Dr. Hal Dietz discovered fibrillin-1 as the underlying genetic cause of Marfan syndrome (MFS) in 1991. MFS is a potentially fatal connective tissue disorder, which leads to enlargement of the aorta. Dr. Dietz’s devotion to patients, both in the clinic and in the laboratory, has continued full force, and he has since helped to discover the genes underlying other conditions that cause aortic aneurysms, including Loeys-Dietz syndrome. In addition, his work has shown that the pathogenesis of MFS is more complex but at the same time more amenable to pharmacotherapy, leading to the first clinical trial in MFS.