Pathophysiology and Therapeutics of Thoracic Aortic Aneurysm in Marfan Syndrome

About 20% of individuals afflicted with thoracic aortic disease have single-gene mutations that predispose the vessel to aneurysm formation and/or acute aortic dissection often without associated syndromic features. One widely studied exception is Marfan syndrome (MFS) in which mutations in the extracellular protein fibrillin-1 cause additional abnormalities in the heart, eyes, and skeleton. Mouse models of MFS have been instrumental in delineating major cellular and molecular determinants of thoracic aortic disease. In spite of research efforts, translating experimental findings from MFS mice into effective drug therapies for MFS patients remains an unfulfilled promise. Here, we describe a series of studies that have implicated endothelial dysfunction and improper angiotensin II and TGFβ signaling in driving thoracic aortic disease in MFS mice. We also discuss how these investigations have influenced the way we conceptualized possible new therapies to slow down or even halt aneurysm progression in this relatively common connective tissue disorder.

How to Distinguish Marfan Syndrome from Marfanoid Habitus in a Physical Examination—Comparison of External Features in Patients with Marfan Syndrome and Marfanoid Habitus

Marfan Syndrome (MFS) is a systemic disorder caused by mutations in fibrillin-1. The most common cause of mortality in MFS is dissection and rupture of the aorta. Due to a highly variable and age-dependent clinical spectrum, the diagnosis of MFS still remains sophisticated. The aim of the study was to determine if there exist phenotypic features that can play the role of “red flags” in cases of MFS suspicion. The study population included 306 patients (199 children and 107 adults) who were referred to the Department of Pediatric Cardiology due to suspicion of MFS. All patients underwent complete clinical evaluation in order to confirm the diagnosis of MFS according to the modified Ghent criteria. MFS was diagnosed in 109 patients and marfanoid habitus in 168 patients. The study excluded 29 patients with other hereditary thoracic aneurysm syndromes. Comparative analysis between patients with Marfan syndrome and marfanoid habitus was performed. Symptoms with high prevalence and high positive likelihood ratio were identified (pectus carinatum, reduced elbow extension, hindfoot deformity, gothic palate, downslanting palpebral fissures, lens subluxation, myopia ≥ 3 dioptres remarkably high stature). The differentiation between patients with MFS and marfanoid body habitus is not possible by only assessing external body features; however, “red flags” could be helpful in the screening phase.

Aortic Root Dilatation in Children and Adolescents At Al-Hawary General Hospital, & National Benghazi Cardiac Center -Libya

Isolated dilatation of the aortic root and/or ascending aorta is a rare but well-known cardiovascular manifestation, can be caused by a variety of congenital or acquired conditions; that lead to the weakening of the aortic wall. The study aimed to detect the cause and the rate of the aortic root dilatation in children and adolescents, and to assess the effect of the Beta-adrenergic blockers in preventing further dilatation in the aortic root. A case series study was perform with five years of follow-up at Al-Hawary General Hospital, National Benghazi Cardiac Center. A total of 91 patients were seen with ascending aortic dilatation and/or root dilatation during the period from 6/2016 - 6/2021 included in the study diagnosed by clinical examination, chest x-ray, and echocardiogram. The diagnosis in 34/91(37%) was Tetralogy of fallout (TOF) and truncus arteriosus, 57/91 (63%) was dilated aortic root, 25/57 (44%) bicuspid aortic valve (BAV), 22/57 (38.5%) Marfan syndrome, 4/57(7%) Noonan syndrome, 2/57(3.5%) Turner syndrome, 3/57(5%) Ehlers-Danlos syndrome, 1/57(2%) idiopathic. Follow-up results of three months – five years: 57/91 patients with aortic root dilatation were followed up, none of the Marfan syndrome and Ehlers-Danlos syndrome patients who received beta-blockers had shown progression in the dilatation of the aortic root, and all patients who had bicuspid aortic valve did not show any progression in the dilatation without using medication. Conclusions: Dilated aortic root is a common finding in Marfan syndrome, bicuspid aortic root, and Ehlers-Danlos syndrome, and its progress could be decreased by using beta-adrenergic blockers in rapidly progressing dilation.

Multi-Omics Profiling in Marfan Syndrome: Further Insights into the Molecular Mechanisms Involved in Aortic Disease

Thoracic aortic aneurysm is a potentially life-threatening disease with a strong genetic contribution. Despite identification of multiple genes involved in aneurysm formation, little is known about the specific underlying mechanisms that drive the pathological changes in the aortic wall. The aim of our study was to unravel the molecular mechanisms underlying aneurysm formation in Marfan syndrome (MFS). We collected aortic wall samples from FBN1 variant-positive MFS patients (n = 6) and healthy donor hearts (n = 5). Messenger RNA (mRNA) expression levels were measured by RNA sequencing and compared between MFS patients and controls, and between haploinsufficient (HI) and dominant negative (DN) FBN1 variants. Immunohistochemical staining, proteomics and cellular respiration experiments were used to confirm our findings. FBN1 mRNA expression levels were highly variable in MFS patients and did not significantly differ from controls. Moreover, we did not identify a distinctive TGF-β gene expression signature in MFS patients. On the contrary, differential gene and protein expression analysis, as well as vascular smooth muscle cell respiration measurements, pointed toward inflammation and mitochondrial dysfunction. Our findings confirm that inflammatory and mitochondrial pathways play important roles in the pathophysiological processes underlying MFS-related aortic disease, providing new therapeutic options.