Spontaneous coronary artery dissection is infrequent in individuals with heritable thoracic aortic disease despite partially shared genetic susceptibility.

Spontaneous coronary artery dissection (SCAD) is a potential precipitant of myocardial infarction and sudden death for which the etiology is poorly understood. Mendelian vascular and connective tissue disorders underlying thoracic aortic disease (TAD), have been reported in ~5% of individuals with SCAD. We therefore hypothesized that patients with TAD are at elevated risk for SCAD. We queried registries enrolling patients with TAD to define the incidence of SCAD. Of 7568 individuals enrolled, 11 (0.15%) were found to have SCAD. Of the sequenced cases (9/11), pathogenic variants were identified (N = 9), including COL3A1 (N = 3), FBN1 (N = 2), TGFBR2 (N = 2), TGFBR1 (N = 1), and PRKG1 (N = 1). Individuals with SCAD had an increased frequency of iliac artery dissection (25.0% vs. 5.1%, p = 0.047). The prevalence of SCAD among individuals with TAD is low. The identification of pathogenic variants in genes previously described in individuals with SCAD, particularly those underlying vascular Ehlers-Danlos, Marfan syndrome, and Loeys-Dietz syndrome, is consistent with prior reports from clinical SCAD series. Further research is needed to identify specific genetic influences on SCAD risk.

A Novel Recurrent COL5A1 Genetic Variant Is Associated With a Dysplasia-Associated Arterial Disease Exhibiting Dissections and Fibromuscular Dysplasia.

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.

The Association of Intracranial Aneurysms in Women with Renal Artery Aneurysms.

BACKGROUND: Renal artery aneurysms (RAAs) may reflect a systemic dysplastic arteriopathy, independent of a recognized connective tissue disease. It is hypothesized that RAAs are associated with an increased risk of intracranial aneurysms (IcAs). The objective of this study was to better define the association of IcAs in women with RAAs. METHODS: Women aged 20 to 60 years who presented with RAAs at the University of Michigan from 2001 to 2016 were included in the study. Their clinical status and radiologic images were retrospectively reviewed, with particular attention directed to the prevalence of IcAs. Phenotypic characteristics predictive of associated cerebrovascular lesions were assessed using various statistical analyses, including binomial logistic regression. RESULTS: Among 83 women with RAAs, the average age at the time of RAA detection was 45.3 ± 9.9 years (range, 20-60 years). Hypertension affected 56 (67.5%) patients and poorly controlled hypertension prompted imaging for suspected renal arterial disease in 12 (14.5%) patients. Multifocal fibromuscular dysplasia occurred in 12 (14.8%) of patients, and unifocal stenosis affected 7 (8.4%) patients. Imaging of the intracranial vasculature (n = 31) documented 12 aneurysms in 9 women, with the cavernous internal carotid artery being the most commonly affected artery. Among the study's patients, 20 (24.1%) had an "at-risk disorder for IcA formation," although the frequency of relevant "at-risk disorders" in those with and without IcAs was not statistically different (P = 0.21). Rupture risk defined by PHASES score was less than 1% for 10 IcAs, but 2 IcAs carried a 2.4% and 7.2% rupture risk, respectively, over a 5-year time period. Surgical management was pursued in 6 (50%) of the study's IcAs. CONCLUSIONS: Coexisting RAAs and IcAs may reflect a systemic arteriopathy. IcAs appear to occur with greater frequency in women with RAAs than the general population. This observation warrants prospective investigation as to the clinical appropriateness and relevance of cerebrovascular imaging in women with RAAs. Furthermore, this study's findings prompt further investigation of the underlying pathogenesis of what appears to be a broader and more complex arterial disease than previously recognized.

Polyethylene glycol modified, cross-linked starch-coated iron oxide nanoparticles for enhanced magnetic tumor targeting.

While successful magnetic tumor targeting of iron oxide nanoparticles has been achieved in a number of models, the rapid blood clearance of magnetically suitable particles by the reticuloendothelial system (RES) limits their availability for targeting. This work aimed to develop a long-circulating magnetic iron oxide nanoparticle (MNP) platform capable of sustained tumor exposure via the circulation and, thus, potentially enhanced magnetic tumor targeting. Aminated, cross-linked starch (DN) and aminosilane (A) coated MNPs were successfully modified with 5 kDa (A5, D5) or 20 kDa (A20, D20) polyethylene glycol (PEG) chains using simple N-Hydroxysuccinimide (NHS) chemistry and characterized. Identical PEG-weight analogues between platforms (A5 & D5, A20 & D20) were similar in size (140-190 nm) and relative PEG labeling (1.5% of surface amines - A5/D5, 0.4% - A20/D20), with all PEG-MNPs possessing magnetization properties suitable for magnetic targeting. Candidate PEG-MNPs were studied in RES simulations in vitro to predict long-circulating character. D5 and D20 performed best showing sustained size stability in cell culture medium at 37 °C and 7 (D20) to 10 (D5) fold less uptake in RAW264.7 macrophages when compared to previously targeted, unmodified starch MNPs (D). Observations in vitro were validated in vivo, with D5 (7.29 h) and D20 (11.75 h) showing much longer half-lives than D (0.12 h). Improved plasma stability enhanced tumor MNP exposure 100 (D5) to 150 (D20) fold as measured by plasma AUC(0-∞). Sustained tumor exposure over 24 h was visually confirmed in a 9L-glioma rat model (12 mg Fe/kg) using magnetic resonance imaging (MRI). Findings indicate that a polyethylene glycol modified, cross-linked starch-coated MNP is a promising platform for enhanced magnetic tumor targeting, warranting further study in tumor models.