Loeys-Dietz syndrome (LDS) is a recently-described autosomal dominant syndrome which has features similar to the Marfan syndrome (MFS). It is characterized by hypertelorism, bifid/broad uvulas, and most importantly, aortic aneurysms. These aneurysms occur most frequently in the root of the aorta (the main artery that brings blood from the heart to the rest of the body). In Loeys-Dietz syndrome, the aortic aneurysms are prone to rupture at a smaller size than in other aortic aneurysm syndromes, putting individuals with Loeys-Dietz at risk for rupture if the aneurysm is not identified and treated early. It is caused by mutations in the transforming growth factor beta receptors TGFBR1 or TGFBR2.

At present there is no known cure for LDS. It is a genetic condition which requires frequent monitoring for aneurysm formation not only in the aorta, but throughout the arterial tree from the head to the pelvis. Importantly, individuals with LDS do very well with cardiac and vasculature surgery when it is needed.

LDS has several similarities to various connective tissue disorders including Marfan syndrome, Ehlers-Danlos syndrome and Shprintzen-Goldberg syndrome. Many individuals are first diagnosed with one of these syndromes prior to an LDS diagnosis.

Since increasing dilation of the aortic root is of such concern in some connective tissue disorders, there is a large clinical trial currently sponsored by the National Institute of Health for the use of Losartan in individuals with MFS. Because of the overlap of LDS with MFS, individuals should consult with their cardiologist to discuss use of Losartan in LDS.

A friend in Australia sent me the following description (from her geneticist) as notes on the two types of LDS. But it should be noted that both TGFBR1 and TGFBR2 mutations can cause either Type I or Type II LDS. Thus Type I LDS is not just caused by TGFBR1 mutations nor is Type II LDS only associated with TGFBR2 mutations.