Craniofacial shape in patients with beta thalassaemia: a geometric morphometric analysis

Abstract

The shape of the craniofacial complex of patients with beta thalassaemia was evaluated using geometric morphometrics on lateral cephalometric radiographs and was compared with matched controls. The beta thalassaemia group consisted of 40 patients (16 females, 24 males, mean age 33.4). Each patient was matched by age and gender to two controls (32 females, 48 males, mean age 33.1). The 120 lateral cephalometric radiographs were digitized and traced with 15 curves, 10 landmarks and 117 sliding semi-landmarks. These landmarks were subjected to Procrustes superimposition and principal component analysis in order to describe shape variability of the cranial base, maxilla and mandible, as well as of the entire craniofacial complex for each sex. The first 4 principal components accounted for 50% of the total sample’s variability. The beta thalassaemia group was significantly different in overall shape to the control group for both sexes. Similar findings were noted for the maxilla, the mandible and the cranial base. The main differences were related to smaller mandibular body for the thalassaemia group, midface protrusion and decrease in posterior face height. The shape of the craniofacial complex in these patients is prone to be more convex and hyperdivergent.