Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder with pleiotropic manifestations in the ocular, skeletal and cardiovascular systems. Morbidity and mortality are mostly determined by aortic root aneurysm dissection and rupture. Although mutations in FBN1, the gene coding for the extracellular matrix protein fibrillin-1, are the well-established genetic cause of this condition, there is a very poor correlation between the nature or location of the causal FBN1 mutation and the phenotypical outcome. Indeed, wide intra- and interfamilial phenotypical variability is observed. So, even with an identical primary mutation in all family members, the clinical spectrum varies widely, from completely asymptomatic to sudden death due to aortic dissection at a young age. The precise mechanisms underlying this variability remain largely elusive. Consequently, a better understanding of the functional effects of the primary mutation is highly needed and the identification of genetic variation that modifies these effects is becoming increasingly important. In this project, we have carefully selected different innovative strategies to discover mother nature's own modifying capabilities with respect to Marfan syndrome aortopathy.