The face in Marfan syndrome : a 3D quantitative approach for a better definition of dysmorphic features

Introduction. Marfan syndrome (MFS) is a rare hereditable disorder of connective tissue caused by mutations in the FBN1 (fibrillin-1) gene. Timely diagnosis of MFS is essential to prevent life-threatening cardiovascular complications; nevertheless it may be difficult, due to the phenotype variability of the syndrome. A clear quantitative definition of facial abnormalities associated with MFS is not available. The study aimed to better define the facial phenotype associated with MFS and verify the usefulness of a 3D noninvasive quantitative approach for its early recognition. Materials and Methods. 3D facial images of 61 Italian subjects with MFS, aged 16-64 years (21 males, 3815 years; 40 females, 4113 years) were obtained by stereophotogrammetry. From the coordinates of 17 soft-tissue facial landmarks, linear distances and angles were computed; z score values were calculated comparing patients with healthy reference subjects (400 males, 379 females), matched for sex and age. Statistical comparisons were performed by Student’s t test. Results. All subjects with MFS showed a greater facial divergence (p<0.001; mean z score +1.9) and a reduced facial height index (p<0.001; mean z score -1.9), being both values influenced by a shorter mandibular ramus (p<0.001; mean z score -1.9) and a mild but significant increase of facial height (p<0.001; mean z score +1.2). Palpebral down-slanting was found in 85% of MFS subjects. Sex differences were not observed. Conclusions. Quantitative abnormalities pointed out in the study enrich information about the facial dysmorphysm in MFS and confirm the usefulness of its evaluation for the early recognition of the disease.