Genetic ancestry is associated with measures of subclinical atherosclerosis in African Americans: the Jackson Heart Study

Heterogeneity of Lipoprotein(a) Levels Among Hispanic or Latino Individuals Residing in the US

Importance

Lipoprotein(a) (Lp[a]) is a genetically determined risk-enhancing factor for atherosclerotic cardiovascular disease (ASCVD). The Lp(a) distribution among the diverse Hispanic or Latino community residing in the US has not been previously described, to the authors' knowledge.

Objective

To determine the distribution of Lp(a) levels across a large cohort of diverse Hispanic or Latino adults living in the US and by key demographic groups.

Design, Setting, and Participants

The Hispanic Community Health Study/Study of Latinos (HCHS/SOL) is a prospective, population-based, cohort study of diverse Hispanic or Latino adults living in the US. At screening, participants aged 18 to 74 years were recruited between 2008 and 2011 from 4 US metropolitan areas (Bronx, New York; Chicago, Illinois; Miami, Florida; San Diego, California). HCHS/SOL included 16 415 noninstitutionalized adults recruited through probability sampling of randomly selected households. The study population represents Hispanic or Latino participants from diverse self-identified geographic and cultural backgrounds: Central American, Cuban, Dominican, Mexican, Puerto Rican, and South American. This study evaluated a subset of HCHS/SOL participants who underwent Lp(a) measurement. Sampling weights and surveys methods were used to account for HCHS/SOL sampling design. Data for this study were analyzed from April 2021 to April 2023.

Exposure

Lp(a) molar concentration was measured by a particle-enhanced turbidimetric assay with minimized sensitivity to apolipoprotein(a) size variation.

Main Outcome and Measure

Lp(a) quintiles were compared using analysis of variance among key demographic groups, including self-identified Hispanic or Latino background. Median percentage genetic ancestry (Amerindian, European, West African) were compared across Lp(a) quintiles.

Results

Lp(a) molar concentration was measured in 16 117 participants (mean [SD] age, 41 [14.8] years; 9680 female [52%]; 1704 Central American [7.7%], 2313 Cuban [21.1%], 1436 Dominican [10.3%], 6395 Mexican [39.1%], 2652 Puerto Rican [16.6%], 1051 South American [5.1%]). Median (IQR) Lp(a) level was 19.7 (7.4-59.7) nmol/L. Across Hispanic or Latino background groups, there was significant heterogeneity in median Lp(a) levels ranging from 12 to 41 nmol/L in those reporting a Mexican vs Dominican background. Median (IQR) West African genetic ancestry was lowest in the first quintile of Lp(a) level and highest in the fifth quintile (5.5% [3.4%-12.9%] and 12.1% [5.0%-32.5%]; respectively; P < .001), whereas the converse was seen for Amerindian ancestry (32.8% [9.9%-53.2%] and 10.7% [4.9%-30.7%], respectively; P < .001).

Conclusions and Relevance

Results of this cohort study suggest that differences in Lp(a) level distribution across the diverse US Hispanic or Latino population may carry important implications for the use of Lp(a) level in ASCVD risk assessment for this group. Cardiovascular outcomes data are needed to better understand the clinical impact of differences in Lp(a) levels by Hispanic or Latino background.

The association of racial and ethnic disparities and frailty in geriatric patients undergoing revascularization for peripheral artery disease

Frailty is defined as a state of decreased physiologic reserve contributing to functional decline and adverse outcomes. Racial disparities in frail patients have been described sparsely in the literature. We aimed to assess whether race influences frailty status in geriatric patients undergoing revascularization for peripheral artery disease (PAD) with chronic limb-threatening ischemia (CLTI). A 5-year analysis of the National Surgical Quality Improvement Program database included all geriatric (65 years and older) patients who underwent revascularization for lower extremity PAD with CLTI. The frailty index was calculated using a 11-variable modified frailty index and a cutoff of 0.27 indicated frail status. The primary outcome was an association of race or ethnicity with frailty status. We included 7,837 geriatric patients who underwent a surgical procedure (open: 55.2%) for PAD with CLTI. Mean age of patients was 75.4 years, 63.8% were male, 24.1% (n = 1,889) were frail, and 21.8% (n = 1,710) were African American (AA). Overall complication rate was 11.2% (n = 909) and overall mortality rate was 1.9% (n = 148). AA patients were more likely to be frail than White patients (29.6% v 23.9%; P = .03). AA and Hispanic patients were more likely to have complications (P = .03 and P = .001) and require readmission (P = .015 and P = .001) compared with White and non-Hispanic patients, respectively. Frail AA and frail Hispanic patients were more likely to have 30-day complications and readmission compared with frail White and frail non-Hispanic patients, respectively. Race and ethnicity influence frailty status in geriatric patients with PAD and CLTI. These disparities exist regardless of age, sex, comorbid conditions, and type of operative procedure. Additional studies are needed to highlight disparities by race and ethnicity to identify potentially modifiable risk factors to improve outcomes.

Non-linear machine learning models incorporating SNPs and PRS improve polygenic prediction in diverse human populations

Polygenic risk scores (PRS) are commonly used to quantify the inherited susceptibility for a trait, yet they fail to account for non-linear and interaction effects between single nucleotide polymorphisms (SNPs). We address this via a machine learning approach, validated in nine complex phenotypes in a multi-ancestry population. We use an ensemble method of SNP selection followed by gradient boosted trees (XGBoost) to allow for non-linearities and interaction effects. We compare our results to the standard, linear PRS model developed using PRSice, LDpred2, and lassosum2. Combining a PRS as a feature in an XGBoost model results in a relative increase in the percentage variance explained compared to the standard linear PRS model by 22% for height, 27% for HDL cholesterol, 43% for body mass index, 50% for sleep duration, 58% for systolic blood pressure, 64% for total cholesterol, 66% for triglycerides, 77% for LDL cholesterol, and 100% for diastolic blood pressure. Multi-ancestry trained models perform similarly to specific racial/ethnic group trained models and are consistently superior to the standard linear PRS models. This work demonstrates an effective method to account for non-linearities and interaction effects in genetics-based prediction models.

Disparities in peripheral artery disease care: A review and call for action

Peripheral artery disease (PAD), the pathophysiologic narrowing of arterial blood vessels of the lower leg due to atherosclerosis, is a highly prevalent disease that affects more than 6 million individuals 40 years and older in the United States, with sharp increases in prevalence with age. Morbidity and mortality rates in patients with PAD range from 30% to 70% during the 5- to 15-year period after diagnosis and PAD is associated with poor health outcomes and reduced functionality and quality of life. Despite advances in medical, endovascular, and open surgical techniques, there is striking variation in care among population subgroups defined by sex, race and ethnicity, and socioeconomic status, with concomitant differences in preoperative medication optimization, amputation risk, and overall health outcomes. We reviewed studies from 1995 to 2021 to provide a comprehensive analysis of the current impact of disparities on the treatment and management of PAD and offer action items that require strategic partnership with primary care providers, researchers, patients, and their communities. With new technologies and collaborative approaches, optimal management across all population subgroups is possible.

Multiethnic Genome-Wide Association Study of Subclinical Atherosclerosis in Individuals With Type 2 Diabetes

BACKGROUND

Coronary artery calcification (CAC) and carotid artery intima-media thickness (cIMT) are measures of subclinical atherosclerosis in asymptomatic individuals and strong risk factors for cardiovascular disease. Type 2 diabetes (T2D) is an independent cardiovascular disease risk factor that accelerates atherosclerosis.

METHODS

We performed meta-analyses of genome-wide association studies in up to 2500 T2D individuals of European ancestry (EA) and 1590 T2D individuals of African ancestry with or without exclusion of prevalent cardiovascular disease, for CAC measured by cardiac computed tomography, and 3608 individuals of EA and 838 individuals of African ancestry with T2D for cIMT measured by ultrasonography within the CHARGE (Cohorts for Heart and Aging Research in Genomic Epidemiology) Consortium.

RESULTS

We replicated 2 loci (rs9369640 and rs9349379 near PHACTR1 and rs10757278 near CDKN2B) for CAC and one locus for cIMT (rs7412 and rs445925 near APOE-APOC1) that were previously reported in the general EA populations. We identified one novel CAC locus (rs8000449 near CSNK1A1L/LINC00547/POSTN at 13q13.3) at P=2.0×10-8 in EA. No additional loci were identified with the meta-analyses of EA and African ancestry. The expression quantitative trait loci analysis with nearby expressed genes derived from arterial wall and metabolic tissues from the Genotype-Tissue Expression project pinpoints POSTN, encoding a matricellular protein involved in bone formation and bone matrix organization, as the potential candidate gene at this locus. In addition, we found significant associations (P<3.1×10-4) for 3 previously reported coronary artery disease loci for these subclinical atherosclerotic phenotypes (rs2891168 near CDKN2B-AS1 and rs11170820 near FLJ12825 for CAC, and rs7412 near APOE for cIMT).

CONCLUSIONS

Our results provide potential biological mechanisms that could link CAC and cIMT to increased cardiovascular disease risk in individuals with T2D.

Association of Genetic West African Ancestry, Blood Pressure Response to Therapy, and Cardiovascular Risk Among Self-Reported Black Individuals in the Systolic Blood Pressure Reduction Intervention Trial (SPRINT)

IMPORTANCE

Self-identified Black race is associated with higher hypertension prevalence and worse blood pressure (BP) control compared with other race/ethnic groups. The contribution of genetic West African ancestry to these racial disparities appears not to have been completely determined.

OBJECTIVE

To determine the association between the proportion of West African ancestry with the response to antihypertensive medication, BP control, kidney function, and risk of adverse cardiovascular (CV) events among self-identified Black individuals in the Systolic Blood Pressure Intervention Trial (SPRINT).

DESIGN, SETTING, AND PARTICIPANTS

This post hoc analysis of the SPRINT trial incorporated data from a multicenter study of self-identified Black participants with available West African ancestry proportion, estimated using 106 biallelic autosomal ancestry informative genetic markers. Recruitment started on October 20, 2010, and ended on August 20, 2015. Data were analyzed from May 2020 to September 2020.

MAIN OUTCOMES AND MEASURES

Trajectories of BP and kidney function parameters on follow-up of the trial were assessed across tertiles of the proportion of West African ancestry using linear mixed-effect modeling after adjustment for potential confounders. Multivariable adjusted Cox models evaluated the association of West African ancestry with the risk of composite CV events (nonfatal myocardial infarction, CV death, and heart failure event).

RESULTS

Among 2466 participants in the current analysis (1122 women [45.5%]; median West African ancestry, 81% [interquartile range, 73%-87%]), there were 120 composite CV events (4.9%) over a mean (SD) of 3.2 (0.9) years of follow-up. At baseline, mean (SD) high-density lipoprotein cholesterol levels were higher (tertile 3: 56.5 [15.0] mg/dL vs tertile 1: 54.2 [14.9] mg/dL; P = .006), smoking prevalence (never smoking: tertile 3: 367 [47.9%] vs tertile 1: 372 [42.2%]; P = .009) and mean (SD) Framingham Risk scores (tertile 3: 16.7 [9.7] vs tertile 1: 18.1 [10.2]; P = .01) were lower, and baseline BP was not different across increasing tertiles of West African ancestry. On follow-up, there was no evidence of differences in longitudinal trajectories of BP, kidney function parameters, or left ventricular mass (Cornell voltage by electrocardiogram) across tertiles of West African ancestry in either intensive or standard treatment arms. In adjusted Cox models, higher West African ancestry was associated with a lower risk of a composite CV event after adjustment for potential confounders (adjusted hazard ratio per 5% higher West African ancestry, 0.92 [95% CI, 0.85-0.99]).

CONCLUSIONS AND RELEVANCE

Among self-reported Black individuals enrolled in SPRINT, the trajectories of BP, kidney function, and left ventricular mass over time were not different across tertiles of the proportion of West African ancestry. A higher proportion of West African ancestry was associated with a modestly lower risk for CV events. These findings suggest that extrinsic and structural societal factors, more than genetic ancestry, may be the major drivers of the well-established racial disparity in cardiovascular health associated with hypertension.

Leveraging genetic ancestry to study health disparities

Research to understand human genomic variation and its implications in health has great potential to contribute in the reduction of health disparities. Biological anthropology can play important roles in genomics and health disparities research using a biocultural approach. This paper argues that racial/ethnic categories should not be used as a surrogate for sociocultural factors or global genomic clusters in biomedical research or clinical settings, because of the high genetic heterogeneity that exists within traditional racial/ethnic groups. Genetic ancestry is used to show variation in ancestral genomic contributions to recently admixed populations in the United States, such as African Americans and Hispanic/Latino Americans. Genetic ancestry estimates are also used to examine the relationship between ancestry‐related biological and sociocultural factors affecting health disparities. To localize areas of genomes that contribute to health disparities, admixture mapping and genome‐wide association studies (GWAS) are often used. Recent GWAS have identified many genetic variants that are highly differentiated among human populations that are associated with disease risk. Some of these are population‐specific variants. Many of these variants may impact disease risk and help explain a portion of the difference in disease burden among racial/ethnic groups. Genetic ancestry is also of particular interest in precision medicine and disparities in drug efficacy and outcomes. By using genetic ancestry, we can learn about potential biological differences that may contribute to the heterogeneity observed across self‐reported racial groups.

Special Issue: Race reconciled II: Interpreting and communicating biological variation and race in 2021

APOL1 Genetic Variants Are Associated with Serum-Oxidized Low-Density Lipoprotein Levels and Subclinical Atherosclerosis in South African CKD Patients

INTRODUCTION

Apolipoprotein L1 (APOL1) plays an important role in cholesterol metabolism and attenuation of low-density lipoprotein (LDL) oxidation. While protecting against Trypanosoma brucei rhodesiense infection, APOL1 risk alleles confer greater risk for CKD and cardiovascular disease among patients of African descent.

OBJECTIVES

We investigated whether APOL1 risk variants are associated with atherosclerosis and oxidized LDL (OxLDL) levels among black South African CKD patients.

METHODS

A cross-sectional study of 120 adult CKD patients and 40 controls was undertaken. DNA samples of participants were genotyped for APOL1 G1 and G2 variants. High-sensitivity C-reactive protein, serum lipids, and OxLDL levels were measured, and carotid doppler ultrasonography was performed on all participants.

RESULTS

APOL1 alleles rs73885319, rs60910145, and rs71785313 had minor allele frequencies of 9.2, 8.8, and 17.5%, respectively, in the patients, and 8.8, 8.8, and 13.8%, respectively, in the controls. Of the 9 patients with 2 APOL1 risk alleles, 77.8% were compound G1/G2 heterozygotes and 22.2% were G2 homozygotes. Carriers of at least 1 APOL1 risk allele had a 3-fold increased risk of subclinical atherosclerosis (odds ratio 3.19; 95% confidence interval: 1.64-6.19; p = 0.01) compared to individuals with no risk alleles. Patients with 1 or 2 APOL1 risk alleles showed a significant increase in OxLDL levels when compared with those without the APOL1 risk allele.

CONCLUSION

These findings suggest an increased risk for atherosclerosis in carriers of a single APOL1 risk variant, and the presence of APOL1 risk variants was associated with increased serum OxLDL levels in black South African CKD patients.

Association of West African ancestry and blood pressure control among African Americans taking antihypertensive medication in the Jackson Heart Study

African Americans have a wide range of continental genetic ancestry. It is unclear whether racial differences in blood pressure (BP) control are related to ancestral background. The authors analyzed data from the Jackson Heart Study, a cohort exclusively comprised of self-identified African Americans, to assess the association between estimated West African ancestry (WAA) and BP control (systolic and diastolic BP < 140/90 mm Hg). Three nested modified Poisson regression models were used to calculate prevalence ratios for BP control associated with the three upper quartiles, separately, vs the lowest quartile of West African ancestry. The authors analyzed data from 1658 participants with hypertension who reported taking all of their antihypertensive medications in the previous 24 hours. WAA was estimated using 389 ancestry informative markers and categorized into quartiles (Q1: <73.7%, Q2: >73.7%-81.0%, Q3: >81.0%-86.3%, and Q4: >86.3%). The proportion of participants with controlled BP in the lowest-to-highest WAA quartile was 75.2%, 76.1%, 76.6%, and 74.4%. The prevalence ratios (95% CI) for controlled BP comparing Q2, Q3, and Q4 to Q1 of WAA were 1.00 (0.93-1.08), 1.02 (0.94-1.10), and 0.99 (0.91-1.07), respectively. Among African Americans in the Jackson Heart Study taking antihypertensive medication, BP control rates did not differ across quartiles of WAA.

Racial Disparities in the Cardiac Computed Tomography Assessment of Coronary Artery Disease: Does Gender Matter

Coronary heart disease (CHD) represents a significant healthcare burden in terms of hospital resources, morbidity, and mortality. Primary prevention and early detection of risk factors for the development of CHD are pivotal to successful intervention programs and prognostication. Yet, there remains a paucity of evidence regarding differences in the assessment of these risk factors and the tools of assessment among different ethnicities. We conducted a narrative review to assess the utility of cardiac computed tomography, particularly coronary artery calcification (CAC), in different ethnicities. We also looked to see whether age, sex, comorbidities, and genetic background have peculiar influences on CAC. In this review, we highlight some of the pivotal studies regarding the question of CAC in relation to the development of CHD among different ethnicities. We identify several key trends in the literature showing that although African Americans have high rates of CHD, their risk of CAC may be relatively lower compared with other ethnicities. Similarly, South Asian patients may be at a high risk for adverse cardiac events due to elevated CAC. We also note that several studies are limited by small sample size and were based on 1 large cohort study. Future studies should include a large international prospective cohort to truly evaluate the effects of ethnicity on CAC and CHD risk. To appropriately apply CAC in the clinical practice, the variations in its scoring based on a subject's age, sex, comorbidity, and ethnicity should be addressed and interpreted beforehand.

Associations of coronary artery calcified plaque density with mortality in type 2 diabetes: the Diabetes Heart Study

Background

Coronary artery calcified plaque (CAC) is strongly predictive of cardiovascular disease (CVD) events and mortality, both in general populations and individuals with type 2 diabetes at high risk for CVD. CAC is typically reported as an Agatston score, which is weighted for increased plaque density. However, the role of CAC density in CVD risk prediction, independently and with CAC volume, remains unclear.

Methods

We examined the role of CAC density in individuals with type 2 diabetes from the family-based Diabetes Heart Study and the African American-Diabetes Heart Study. CAC density was calculated as mass divided by volume, and associations with incident all-cause and CVD mortality [median follow-up 10.2 years European Americans (n = 902, n = 286 deceased), 5.2 years African Americans (n = 552, n = 93 deceased)] were examined using Cox proportional hazards models, independently and in models adjusted for CAC volume.

Results

In European Americans, CAC density, like Agatston score and volume, was consistently associated with increased risk of all-cause and CVD mortality (p ≤ 0.002) in models adjusted for age, sex, statin use, total cholesterol, HDL, systolic blood pressure, high blood pressure medication use, and current smoking. However, these associations were no longer significant when models were additionally adjusted for CAC volume. CAC density was not significantly associated with mortality, either alone or adjusted for CAC volume, in African Americans.

Conclusions

CAC density is not associated with mortality independent from CAC volume in European Americans and African Americans with type 2 diabetes.

Electronic supplementary material

The online version of this article (10.1186/s12933-018-0714-z) contains supplementary material, which is available to authorized users.

West African Ancestry and Nocturnal Blood Pressure in African Americans: The Jackson Heart Study

BACKGROUND

African Americans have a higher prevalence of nocturnal hypertension and nondipping blood pressure than European Americans, but the genetic contribution to these racial differences remains unclear. We assessed the association of the percentage West African genetic ancestry with nocturnal hypertension and nondipping blood pressure in 932 African Americans from the Jackson Heart Study.

METHODS

Using percentage West African ancestry determined from 389 ancestry informative markers, participants were categorized into tertiles (tertile 1 [low]: <79.3%, tertile 2: ≥79.3-86.3%, and tertile 3 [high]: >86.3%). Nocturnal hypertension was defined as mean nighttime (midnight-6 am) systolic (SBP)/diastolic blood pressure ≥120/70 mm Hg. Nondipping blood pressure was defined as mean nighttime-to-daytime (10 am-8 pm) SBP ratio >0.90.

RESULTS

Nocturnal hypertension was present in 57.9% of participants; 66.6% had nondipping blood pressure. The mean age was 59.4 years, 32.8% were male, and 56.0% were taking antihypertensive medication. The prevalence ratios (95% confidence interval) adjusted for age, sex, cardiovascular disease risk factors, and socioeconomic and psychosocial factors comparing participants with moderate and high to those with low percentage West African ancestry for nocturnal hypertension were 0.98 (0.87-1.10) and 0.95 (0.84-1.08), respectively, and for nondipping blood pressure was 0.96 (0.86-1.07) and 0.98 (0.88-1.09), respectively.

CONCLUSIONS

West African ancestry was not associated with nocturnal hypertension and nondipping blood pressure among African Americans. While rare genetic variants cannot be ruled out, these data highlight the need to better understand how environmental and behavioral factors contribute to differences in nocturnal blood pressure among African Americans compared with European Americans.

Association of variant in the ADIPOQ gene and functional study for its role in atherosclerosis

The burden of atherosclerosis is heritable and associated with elevated risk of developing CVDs. Here, we evaluated genetic variants of adiponectin (ADIPOQ) gene, which has important role in anti- atherosclerosis, with risk of atherosclerosis among a large Chinese population. Our results show that rs74577862 was significantly associated with risk of atherosclerosis (OR=2.08; 95%CI=1.48-2.91; P=2.2×10-5). When stratified by atherosclerosis site, rs74577862 was associated with increased risk of both carotid atherosclerosis (OR=2.03; 95%CI=1.35-3.06; P=6.3×10-4) and coronary atherosclerosis (OR=2.11; 95%CI=1.44-3.09; P=1.1×10-4). In addition, we also carried out site-directed mutagenesis and dual-luciferase reporter assay to confirm the positive finding, which presents a significant decrease in luciferase expression for the reconstructed plasmid with rs74577862 A allele in comparison to the one with G allele (P<0.001). Real-time PCR also confirmed the findings above. These results strongly suggest that the functional SNP, ADIPOQ rs74577862 might contribute to atherosclerosis susceptibility.

Less Than Ideal Cardiovascular Health Is Associated With Shorter Leukocyte Telomere Length: The National Health and Nutrition Examination Surveys, 1999-2002

Background

The associations between individual cardiovascular disease risk factors and leukocyte telomere length (LTL) have been inconclusive. We investigated the association between LTL and overall cardiovascular health (CVH) as defined by the American Heart Association and whether the association is modified by sex and race/ethnicity.

Methods and Results

We included 5194 adults (aged ≥20) from the National Health and Nutrition Examination Survey 1999–2002. CVH was defined as a composite score of the 7 metrics (smoking, physical activity, diet, body mass index, blood pressure, total cholesterol, and fasting blood glucose) and categorized as “poor,” “intermediate,” and “ideal.” LTL was assayed from whole blood using the quantitative polymerase chain reaction method relative to standard reference DNA. Multivariable linear regression models were used to estimate the association between CVH and log‐transformed LTL. We found strong graded association between CVH and LTL in the overall sample, with evidence of dose‐response relationship (P for trend=0.013). Individuals with poor and intermediate CVH had significantly shorter LTL than individuals with ideal CVH (−3.4% [95% CI=−6.0%, −0.8%] and −2.4% [−4.4%, −0.3%], respectively), after adjustment for demographic variables, socioeconomic status, and C‐reactive protein. The association was stronger in women (−6.6% [−10.2%, −2.9%] for poor vs ideal CVH) and non‐Hispanic whites (−4.3% [−7.1%, −1.4%] for poor vs ideal CVH).

Conclusions

The findings suggest that less‐than‐ideal CVH is associated with shorter LTL, but this association varies by sex and race/ethnicity. Future longitudinal research is needed to elucidate the mechanisms that underlie the association between CVH and LTL.