Absence of cardiovascular manifestations in a haploinsufficient Tgfbr1 mouse model

Loeys-Dietz syndrome (LDS) is an autosomal dominant arterial aneurysm disease belonging to the spectrum of transforming growth factor β (TGFβ)-associated vasculopathies. In its most typical form it is characterized by the presence of hypertelorism, bifid uvula/cleft palate and aortic aneurysm and/or arterial tortuosity. LDS is caused by heterozygous loss of function mutations in the genes encoding TGFβ receptor 1 and 2 (TGFBR1 and -2), which lead to a paradoxical increase in TGFβ signaling. To address this apparent paradox and to gain more insight into the pathophysiology of aneurysmal disease, we characterized a new Tgfbr1 mouse model carrying a p.Y378*nonsense mutation. Study of the natural history in this model showed that homozygous mutant mice die during embryonic development due to defective vascularization. Heterozygous mutant mice aged 6 and 12 months were morphologically and (immuno)histochemically indistinguishable from wild-type mice. We show that the mutant allele is degraded by nonsense mediated mRNA decay, expected to result in haploinsufficiency of the mutant allele. Since this haploinsufficiency model does not result in cardiovascular malformations, it does not allow further study of the process of aneurysm formation. In addition to providing a comprehensive method for cardiovascular phenotyping in mice, the results of this study confirm that haploinsuffciency is not the underlying genetic mechanism in human LDS

Pregnancy outcome in thoracic aortic disease data from the Registry of Pregnancy and Cardiac disease

Background: Cardiovascular disease is the leading cause of death during pregnancy with thoracic aortic dissection being one of the main causes. Thoracic aortic disease is commonly related to hereditary disorders and congenital heart malformations such as bicuspid aortic valve (BAV). Pregnancy is considered a high risk period in women with underlying aortopathy. Methods: The ESC EORP Registry Of Pregnancy And Cardiac disease (ROPAC) is a prospective global registry that enrolled 5739 women with pre-existing cardiac disease. With this analysis, we aim to study the maternal and fetal outcome of pregnancy in women with thoracic aortic disease. Results: Thoracic aortic disease was reported in 189 women (3.3%). Half of them were patients with Marfan syndrome (MFS), 26% had a BAV, 8% Turner syndrome, 2% vascular Ehlers-Danlos syndrome and 11% had no underlying genetic defect or associated congenital heart defect. Aortic dilatation was reported in 58% of patients and 6% had a history of aortic dissection. Four patients, of whom three were patients with MFS, had an acute aortic dissection (three type A and one type B aortic dissection) without maternal or fetal mortality. No complications occurred in women with a history of aortic dissection. There was no significant difference in median fetal birth weight if treated with a beta-blocker or not (2960 g (2358-3390 g) vs 3270 g (2750-3570 g), p value 0.25). Conclusion: This ancillary analysis provides the largest prospective data review on pregnancy risk for patients with thoracic aortic disease. Overall pregnancy outcomes in women with thoracic aortic disease followed according to current guidelines are good

Intrinsic cardiomyopathy in Marfan syndrome: results from in- and ex-vivo studies of the Fbn1C1039G/+ model and longitudinal findings in humans

BACKGROUND: Mild intrinsic cardiomyopathy in patients with Marfan syndrome (MFS) has consistently been evidenced by independent research groups. So far, little is known about the long-term evolution and pathophysiology of this finding. METHODS:To gain more insights into the pathophysiology of MFS-related cardiomyopathy, we performed in-vivo and ex-vivo studies of 11 Fbn1(C1039G/+) mice and 9 wild-type (WT) littermates. Serial ultrasound findings obtained in mice were correlated to the human phenotype. We therefore reassessed left ventricular (LV) function parameters over a 6-y follow-up period in 19 previously reported MFS patients, in whom we documented mild LV dysfunction. RESULTS: Fbn1(C1039G/+) mice demonstrated LV contractile dys-function. Subsequent ex-vivo studies of the myocardium of adult mutant mice revealed upregulation of TGF beta-related pathways and consistent abnormalities of the microfibrillar network, implicating a role for microfibrils in the mechanical properties of the myocardium. Echocardiographic parameters did not indicate clinical significant deterioration of LV function during follow-up in our patient cohort. CONCLUSION: In analogy with what is observed in the majority of MFS patients, the Fbn1(C1039G/+) mouse model demonstrates mild intrinsic LV dysfunction. Both extracellular matrix and molecular alterations are implicated in MFS-related cardiomyopathy. This model may now enable us to study therapeutic interventions on the myocardium in MFS