FACIAL FORM AS A SUBCLINICAL PHENOTYPE OF NONSYNDROMIC OROFACIAL CLEFTING: AN ANTHROPOMETRIC ANALYSIS

Orofacial clefting (OFC) is the most common craniofacial anomaly, seen in every 1 in 500 to 2500 births worldwide. It has been identified that 60 to 70% of OFC are non-syndromic (NS) and are not associated with any single genetic marker. However, high recurrence rates of NSOFC have been identified in families. The recurrence risk is predicted on rather empirical data owing to poor gene mapping and poor correlation between genotype and phenotype of this anomaly. Considering the fact that OFC presents with significant etiologic heterogeneity and phenotypic diversity, subclinical manifestations need to be identified to complete the OFC phenotypic spectrum. This will improve correlation between genotype and phenotype and thus improve recurrence risk estimation. A large body of evidence suggests that subtle changes in craniofacial morphology may be a subclinical marker for cleft susceptibility. A vast majority of this evidence is based on cephalometric data with far fewer studies examining soft tissue features of the face. The purpose of the present study is to compare craniofacial characteristics of unaffected biological parents of NS OFC offspring with controls derived from the same population using direct anthropometry.\ud The study sample consisted of 67 male and 76 female unaffected parents of both NS Cleft lip and Cleft lip/palate children. Control sample comprised of 37 normal males and 59 normal females of the same race and ethnicity. Craniofacial measurements of both study and control\ud population were collected using direct anthropometry as was described by Farkas (1994) and Kolar & Salter (1997) and were subjected to stepwise discriminant functional analysis (DFA). DFA is similar to logistic regression; used to classify population into groups based on covariate variables. In this study discriminant models with high statistical significance (P‹0.001) were derived in males and females that could clearly distinguish unaffected parents from controls based on direct anthropometrically measured craniofacial characteristics. The study showed that salient discriminating features are localized to specific regions of the face in a partly gender-specific manner. The study showed that a model derived using a small subset of direct anthropometrically measured craniofacial features can be used to discriminate unaffected parents from the controls