Quantitative approach to identifying abnormal variation in the human face exemplified by a study of 278 individuals with five craniofacial syndromes.

We have two objectives in this study: to demonstrate the utility of two summary anthropometric measures for quantifying craniofacial variation and to explore some of their potential uses by physicians and clinical morphologists in general. The Craniofacial Variability Index (CVI) is a summary anthropometric measure of facial "harmony." The mean z-score, based on craniofacial anthropometry, is a measure of overall facial size. Both add an objective component to the assessment of individual facial variation and allow us to place the individual along a scale of continuous variation with predetermined limits of "normality" based on a reference or control series. Our results suggest that these summary measures coincide well with clinical assessments of abnormality in 278 individuals representing five distinct syndromes (Brachmann-de Lange, Prader-Willi, Rubinstein-Taybi, Smith-Magenis, and Sotos), each of which has an associated craniofacial component. Although craniofacial variation is continuous and the normal and syndromic populations overlap to varying degrees, the syndromic cases can be characterized in a variety of ways by using CVI as a measure of facial harmony and Mean-Z as an indicator of overall facial size. Thus, these two-objective measures offer a novel and efficient means of assessing craniofacial variation, whether they are used as tools in the clinical evaluation of subjects or as a means of exploring the nature of craniofacial variation within or between syndromes.