A quantitative study of the face in Down's syndrome.

The large number of persons with Down's syndrome among the group of physically and mentally retarded demands that continuing study be directed toward its causes and effects. Much conflicting data are reported in the literature concerning the facial and cranial effects of this syndrome. The cephalic proportions, in profile, of a group of male Caucasian trisomic Mongoloids were compared with the proportions of a control group of male Caucasians of similar age range. Using the areas of the midface, mandible, and endocranium obtained from cephlograms of the two groups, the following ratios were studied: (1) midfacial area/endocranial area (2) mandibular area/endocranial area, and (3) midfacial area/mandibular area. A significant degree of deficiency in midfacial area, mandibular area, and endocranial area was found in the Mongoloid group. In studying the facial proportions, we found that the Down's syndrome group's ratios were significantly smaller in all three areas. The magnitude of the deficiency in the Mongoloid midface, both in gross area and in relation to endocranial area, remained nearly constant with age. The ratio of midfacial area to mandibular area in Mongoloids was much more comparable to that of the normal group than the other two ratios studied. In both groups the ratio of the midfacial area to the mandibular area became smaller with age. The decrease was more rapid in the Down's syndrome group. The findings of this study imply that all areas of the face and skull are deficient in persons with Down's syndrome. The data point to the possibility that the characteristics of this syndrome and the deficiencies described are polygenic in origin. Also, contrary to the majority of reports in the literature, the mandible and the midface grow in approximately the same proportion in both study and control groups