Marfan syndrome is a well-described autosomal dominant syndrome with widely 
variable clinical manifestations. Cardiovascular complications include mitral 
valve prolapse with or without associated mitral valve insufficiency, aortic 
root dilatation, and most importantly the occasional development of aortic 
aneurysms or rupture. Given the inconsistent phenotype along with the 
potentially life-threatening implications, clinicians are increasingly turning 
to genetic testing for definitive diagnostic confirmation. It has been well 
established that mutations in the FBN1 gene encoding the structural protein 
Fibrillin 1 is the molecular etiology of Marfan syndrome. However, there are 
numerous patients who meet the Ghent clinical diagnostic criteria for Marfan 
syndrome who do not have identifiable FBN1 mutations. Recently, mutations in 
TGFBR1 and TGFBR2 (transforming growth factor beta receptors 1 and 2, 
respectively) have been shown to result in Loeys-Dietz syndrome, a connective 
tissue disorder with significant phenotypic overlap with Marfan syndrome. 
Individuals with this Marfanoid disorder lack the ocular findings of Marfan 
syndrome and often have dysmorphic features such as unusual facies, cleft 
palate, and contractures. In addition, Loeys-Dietz syndrome patients often 
present in childhood with significant cardiovascular problems. This article 
serves to report an illustrative case of Loeys-Dietz syndrome and reviews the 
phenotypic consequences of FBN1 and TGFBR1 and TGFBR2 gene mutations.