FBN1 and Loeys-Dietz syndrome: TGF-β1 has been implicated in the pathophysiology of aortic aneurysms in patients with and without MFS, via both direct genetic mutations in the TGF-β pathway (Loeys-Dietz Syndrome) and as a consequence of FBN1 mutations (MFS) leading to dysregulated TGF-β1 levels in the pericellular environment and excessive TGF-β1 signaling through ALK receptors.