Soft tissue facial areas and volumes in subjects with Down syndrome

The objective of this study was to supply quantitative information about the facial soft-tissues of a group of subjects with Down syndrome. The three-dimensional coordinates of 28 soft-tissue facial landmarks were obtained by an electromechanic digitizer in 17 male and 11 female subjects with Down syndrome aged 12-45 years, and in 429 healthy individuals of the same age, ethnicity, and sex. From the landmarks, facial areas (eyes, ears, nose, and lips) and volumes (nose and lips) were calculated according to a geometrical model of face. Data were compared to those collected in the normal subjects by computing z-scores. Male and female z-scores were not significantly different. Most of the facial volumes were significantly (Student's t, P < 0.05) smaller in subjects with Down syndrome than in their normal controls. Ear areas were significantly reduced (mean z-scores in males -2.07 right, -1.9 left; in females -2.11 right, -2.21 left), as well as nasal surface area (mean z-score -1.53 in males, -2.45 in females). In women, age and some z-scores were significantly correlated (P < 0.05): upper lip volume (r = 0.714), left and right eye area (r = 0.635, right; 0.604, left), nasal area (r = 0.603): with increasing age, the negative values of the z-scores approached the 0 value of the reference population. In the pooled sample, age and the z-score of the total lip area were significantly correlated (r = 0.423): increasing age corresponded to a larger z-score value. The method allowed a simple, low cost, fast, and noninvasive examination of the subjects, and provided a quantitative assessment of the deviation from the norm.