Asymmetry of the parental craniofacial skeleton in orofacial clefting

Objective: To evaluate size-related and shape-related craniofacial skeletal asymmetries in the parents of children with orofacial clefting (OFC).

Design: Retrospective PA cephalometric study.

Setting: Glasgow/Dundee, Scotland. Subjects: Ninety-two parental volunteers from a completely ascertained sample of 286 children born with OFC between 1980–1984 in the West of Scotland.

Interventions: None. 

Main outcome measures: A conventional cephalometric asymmetry analysis (CCAA) evaluated size-related right:left asymmetry comprising eight linear distance, nine angular, and three mid-facial area measurements. The right and left landmark configurations were uniformly scaled using Procrustes superimposition and Euclidean Distance Matrix Analysis (EDMA) evaluated shape-related right-left asymmetry 

Results: The three linear distances, nine angles and two areas differed between the right and left sides of the craniofacial complex (P <0.05) indicate size asymmetry characterized by a wider left side of the face and a shorter vertical dimension on the right side (directional asymmetry). EDMA detected shape asymmetry [T statistic = 2.671 (P = 0.10)]. Forty per cent of the EDMA ratios were clinically importantly larger or smaller on the left and right sides respectively, involving landmarks anatomically and morphogenetically important in OFC. 

Conclusion: Size and shape directional asymmetries characterize the parental craniofacial skeleton in OFC. This heritable directional craniofacial skeletal asymmetry could be of relevance in the left-sided predilection of OFC.