Phenotypic characterization of class CIII malocclusion

OBJECTIVE: This study attempts to characterize CIII malocclusion phenotypes in order to identify distinct subgroups for which genetic susceptibility could be identified. METHODS: Sixty-three lateral cephalometric variables were measured from pre-treatment records of 292 CIII Caucasian adults. Principal component analysis (PCA) and cluster analysis (CA) were used to identify the most homogeneous groups of individuals representing distinct CIII phenotypes and thus reducing genetic heterogeneity. RESULTS: PCA resulted in 6 principal components that accounted for 81.17% of the variation. The first three components represented variation on mandibular and maxillary horizontal and vertical position and lower incisor angulation, respectively. The cluster model identified 5 distinct subphenotypes of CIII malocclusion. CONCLUSIONS: A spectrum of phenotypic definitions was obtained which may enhance the identification of human susceptibility genes underlying CIII malocclusion.