Soft tissue facial anthropometry in Down syndrome subjects

The three-dimensional coordinates of 50 selected soft tissue facial landmarks were digitized on 28 white Italian subjects with Down syndrome (17 male and 11 female subjects aged 12 to 45 years) and 429 healthy controls of comparable ages by an electromechanical instrument. From the landmarks, 16 facial dimensions were calculated. Data were compared with those collected in healthy individuals by computing z-scores. Overall, most variables were smaller in subjects with Down syndrome than in their normal controls selected for sex, age, and ethnicity (negative z-scores), even if not all of them reached statistical significance. Independently of sex, subjects with Down syndrome had faces that were significantly (P<0.05, paired Student t test) narrower (skull base and mandible), less deep (upper, middle, and lower face), and shorter (face and nose height) than the faces of normal subjects. Additionally, ear width and length were significantly reduced on both sides of the face. Only facial height was significantly different between sexes (P=0.023, unpaired Student t test), with a female z-score that was more than two times the relevant male value. The present investigation represents the first detailed quantitative analysis of the facial soft tissue characteristics of Italian white subjects with Down syndrome.