Marfan syndrome type II: there is more to Marfan syndrome than fibrillin 1

Abstract

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.