SMAD3 and Andersen-Tawil syndrome: Comparable to several other conditions known as TGF-β vasculopathies and presenting with arterial aneurysms, such as MFS [21], the other LDS types [9] and ATS [5], TGFB2 loss-of-function resulted in a activation in TGF-β signaling pathway [22],[23], as shown by the increase of phosphorylated SMAD2 and SMAD3 (SMAD2/3) levels in aortic lesions from TGFB2+/− patients and Tgfb2+/− mice, as well as by elevated ligand levels of either TGF-β1 [16] or TGF-β2 [17].