While evidence of mild medial degeneration in WVG-stained slides was similar between the AAE case and the control animals, the reduced FBN1 immunofluorescent signal in the ascending aorta was unique to the AAE case, suggesting that the pathogenesis of this dog's aortic dilation had overlapping features with Marfan syndrome in humans. This evidence concerns the gene FBN1 and acquired angioedema.