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Background: The risk of arterial diseases may be elevated among family members of individuals having multifocal fibromuscular dysplasia (FMD). We sought to investigate the risk of arterial diseases in families of individuals with FMD., Methods: Family histories for 73 probands with FMD were obtained, which included an analysis of 463 total first-degree relatives focusing on FMD and related arterial disorders. A polygenic risk score for FMD (PRS FMD ) was constructed from prior genome-wide association findings of 584 FMD cases and 7139 controls and evaluated for association with an abdominal aortic aneurysm (AAA) in a cohort of 9693 AAA cases and 294 049 controls. A previously published PRS AAA was also assessed among the FMD cases and controls., Results: Of all first degree relatives of probands, 9.3% were diagnosed with FMD, aneurysms, and dissections. Aneurysmal disease occurred in 60.5% of affected relatives and 5.6% of all relatives. Among 227 female first-degree relatives of probands, 4.8% (11) had FMD, representing a relative risk (RR) FMD of 1.5 ([95% CI, 0.75-2.8]; P =0.19) compared with the estimated population prevalence of 3.3%, though not of statistical significance. Of all fathers of FMD probands, 11% had AAAs resulting in a RR AAA of 2.3 ([95% CI, 1.12-4.6]; P =0.014) compared with population estimates. The PRS FMD was found to be associated with an AAA (odds ratio, 1.03 [95% CI, 1.01-1.05]; P =2.6×10 -3 ), and the PRS AAA was found to be associated with FMD (odds ratio, 1.53 [95% CI, 1.2-1.9]; P =9.0×10 -5 ) as well., Conclusions: FMD and AAAs seem to be sex-dimorphic manifestations of a heritable arterial disease with a partially shared complex genetic architecture. Excess risk of having an AAA according to a family history of FMD may justify screening in family members of individuals having FMD.

Objective: While rare variants in the COL5A1 gene have been associated with classical Ehlers-Danlos syndrome and rarely with arterial dissections, recurrent variants in COL5A1 underlying a systemic arteriopathy have not been described. Monogenic forms of multifocal fibromuscular dysplasia (mFMD) have not been previously defined. Approach and Results: We studied 4 independent probands with the COL5A1 pathogenic variant c.1540G>A, p.(Gly514Ser) who presented with arterial aneurysms, dissections, tortuosity, and mFMD affecting multiple arteries. Arterial medial fibroplasia and smooth muscle cell disorganization were confirmed histologically. The COL5A1 c.1540G>A variant is predicted to be pathogenic in silico and absent in gnomAD. The c.1540G>A variant is on a shared 160.1 kb haplotype with 0.4% frequency in Europeans. Furthermore, exome sequencing data from a cohort of 264 individuals with mFMD were examined for COL5A1 variants. In this mFMD cohort, COL5A1 c.1540G>A and 6 additional relatively rare COL5A1 variants predicted to be deleterious in silico were identified and were associated with arterial dissections ( P =0.005)., Conclusions: COL5A1 c.1540G>A is the first recurring variant recognized to be associated with arterial dissections and mFMD. This variant presents with a phenotype reminiscent of vascular Ehlers-Danlos syndrome. A shared haplotype among probands supports the existence of a common founder. Relatively rare COL5A1 genetic variants predicted to be deleterious by in silico analysis were identified in ≈2.7% of mFMD cases, and as they were enriched in patients with arterial dissections, may act as disease modifiers. Molecular testing for COL5A1 should be considered in patients with a phenotype overlapping with vascular Ehlers-Danlos syndrome and mFMD.

Background: We previously described a strong association between fibromuscular dysplasia (FMD) and spontaneous coronary artery dissection. Angiographic manifestations of coronary FMD aside from dissection were considered rare. However, we observed several coronary FMD angiographic abnormalities with corresponding optical coherence tomography abnormalities., Methods and Results: Baseline demographics and imaging of patients with suspected coronary FMD at Vancouver General Hospital were reviewed. Presence of multifocal (string-of-beads) extracoronary FMD was confirmed by 2 specialists. In these patients, coronary angiographic findings (excluding dissected segments) were reviewed and classified by 2 experienced angiographers for irregular stenosis, that is, stenosis with irregular borders in a focal or diffuse pattern with/without systolic accentuation; smooth stenosis, diffuse or focal; segmental dilatation/ectasia; and tortuosity. Optical coherence tomography was performed in a subset of patients. Of 32 patients with extracoronary FMD and suspected coronary involvement, 28 were women (88%), and their mean age was 59.4±9.9 years. Nineteen presented with myocardial infarction (13 caused by spontaneous coronary artery dissection), and 13 had stable symptoms. The observed coronary angiographic abnormalities included tortuosity in all cases (91% were moderate to severe), irregular stenosis in 59%, smooth stenosis in 19%, and segmental dilatation/ectasia in 56%. Fifteen patients had optical coherence tomography of the abnormal segments showing abnormalities, including multiple areas of patchy or diffuse intimal, medial or adventitial abnormalities with thickening/accumulation of varied reflectivities, macrophage infiltration, loss/duplication of elastic membranes, and cavitation., Conclusions: This is the first case series describing findings suggestive of angiographic and intracoronary manifestations of coronary FMD. Future studies should prospectively review these features in patients with extracoronary FMD., (© 2016 American Heart Association, Inc.)

Background: Fibromuscular dysplasia (FMD), a noninflammatory disease of medium-size arteries, may lead to stenosis, occlusion, dissection, and/or aneurysm. There has been little progress in understanding the epidemiology, pathogenesis, and outcomes since its first description in 1938., Methods and Results: Clinical features, presenting symptoms, and vascular events are reviewed for the first 447 patients enrolled in a national FMD registry from 9 US sites. Vascular beds were imaged selectively based on clinical presentation and local practice. The majority of patients were female (91%) with a mean age at diagnosis of 51.9 (SD 13.4 years; range, 5-83 years). Hypertension, headache, and pulsatile tinnitus were the most common presenting symptoms of the disease. Self-reported family history of stroke (53.5%), aneurysm (23.5%), and sudden death (19.8%) were common, but FMD in first- or second-degree relatives was reported only in 7.3%. FMD was identified in the renal artery in 294 patients, extracranial carotid arteries in 251 patients, and vertebral arteries in 82 patients. A past or presenting history of vascular events were common: 19.2% of patients had a transient ischemic attack or stroke, 19.7% had experienced arterial dissection(s), and 17% of patients had an aneurysm(s). The most frequent indications for therapy were hypertension, aneurysm, and dissection., Conclusions: In this registry, FMD occurred primarily in middle-aged women, although it presents across the lifespan. Cerebrovascular FMD occurred as frequently as renal FMD. Although a significant proportion of FMD patients may present with a serious vascular event, many present with nonspecific symptoms and a subsequent delay in diagnosis.