimpse into the Future of Peripheral Artery Disease

Peripheral artery disease (PAD), a highly prevalent global disease, associates with significant morbidity and mortality in affected patients. Despite progress in endovascular and open revascularization techniques for advanced PAD, these interventions grapple with elevated rates of arterial restenosis and vein graft failure attributed to intimal hyperplasia (IH). Novel multiomics technologies, coupled with sophisticated analyses tools recently powered by advances in artificial intelligence, have enabled the study of atherosclerosis and IH with unprecedented single-cell and spatial precision. Numerous studies have pinpointed gene hubs regulating pivotal atherogenic and atheroprotective signaling pathways as potential therapeutic candidates. Leveraging advancements in viral and nonviral gene therapy (GT) platforms, gene editing technologies, and cutting-edge biomaterial reservoirs for delivery uniquely positions us to develop safe, efficient, and targeted GTs for PAD-related diseases. Gene therapies appear particularly fitting for ex vivo genetic engineering of IH-resistant vein grafts. This manuscript highlights currently available state-of-the-art multiomics approaches, explores promising GT-based candidates, and details GT delivery modalities employed by our laboratory and others to thwart mid-term vein graft failure caused by IH, as well as other PAD-related conditions. The potential clinical translation of these targeted GTs holds the promise to revolutionize PAD treatment, thereby enhancing patients' quality of life and life expectancy.

Ancestry specific distribution of LPA Kringle IV-Type-2 genetic variants highlight associations to apo(a) copy number, glucose, and hypertension

Background

High Lp(a) levels contribute to atherosclerotic cardiovascular disease and are tightly regulated by the LPA gene . Lp(a) levels have an inverse correlation with LPA Kringle IV Type-2 (KIV-2) copy number (CN). Black (B) and Hispanic (H) individuals exhibit higher levels of Lp(a), and rates of CVD compared to non-Hispanic Whites (NHW). Therefore, we investigated genetic variations in the LPA KIV-2 region across three ancestries and their associations with metabolic risk factors.

Methods

Using published pipelines, we analyzed a multi-ethnic whole exome dataset comprising 3,817 participants from the Washington Heights and Inwood Columbia Aging Project (WHICAP): 886 [NHW (23%), 1,811 Caribbean (C) H (47%), and 1,120 B individuals (29%). Rare and common variants (alternative allele carrier frequency, CF < 0.01 or > 0.99 and 0.01 < CF < 0.99, respectively) were identified and KIV-2 CN estimated. The associations of variants and CN with history of heart disease, hypertension (HTN), stroke, lipid levels and clinical diagnosis of Alzheimer's disease (AD) was assessed. A small pilot provided in-silico validation of study findings.

Results

We report 1421 variants in the LPA KIV-2 repeat region, comprising 267 exonic and 1154 intronic variants. 61.4% of the exonic variants have not been previously described. Three novel exonic variants significantly increase the risk of HTN across all ethnic groups: 4785-C/A (frequency = 78%, odds ratio [OR] = 1.45, p = 0.032), 727-T/C (frequency = 96%, OR = 2.11, p = 0.032), and 723-A/G (frequency = 96%, OR = 1.97, p = 0.038). Additionally, six intronic variants showed associations with HTN: 166-G/A, 387-G/C, 402-G/A, 4527-A/T, 4541-G/A, and 4653-A/T. One intronic variant, 412-C/T, was associated with decreased blood glucose levels (frequency = 72%, β = -14.52, p = 0.02).Three of the associations were not affected after adjusting for LPA KIV-2 CN: 412-C/T (β = -14.2, p = 0.03), 166-G/A (OR = 1.41, p = 0.05), and 387-G/C (OR = 1.40, p = 0.05). KIV CN itself was significantly associated with 314 variants and was negatively correlated with plasma total cholesterol levels.

Conclusions

In three ancestry groups, we identify novel rare and common LPA KIV-2 region variants. We report new associations of variants with HTN and Glucose levels. These results underscore the genetic complexity of the LPA KIV-2 region in influencing cardiovascular and metabolic health, suggesting potential genetic regulation of pathways that can be studied for research and therapeutic interventions.

APOC1 rs445925 and rs4420638 polymorphic variants as genetic predictors of occlusive peripheral arterial disease of lower extremities

Aim. To study the involvement of APOC1 rs445925 and rs4420638 single nucleotide polymorphisms (SNP) in the development of occlusive peripheral arterial disease (PAD) of lower extremities.

Material and methods. The study included 1278 people, including 630 patients with occlusive PAD and 648 relatively healthy individuals. Genotyping of APOC1 rs445925 and rs4420638 SNPs was performed using the MassARRAY-4 genomic mass spectrometer. The analysis of the association of alleles, genotypes, haplotypes and diplotypes with the risk of occlusive PAD was performed using the statistical programs SNPStats, PLINK, v1.9 and STATISTICA 13.3. The adaptive permutation test was used to assess statistical significance of associations (Pperm).

Results. The rs445925-A (Pperm=1,0×10-6) and rs4420638-G (Pperm=0,006) alleles, as well as the rs445925-G/A-A/A (Pperm=1,0×10-6) and rs4420638-A/G-G/G (Pperm=0,006) genotypes were associated with an increased risk of occlusive PAD. The rs445925 polymorphism was also associated with the blood cholesterol level in patients with occlusive PAD (Pperm=0,04). The rs445925A-rs4420638A and rs445925A-rs4420638G haplotypes, as well as three APOC1 diplotypes, showed a pronounced relationship with a predisposition to occlusive PAD. In particular, the rs445925G/A×rs4420638A/A (odds ratio (OR) 6,59, 95% confidence interval (CI) 4,20-10,35, P=2,4×10-19) and rs445925G/A×rs4420638A/G (OR 4,24, 95% CI 2,23-8,03, P=2,0×10-6) diplotypes were associated with an increased risk of occlusive PAD. The rs445925G/G×rs4420638A/A diplotype had a protective effect on the disease development (OR 0,26, 95% CI 0,20-0,35, P=1,3×10-20). Associations of haplotypes with the severity of peripheral arterial stenosis of various locations were also revealed (P<0,05).

Conclusion. The study results established for the first time that APOC1 rs445925 and rs4420638 polymorphic variants are part of a genetic predisposition to occlusive PAD and have a significant effect on the severity of peripheral arterial stenosis. The molecular mechanisms underlying the identified genotypic associations can affect not only lipid metabolism disorders, but also the proliferation of immunocompetent cells, platelet activation and aggregation processes, inflammation and apoptosis.

Remnant Cholesterol, Not LDL Cholesterol, Explains Peripheral Artery Disease Risk Conferred by apoB: A Cohort Study

BACKGROUND

Elevated apoB-containing lipoproteins (=remnants+LDLs [low-density lipoproteins]) are a major risk factor for atherosclerotic cardiovascular disease, including peripheral artery disease (PAD) and myocardial infarction. We tested the hypothesis that remnants and LDL both explain part of the increased risk of PAD conferred by elevated apoB-containing lipoproteins. For comparison, we also studied the risk of chronic limb-threatening ischemia and myocardial infarction.

METHODS

apoB, remnant cholesterol, and LDL cholesterol were measured in 93 461 individuals without statin use at baseline from the Copenhagen General Population Study (2003-2015). During up to 15 years of follow-up, 1207 had PAD, 552 had chronic limb-threatening ischemia, and 2022 had myocardial infarction in the Danish National Patient Registry. Remnant and LDL cholesterol were calculated from a standard lipid profile. Remnant and LDL particle counts were additionally measured with nuclear magnetic resonance spectroscopy in 25 347 of the individuals. Results were replicated in 302 167 individuals without statin use from the UK Biobank (2004-2010).

RESULTS

In the Copenhagen General Population Study, multivariable adjusted hazard ratios for risk of PAD per 1 mmol/L (39 mg/dL) increment in remnant and LDL cholesterol were 1.9 (95% CI, 1.5-2.4) and 1.1 (95% CI, 1.0-1.2), respectively; corresponding results in the UK Biobank were 1.7 (95% CI, 1.4-2.1) and 0.9 (95% CI, 0.9-1.0), respectively. In the association from elevated apoB to increased risk of PAD, remnant and LDL cholesterol explained 73% (32%-100%) and 8% (0%-46%), respectively; corresponding results were 63% (30%-100%) and 0% (0%-33%) for risk of chronic limb-threatening ischemia and 41% (27%-55%) and 54% (38%-70%) for risk of myocardial infarction; results for remnant and LDL particle counts corroborated these findings.

CONCLUSIONS

PAD risk conferred by elevated apoB-containing lipoproteins was explained mainly by elevated remnants, while myocardial infarction risk was explained by both elevated remnants and LDL.

Unveiling the Genetic Footprint: Exploring Somatic Mutations in Peripheral Arterial Disease Progression

Peripheral arterial diseases (PADs) are complex cardiovascular conditions influenced by environmental factors and somatic mutations in multiple genes involved in hematopoiesis and inflammation. While traditional risk factors, such as smoking, hypercholesterolemia, and hypertension, have been extensively studied, the role of somatic mutations in PAD progression remains underexplored. The present article intends to provide a comprehensive commentary of the molecular mechanisms, genetic landscape, prognostic significance, and clinical implications of somatic mutations in PADs. The expansion of clonal hematopoiesis of indeterminate potential (CHIP) clones in the circulating blood, named clonal hematopoiesis (CH), leads to the infiltration of these clones into atherosclerotic plaques and the production of inflammatory cytokines, increasing the risk of cardiovascular diseases, including PADs. Furthermore, recent experimental evidence has demonstrated the involvement of somatically mutated TP53 genes with a high variant allele frequency (VAF) in PAD development and prognosis. This review delves into the relationship between CH and PADs, elucidating the prevalence, impact, and underlying mechanisms of this association. This understanding paves the way for novel therapeutic approaches targeting CHIP to promote tissue regeneration and improve outcomes in PAD patients. It emphasizes the need for further research to fully unravel the genetic footprint of the disease and highlights potential clinical implications. The findings presented in this article lay the foundation for personalized medicine approaches and open avenues for the development of targeted therapies based on somatic mutation profiling.

Admixture mapping of peripheral artery disease in a Dominican population reveals a putative risk locus on 2q35

Peripheral artery disease (PAD) is a form of atherosclerotic cardiovascular disease, affecting ∼8 million Americans, and is known to have racial and ethnic disparities. PAD has been reported to have a significantly higher prevalence in African Americans (AAs) compared to non-Hispanic European Americans (EAs). Hispanic/Latinos (HLs) have been reported to have lower or similar rates of PAD compared to EAs, despite having a paradoxically high burden of PAD risk factors; however, recent work suggests prevalence may differ between sub-groups. Here, we examined a large cohort of diverse adults in the BioMe biobank in New York City. We observed the prevalence of PAD at 1.7% in EAs vs. 8.5% and 9.4% in AAs and HLs, respectively, and among HL sub-groups, the prevalence was found at 11.4% and 11.5% in Puerto Rican and Dominican populations, respectively. Follow-up analysis that adjusted for common risk factors demonstrated that Dominicans had the highest increased risk for PAD relative to EAs [OR = 3.15 (95% CI 2.33-4.25), p < 6.44 × 10-14]. To investigate whether genetic factors may explain this increased risk, we performed admixture mapping by testing the association between local ancestry and PAD in Dominican BioMe participants (N = 1,813) separately from European, African, and Native American (NAT) continental ancestry tracts. The top association with PAD was an NAT ancestry tract at chromosome 2q35 [OR = 1.96 (SE = 0.16), p < 2.75 × 10-05) with 22.6% vs. 12.9% PAD prevalence in heterozygous NAT tract carriers versus non-carriers, respectively. Fine-mapping at this locus implicated tag SNP rs78529201 located within a long intergenic non-coding RNA (lincRNA) LINC00607, a gene expression regulator of key genes related to thrombosis and extracellular remodeling of endothelial cells, suggesting a putative link of the 2q35 locus to PAD etiology. Efforts to reproduce the signal in other Hispanic cohorts were unsuccessful. In summary, we showed how leveraging health system data helped understand nuances of PAD risk across HL sub-groups and admixture mapping approaches elucidated a putative risk locus in a Dominican population.

Health Disparities in Peripheral Artery Disease: A Scientific Statement From the American Heart Association

Peripheral artery disease (PAD) affects 200 million individuals worldwide. In the United States, certain demographic groups experience a disproportionately higher prevalence and clinical effect of PAD. The social and clinical effect of PAD includes higher rates of individual disability, depression, minor and major limb amputation along with cardiovascular and cerebrovascular events. The reasons behind the inequitable burden of PAD and inequitable delivery of care are both multifactorial and complex in nature, including systemic and structural inequity that exists within our society. Herein, we present an overview statement of the myriad variables that contribute to PAD disparities and conclude with a summary of potential novel solutions.

Admixture Mapping of Peripheral Artery Disease in a Dominican Population Reveals a Novel Risk Locus on 2q35

Peripheral artery disease (PAD) is a form of atherosclerotic cardiovascular disease, affecting ∼8 million Americans, and is known to have racial and ethnic disparities. PAD has been reported to have significantly higher prevalence in African Americans (AAs) compared to non-Hispanic European Americans (EAs). Hispanic/Latinos (HLs) have been reported to have lower or similar rates of PAD compared to EAs, despite having a paradoxically high burden of PAD risk factors, however recent work suggests prevalence may differ between sub-groups. Here we examined a large cohort of diverse adults in the Bio Me biobank in New York City (NYC). We observed the prevalence of PAD at 1.7% in EAs vs 8.5% and 9.4% in AAs and HLs, respectively; and among HL sub-groups, at 11.4% and 11.5% in Puerto Rican and Dominican populations, respectively. Follow-up analysis that adjusted for common risk factors demonstrated that Dominicans had the highest increased risk for PAD relative to EAs (OR=3.15 (95% CI 2.33-4.25), P <6.44×10 -14 ). To investigate whether genetic factors may explain this increased risk, we performed admixture mapping by testing the association between local ancestry (LA) and PAD in Dominican Bio Me participants (N=1,940) separately for European (EUR), African (AFR) and Native American (NAT) continental ancestry tracts. We identified a NAT ancestry tract at chromosome 2q35 that was significantly associated with PAD (OR=2.05 (95% CI 1.51-2.78), P <4.06×10 -6 ) with 22.5% vs 12.5% PAD prevalence in heterozygous NAT tract carriers versus non-carriers, respectively. Fine-mapping at this locus implicated tag SNP rs78529201 located within a long intergenic non-coding RNA (lincRNA) LINC00607 , a gene expression regulator of key genes related to thrombosis and extracellular remodeling of endothelial cells, suggesting a putative link of the 2q35 locus to PAD etiology. In summary, we showed how leveraging health systems data helped understand nuances of PAD risk across HL sub-groups and admixture mapping approaches elucidated a novel risk locus in a Dominican population.

Inflammatory and Prothrombotic Biomarkers, DNA Polymorphisms, MicroRNAs and Personalized Medicine for Patients with Peripheral Arterial Disease

Classical risk factors play a major role in the initiation and development of atherosclerosis. However, the estimation of risk for cardiovascular events based only on risk factors is often insufficient. Efforts have been made to identify biomarkers that indicate ongoing atherosclerosis. Among important circulating biomarkers associated with peripheral arterial disease (PAD) are inflammatory markers which are determined by the expression of different genes and epigenetic processes. Among these proinflammatory molecules, interleukin-6, C-reactive protein, several adhesion molecules, CD40 ligand, osteoprotegerin and others are associated with the presence and progression of PAD. Additionally, several circulating prothrombotic markers have a predictive value in PAD. Genetic polymorphisms significantly, albeit moderately, affect risk factors for PAD via altered lipoprotein metabolism, diabetes, arterial hypertension, smoking, inflammation and thrombosis. However, most of the risk variants for PAD are located in noncoding regions of the genome and their influence on gene expression remains to be explored. MicroRNAs (miRNAs) are single-stranded, noncoding RNAs that modulate gene expression at the post-transcriptional level. Patterns of miRNA expression, to some extent, vary in different atherosclerotic cardiovascular diseases. miRNAs appear to be useful in the detection of PAD and the prediction of progression and revascularization outcomes. In conclusion, taking into account one’s predisposition to PAD, i.e., DNA polymorphisms and miRNAs, together with circulating inflammatory and coagulation markers, holds promise for more accurate prediction models and personalized therapeutic options.

The Genetic Architecture of the Etiology of Lower Extremity Peripheral Artery Disease: Current Knowledge and Future Challenges in the Era of Genomic Medicine

Lower extremity artery disease (LEAD), caused by atherosclerotic obstruction of the arteries of the lower limb extremities, has exhibited an increase in mortality and morbidity worldwide. The phenotypic variability of LEAD is correlated with its complex, multifactorial etiology. In addition to traditional risk factors, it has been shown that the interaction between genetic factors (epistasis) or between genes and the environment potentially have an independent role in the development and progression of LEAD. In recent years, progress has been made in identifying genetic variants associated with LEAD, by Genome-Wide Association Studies (GWAS), Whole Exome Sequencing (WES) studies, and epigenetic profiling. The aim of this review is to present the current knowledge about the genetic factors involved in the etiopathogenic mechanisms of LEAD, as well as possible directions for future research. We analyzed data from the literature, starting with candidate gene-based association studies, and then continuing with extensive association studies, such as GWAS and WES. The results of these studies showed that the genetic architecture of LEAD is extremely heterogeneous. In the future, the identification of new genetic factors will allow for the development of targeted molecular therapies, and the use of polygenic risk scores (PRS) to identify individuals at an increased risk of LEAD will allow for early prophylactic measures and personalized therapy to improve their prognosis.

Phenotypic Causal Inference Using Genome-Wide Association Study Data: Mendelian Randomization and Beyond

statistics for genome-wide association studies (GWAS) are increasingly available for downstream analyses. Meanwhile, the popularity of causal inference methods has grown as we look to gather robust evidence for novel medical and public health interventions. This has led to the development of methods that use GWAS summary statistics for causal inference. Here, we describe these methods in order of their escalating complexity, from genetic associations to extensions of Mendelian randomization that consider thousands of phenotypes simultaneously. We also cover the assumptions and limitations of these approaches before considering the challenges faced by researchers performing causal inference using GWAS data. GWAS summary statistics constitute an important data source for causal inference research that offers a counterpoint to nongenetic methods when triangulating evidence. Continued efforts to address the challenges in using GWAS data for causal inference will allow the full impact of these approaches to be realized.