Contribution of Rare and Common Genetic Variants to Plasma Lipid Levels and Carotid Stiffness and Geometry: A Substudy of the Paris Prospective Study 3

Genomic study of maternal lipid traits in early pregnancy concurs with four known adult lipid loci

BACKGROUND

Blood lipids during pregnancy are associated with cardiovascular diseases and adverse pregnancy outcomes. Genome-wide association studies (GWAS) in predominantly male European ancestry populations have identified genetic loci associated with blood lipid levels. However, the genetic architecture of blood lipids in pregnant women remains poorly understood.

OBJECTIVE

Our goal was to identify genetic loci associated with blood lipid levels among pregnant women from diverse ancestry groups and to evaluate whether previously known lipid loci in predominantly European adults are transferable to pregnant women.

METHODS

The trans-ancestry GWAS were conducted on serum levels of total cholesterol, high-density lipoprotein cholesterol (HDL), low-density lipoprotein cholesterol (LDL) and triglycerides during first trimester among pregnant women from four population groups (608 European-, 623 African-, 552 Hispanic- and 235 East Asian-Americans) recruited in the NICHD Fetal Growth Studies cohort. The four GWAS summary statistics were combined using trans-ancestry meta-analysis approaches that account for genetic heterogeneity among populations.

RESULTS

Loci in CELSR2 and APOE were genome-wide significantly associated (p-value < 5×10-8) with total cholesterol and LDL levels. Loci near CETP and ABCA1 approached genome-wide significant association with HDL (p-value = 2.97×10-7 and 9.71×10-8, respectively). Less than 20% of previously known adult lipid loci were transferable to pregnant women.

CONCLUSION

This trans-ancestry GWAS meta-analysis in pregnant women identified associations that concur with four known adult lipid loci. Limited replication of known lipid-loci from predominantly European study populations to pregnant women underlines the need for genomic studies of lipids in ancestrally diverse pregnant women.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov, NCT00912132.

Identification of risk loci for primary aldosteronism in genome-wide association studies

Primary aldosteronism affects up to 10% of hypertensive patients and is responsible for treatment resistance and increased cardiovascular risk. Here we perform a genome-wide association study in a discovery cohort of 562 cases and 950 controls and identify three main loci on chromosomes 1, 13 and X; associations on chromosome 1 and 13 are replicated in a second cohort and confirmed by a meta-analysis involving 1162 cases and 3296 controls. The association on chromosome 13 is specific to men and stronger in bilateral adrenal hyperplasia than aldosterone producing adenoma. Candidate genes located within the two loci, CASZ1 and RXFP2, are expressed in human and mouse adrenals in different cell clusters. Their overexpression in adrenocortical cells suppresses mineralocorticoid output under basal and stimulated conditions, without affecting cortisol biosynthesis. Our study identifies the first risk loci for primary aldosteronism and highlights new mechanisms for the development of aldosterone excess.

Internal Carotid Artery Angle Variations are Poorly Explained by Vascular Risk Factors: The Northern Manhattan Study

OBJECTIVES

The internal carotid artery (ICA) angle of origin may contribute to atherogenesis by altered hemodynamics. We aim to determine the contribution of vascular risk factors and arterial wall changes to ICA angle variations.

METHODS

We analyzed 1,065 stroke-free participants from the population-based Northern Manhattan Study who underwent B-mode ultrasound (mean age 68.7±8.9 years; 59% women). ICA angle was estimated at the intersection between the common carotid artery and the ICA center line projections. Narrower external angles translating into greater carotid bifurcation bending were considered unfavorable. Linear regression models were fitted to assess the relationship between ICA angle and demographics, vascular risk factors, and arterial wall changes including carotid intima-media thickness (cIMT) and plaque presence.

RESULTS

ICA angles were narrower on the left compared to the right side (153±15.4 degrees versus 161.4±12.7 degrees, p<0.01). Mean cIMT was 0.9±0.1 mm and 54.3% had at least one plaque. ICA angle was not associated with cIMT or plaque presence. Unfavorable left and right ICA angles were associated with advanced age (per 10-year increase β=-1.6; p=0.01, and -1.3; p=0.03, respectively) and being Black participant (β=-4.6; p<0.01 and -2.9; p=0.04, respectively), while unfavorable left ICA angle was associated with being female (β=-2.8; p=0.03) and increased diastolic blood pressure (per 10 mmHg increase β=-2.1; p<0.01). Overall, studied factors explained less than 10% of the variance in ICA angle (left R2=0.07; right R2=0.05).

CONCLUSION

Only a small portion of ICA angle variation were explained by demographics, vascular risk factors and arterial wall changes. Whether ICA angle is determined by other environmental or genetic factors, and is an independent risk factor for atherogenesis, requires further investigation.

Sleep Apnea is Associated With Accelerated Vascular Aging: Results From 2 European Community-Based Cohort Studies

Background The mechanisms underlying the association between obstructive sleep apnea (OSA) and cardiovascular disease may include accelerated vascular aging. The aim was to compare the magnitude of vascular aging in patients with high versus low risk of OSA. Methods and Results In 2 community-based studies, the PPS3 (Paris Prospective Study 3) and the Maastricht Study, high risk of OSA was determined with the Berlin questionnaire (a screening questionnaire for OSA). We assessed carotid artery properties (carotid intima-media thickness, Young's elastic modulus, carotid-femoral pulse wave velocity, carotid pulse wave velocity, carotid diameter using high precision ultrasound echography), and carotid-femoral pulse wave velocity (in the Maastricht Study only). Regression coefficients were estimated on pooled data using multivariate linear regression. A total of 8615 participants without prior cardiovascular disease were included (6840 from PPS3, 62% men, mean age 59.5±6.2 years, and 1775 from the Maastricht Study, 51% men, 58.9±8.1 years). Overall, high risk of OSA prevalence was 16.8% (n=1150) in PPS3 and 23.8% (n=423) in the Maastricht Study. A high risk of OSA was associated with greater carotid intima-media thickness (β=0.21; 0.17-0.26), Young's elastic modulus (β=0.21; 0.17-0.25), carotid-femoral pulse wave velocity (β=0.24; 0.14-0.34), carotid pulse wave velocity (β=0.31; 0.26-0.35), and carotid diameter (β=0.43; 0.38-0.48), after adjustment for age, sex, total cholesterol, smoking, education level, diabetes mellitus, heart rate, and study site. Consistent associations were observed after additional adjustments for mean blood pressure, body mass index, or antihypertensive medications. Conclusions These data lend support for accelerated vascular aging in individuals with high risk of OSA. This may, at least in part, underlie the association between OSA and cardiovascular disease.

The Role of the ATP-Binding Cassette A1 (ABCA1) in Human Disease

Cholesterol homeostasis is essential in normal physiology of all cells. One of several proteins involved in cholesterol homeostasis is the ATP-binding cassette transporter A1 (ABCA1), a transmembrane protein widely expressed in many tissues. One of its main functions is the efflux of intracellular free cholesterol and phospholipids across the plasma membrane to combine with apolipoproteins, mainly apolipoprotein A-I (Apo A-I), forming nascent high-density lipoprotein-cholesterol (HDL-C) particles, the first step of reverse cholesterol transport (RCT). In addition, ABCA1 regulates cholesterol and phospholipid content in the plasma membrane affecting lipid rafts, microparticle (MP) formation and cell signaling. Thus, it is not surprising that impaired ABCA1 function and altered cholesterol homeostasis may affect many different organs and is involved in the pathophysiology of a broad array of diseases. This review describes evidence obtained from animal models, human studies and genetic variation explaining how ABCA1 is involved in dyslipidemia, coronary heart disease (CHD), type 2 diabetes (T2D), thrombosis, neurological disorders, age-related macular degeneration (AMD), glaucoma, viral infections and in cancer progression.

Hyperglycemia and arterial stiffness across two generations

OBJECTIVE

Hyperglycemia and diabetes mellitus associate with arterial stiffness. This observational study aimed to investigate such links in two related generations from a population-based study.

METHODS

Data from 2640 participants in the ongoing Malmö Offspring Study, Sweden, was used. The participants were direct descendants, that is, parents (median age 52.5 years) and children (26.9 years). In linear regressions, arterial stiffness measured through carotid--femoral pulse wave velocity was associated with markers of glucose metabolism (fasting glucose, glycated hemoglobin, skin autoflourescence of Advanced Glycation End products), adjusted for age, sex, smoking, BMI, lipids, SBP and antihypertensive medication. Analysis was first performed in all participants and then separately in each generation. T-tests with diabetes mellitus as the grouping variable were performed for all participants and per generation.

RESULTS

In all participants, pulse wave velocity was significantly associated with glucose (β = 0.007, P = 0.018) and hemoglobin (β = 0.017, P < 0.001), but not with autoflourescence. Stratified by generation, arterial stiffness was associated with glucose (β = 0.013, P = 0.008) and glycated hemoglobin (β = 0.022, P < 0.001) only in parents. Mean pulse speed differed between participants with and without diabetes in the total group (mean difference 1.7 m/s, P < 0.001), as well as within each generation (parents: 1.3 m/s; P < 0.001, and children: 0.7 m/s; P = 0.040).

CONCLUSION

Impaired glucose metabolism and arterial stiffness were significantly associated only in the parental generation, indicating the influence of hyperglycemia on vascular aging. However, carotid--femoral pulse wave velocity differed significantly between participants with or without diabetes mellitus in both generations, suggesting that diabetes might negatively affect arterial stiffness also at a younger age.

Targeted sequencing of linkage region in Dominican families implicates PRIMA1 and the SPATA7-PTPN21-ZC3H14-EML5-TTC8 locus in carotid-intima media thickness and atherosclerotic events

Carotid intima-media thickness (cIMT) is a subclinical marker for atherosclerosis. Previously, we reported a quantitative trait locus (QTL) for total cIMT on chromosome 14q and identified PRiMA1, FOXN3 and CCDC88C as candidate genes using a common variants (CVs)-based approach. Herein, we further evaluated the genetic contribution of the QTL to cIMT by resequencing. We sequenced all exons within the QTL and genomic regions of PRiMA1, FOXN3 and CCDC88C in Dominican families with evidence for linkage to the QTL. Unrelated Dominicans from the Northern Manhattan Study (NOMAS) were used for validation. Single-variant-based and gene-based analyses were performed for CVs and rare variants (RVs). The strongest evidence for association with CVs was found in PRiMA1 (p = 8.2 × 10⁻⁵ in families, p = 0.01 in NOMAS at rs12587586), and in the five-gene cluster SPATA7-PTPN21-ZC3H14-EML5-TTC8 locus (p = 1.3 × 10⁻⁴ in families, p = 0.01 in NOMAS at rs2274736). No evidence for association with RVs was found in PRiMA1. The top marker from previous study in PRiMA1 (rs7152362) was associated with fewer atherosclerotic events (OR = 0.67; p = 0.02 in NOMAS) and smaller cIMT (β = −0.58, p = 2.8 × 10⁻⁴ in Family). Within the five-gene cluster, evidence for association was found for exonic RVs (p = 0.02 in families, p = 0.28 in NOMAS), which was enriched among RVs with higher functional potentials (p = 0.05 in NOMAS for RVs in the top functional tertile). In summary, targeted resequencing provided validation and novel insights into the genetic architecture of cIMT, suggesting stronger effects for RVs with higher functional potentials. Furthermore, our data support the clinical relevance of CVs associated with subclinical atherosclerosis.

A multilocus genetic risk score is associated with arterial stiffness in hypertensive patients: the CARE NORTH study

INTRODUCTION

Arterial stiffness is recognized as an intermediate phenotype and predictor of cardiovascular disease. Arterial stiffness is complex in origin with contributions from lifestyle and genetic factors. However, the association between single nucleotide polymorphisms (SNPs) and arterial stiffness remains unclear.

OBJECTIVE

The aim is to assess whether a multilocus genetic risk score (GRS), composed of selected SNPs linked to cardiovascular traits and outcomes, is associated with arterial stiffness in patients with hypertension.

DESIGN AND METHODS

This study included 730 participants derived from the CARE NORTH study. The arterial stiffness was evaluated by carotid-femoral pulse wave velocity (cfPWV). An adjusted linear regression was used to evaluate the association between cfPWV and each individual SNP using multiple genetic models. The association between a constructed GRS and cfPWV was tested in an unadjusted and adjusted model.

RESULTS

We selected 13 SNPs found to be associated with cfPWV (P < .05): 6 SNPs in additive, 4 SNPs in recessive and 3 SNPs in dominant mode of inheritance. The GRS based on these SNPs was positively associated with cfPWV both in unadjusted and adjusted models (β = 0.2 m/s, 95% CI 0.11 - 0.29, P = 7.6 × 10 and β = 0.22 m/s, 95% CI 0.15 - 0.28, P = 1.4 × 10, respectively). The GRS explained an additional 3.6% cfPWV variance above clinical covariates.

CONCLUSION

We demonstrate that the GRS composed of 13 SNPs related to cardiovascular phenotypes is associated with an increased arterial stiffness in hypertensive patients. Our findings may help to clarify genetic basis of arterial stiffening and provide insight into mechanisms underlying this phenotype.

Lipid-related genetic polymorphisms significantly modulate the association between lipids and disability progression in multiple sclerosis

OBJECTIVE

To investigate whether lipid-related or body mass index (BMI)-related common genetic polymorphisms modulate the associations between serum lipid levels, BMI and disability progression in multiple sclerosis (MS).

METHODS

The association between disability progression (annualised Expanded Disability Status Scale (EDSS) change over 5 years, ΔEDSS) and lipid-related or BMI-related genetic polymorphisms was evaluated in a longitudinal cohort (n=184), diagnosed with MS. We constructed a cumulative genetic risk score (CGRS) of associated polymorphisms (p<0.05) and examined the interactions between the CGRS and lipid levels (measured at baseline) in predicting ΔEDSS. All analyses were conducted using linear regression.

RESULTS

Five lipid polymorphisms (rs2013208, rs9488822, rs17173637, rs10401969 and rs2277862) and one BMI polymorphism (rs2033529) were nominally associated with ΔEDSS. The constructed lipid CGRS showed a significant, dose-dependent association with ΔEDSS (p_trend=1.4×10^-6), such that participants having ≥6 risk alleles progressed 0.38 EDSS points per year faster compared with those having ≤3. This CGRS model explained 16% of the variance in ΔEDSS. We also found significant interactions between the CGRS and lipid levels in modulating ΔEDSS, including high-density lipoprotein (HDL; p_interaction=0.005) and total cholesterol:high-density lipoprotein ratio (TC:HDL; p_interaction=0.030). The combined model (combination of CGRS and the lipid parameter) explained 26% of the disability variance for HDL and 27% for TC:HDL.

INTERPRETATION

In this prospective cohort study, both lipid levels and lipid-related polymorphisms individually and jointly were associated with significantly increased disability progression in MS. These results indicate that these polymorphisms and tagged genes might be potential points of intervention to moderate disability progression.

Body Silhouette Trajectories Across the Lifespan and Vascular Aging

Vascular aging is a major contributor to cardiovascular disease and can be quantified by higher carotid stiffness, intima-media thickness and diameter, and hypertension. Weight gain across the lifetime may be an important, modifiable determinant of vascular aging. We therefore aimed to assess lifetime body silhouette trajectories (a marker of weight change across the lifespan) in relation to vascular aging in late adulthood. We used cross-sectional data from a community-based cohort study (n=8243; age, 59.4; 38.7% women). A linear mixed model was used to assess trajectories of recalled body silhouettes from age 8 to 45 years. We assessed carotid artery properties (ultrasonography), resting hypertension (blood pressure ≥140/90 mm Hg or use of antihypertensives), and exaggerated exercise blood pressure, a marker of masked hypertension (systolic blood pressure ≥150 mm Hg during submaximal exercise) at study recruitment when the participants were 50 to 75 years of age. We identified 5 distinct body silhouette trajectories: lean stable (32.0%), lean increase (11.1%), moderate stable (32.5%), lean-marked increase (16.3%), and heavy stable (8.1%). Compared with individuals in the lean-stable trajectory, those in the moderate-stable, lean-marked increase, and heavy-stable trajectories had higher carotid stiffness, intima-media thickness and diameter (odds ratios between 1.23 and 2.10 for highest quartile versus lowest quartile of manifestations of vascular aging; P<0.05) and were more likely to have resting hypertension and exaggerated exercise blood pressure, after adjustment for potential confounders (odds ratios between 1.31 and 1.60; P<0.05). Vascular aging was most prominent among individuals who were lean in early life but markedly gained weight during young adulthood and among those who were heavy in early life and maintained weight.

Carotid Artery Stiffness and Incident Depressive Symptoms: The Paris Prospective Study III

BACKGROUND

Arterial stiffness may contribute to late-life depression via cerebral microvascular damage, but evidence is scarce. No longitudinal study has evaluated the association between arterial stiffness and risk of depressive symptoms. Therefore, we investigated the association between carotid artery stiffness and incident depressive symptoms in a large community-based cohort study.

METHODS

This longitudinal study included 7013 participants (mean age 59.7 ± 6.3 years; 35.8% women) free of depressive symptoms at baseline. Carotid artery stiffness (high-resolution echo tracking) was determined at baseline. Presence of depressive symptoms was determined at baseline and at 4 and 6 years of follow-up, and was defined as a score ≥7 on the validated Questionnaire of Depression, Second Version, Abridged and/or new use of antidepressant medication. Logistic regression and generalized estimating equations were used.

RESULTS

In total, 6.9% (n = 484) of the participants had incident depressive symptoms. Individuals in the lowest tertile of carotid distensibility coefficient (indicating greater carotid artery stiffness) compared with those in the highest tertile had a higher risk of incident depressive symptoms (odds ratio: 1.43; 95% confidence interval: 1.10-1.87), after adjustment for age, sex, living alone, education, lifestyle, cardiovascular risk factors, and baseline Questionnaire of Depression, Second Version, Abridged scores. Results were qualitatively similar when we used carotid Young's elastic modulus as a measure of carotid stiffness instead of carotid distensibility coefficient, and when we used generalized estimating equations instead of logistic regression.

CONCLUSIONS

Greater carotid stiffness is associated with a higher incidence of depressive symptoms. This supports the hypothesis that carotid stiffness may contribute to the development of late-life depression.

Carotid Artery Atherosclerosis: A Review on Heritability and Genetics

Carotid atherosclerosis (CAS) is associated with increased cardiovascular risk, and therefore, assessing the genetic versus environmental background of CAS traits is of key importance. Carotid intima-media-thickness and plaque characteristics seem to be moderately heritable, with remarkable differences in both heritability and presence or severity of these traits among ethnicities. Although the considerable role of additive genetic effects is obvious, based on the results so far, there is an important emphasis on non-shared environmental factors as well. We aimed to collect and summarize the papers that investigate twin and family studies assessing the phenotypic variance attributable to genetic associations with CAS. Genes in relation to CAS markers were overviewed with a focus on genetic association studies and genome-wide association studies. Although the role of certain genes is confirmed by studies conducted on large populations and meta-analyses, many of them show conflicting results. A great focus should be on future studies elucidating the exact pathomechanism of these genes in CAS in order to imply them as novel therapeutic targets.

Family history of cardiometabolic diseases and its association with arterial stiffness in the Malmö Diet Cancer cohort

OBJECTIVE

Arterial stiffening increases with age and is associated with increased cardiovascular risk. Several risk factors have been shown to predict the development of arterial stiffening; however, a positive family history (FH+) of cardiometabolic disease (CMD) and hypertension has not been extensively studied. We hypothesize that FH+ of CMD plays a significant role in the development of arterial stiffening in offspring.

METHODS

We used data from the population-based Malmö Diet Cancer study (n = 3056) examined in 1992-1996 and again in 2007-2012. Several variables were analysed, including anthropometrics, carotid-femoral pulse wave velocity and FH+. The association between FH+ of CMD and arterial stiffening in the offspring was analysed with analysis of covariance in SPSS. FH+ was subdivided into three categories: family history for cardiovascular events (FH-CVEs), family history for diabetes mellitus type 2 (FH-DM2) and family history for hypertension (FH-HT). The first analysis of covariance-model was adjusted for age, sex, mean arterial pressure and heart rate; the second model additionally adjusted for self-reported medical history in the offspring.

RESULTS

Data indicated that FH-CVE (F = 14.64, P < 0.001), FH-DM2 (F = 18.57, P < 0.001) and FH-HT (F = 13.92, P < 0.001) all significantly increased carotid-femoral pulse wave velocity levels. The results remained when additional adjustment was made for confounders and for self-reported CMD in the index participants, respectively, for FH-CVE (F = 12.47, P < 0.001), FH-DM2 (F = 7.62, P = 0.006) as well as for FH-HT (F = 7.30, P = 0.007).

CONCLUSION

These findings indicate that a FH+ of cardiometabolic conditions and hypertension affects arterial stiffness in offspring independently of haemodynamic factors and self-reported CMD in the offspring without sex differences.

Vascular Smooth Muscle Cells and Arterial Stiffening: Relevance in Development, Aging, and Disease

The cushioning function of large arteries encompasses distension during systole and recoil during diastole which transforms pulsatile flow into a steady flow in the microcirculation. Arterial stiffness, the inverse of distensibility, has been implicated in various etiologies of chronic common and monogenic cardiovascular diseases and is a major cause of morbidity and mortality globally. The first components that contribute to arterial stiffening are extracellular matrix (ECM) proteins that support the mechanical load, while the second important components are vascular smooth muscle cells (VSMCs), which not only regulate actomyosin interactions for contraction but mediate also mechanotransduction in cell-ECM homeostasis. Eventually, VSMC plasticity and signaling in both conductance and resistance arteries are highly relevant to the physiology of normal and early vascular aging. This review summarizes current concepts of central pressure and tensile pulsatile circumferential stress as key mechanical determinants of arterial wall remodeling, cell-ECM interactions depending mainly on the architecture of cytoskeletal proteins and focal adhesion, the large/small arteries cross-talk that gives rise to target organ damage, and inflammatory pathways leading to calcification or atherosclerosis. We further speculate on the contribution of cellular stiffness along the arterial tree to vascular wall stiffness. In addition, this review provides the latest advances in the identification of gene variants affecting arterial stiffening. Now that important hemodynamic and molecular mechanisms of arterial stiffness have been elucidated, and the complex interplay between ECM, cells, and sensors identified, further research should study their potential to halt or to reverse the development of arterial stiffness.

Protein S Heerlen mutation heterozygosity is associated with venous thrombosis risk

Hereditary Protein S (PS) deficiency is a rare coagulation disorder associated with an increased risk of venous thrombosis (VT). The PS Heerlen (PSH) mutation is a rare S501P mutation that was initially considered to be a neutral polymorphism. However, it has been later shown that PSH has a reduced half-life in vivo which may explain the association of PSH heterozygosity with mildly reduced levels of plasma free PS (FPS). Whether the risk of VT is increased in PSH carriers remains unknown. We analyzed the association of PSH (rs121918472 A/G) with VT in 4,173 VT patients and 5,970 healthy individuals from four independent case-control studies. Quantitative determination of FPS levels was performed in a subsample of 1257 VT patients. In the investigated populations, the AG genotype was associated with an increased VT risk of 6.57 [4.06–10.64] (p = 1.73 10⁻¹⁴). In VT patients in whom PS deficiency was excluded, plasma FPS levels were significantly lower in individuals with PSH when compared to those without [72 + 13 vs 91 + 21 UI/dL; p = 1.86 10⁻⁶, mean + SD for PSH carriers (n = 21) or controls (n = 1236) respectively]. We provide strong evidence that the rare PSH variant is associated with VT in unselected individuals.

Carotid Bifurcation Geometry and Atherosclerosis

Hemodynamic changes occurring at the initial segments of the arterial bifurcations appear to play an important role in the development of atherosclerotic plaque. Therefore, arterial geometry might be a potential marker for atherosclerosis. Considerable evidence suggests that geometry can influence local hemodynamics at the carotid bifurcation contributing to the development of atheroma. Bifurcation angle, differences in the area ratios including the flare, proximal curvature, sinus bulb width, and tortuosity of the internal or external carotid artery have been listed as potential contributory elements. These morphometric details have been studied not only in postmortem examination but also with the help of imaging modalities such as ultrasound, digital subtraction angiography, computed tomography angiography, and the assistance of computational models and magnetic resonance angiography. The establishment of certain anatomical and geometrical details in addition to traditional risk factors may help in the identification of patients at high risk of developing carotid artery disease. We reviewed the literature to highlight the evidence on the importance of various geometrical details in the development of carotid atheroma and to suggest areas of future research.

PHACTR1 Is a Genetic Susceptibility Locus for Fibromuscular Dysplasia Supporting Its Complex Genetic Pattern of Inheritance

Fibromuscular dysplasia (FMD) is a nonatherosclerotic vascular disease leading to stenosis, dissection and aneurysm affecting mainly the renal and cerebrovascular arteries. FMD is often an underdiagnosed cause of hypertension and stroke, has higher prevalence in females (~80%) but its pathophysiology is unclear. We analyzed ~26K common variants (MAF>0.05) generated by exome-chip arrays in 249 FMD patients and 689 controls. We replicated 13 loci (P<10-4) in 402 cases and 2,537 controls and confirmed an association between FMD and a variant in the phosphatase and actin regulator 1 gene (PHACTR1). Three additional case control cohorts including 512 cases and 669 replicated this result and overall reached the genomic level of significance (OR = 1.39, P = 7.4×10-10, 1,154 cases and 3,895 controls). The top variant, rs9349379, is intronic to PHACTR1, a risk locus for coronary artery disease, migraine, and cervical artery dissection. The analyses of geometrical parameters of carotids from ~2,500 healthy volunteers indicate higher intima media thickness (P = 1.97×10-4) and wall to lumen ratio (P = 0.002) in rs9349379-A carriers, suggesting indices of carotid hypertrophy previously described in carotids of FMD patients. Immunohistochemistry detected PHACTR1 in endothelium and smooth muscle cells of FMD and normal human carotids. The expression of PHACTR1 by genotypes in primary human fibroblasts showed higher expression in rs9349379-A carriers (N = 86, P = 0.003). Phactr1 knockdown in zebrafish resulted in dilated vessels indicating subtle impaired vascular development. We report the first susceptibility locus for FMD and provide evidence for a complex genetic pattern of inheritance and indices of shared pathophysiology between FMD and other cardiovascular and neurovascular diseases.