A study of the hereditary basis of cleft lip and cleft palate

Abstract

This study attempted to identify the incomplete manifestations of gene(s) producing cleft lip and/or cleft palate. An effort was made to determine how various oral-facial discrepancies, when considered as incomplete manifestations of clefting, might produce an obvious mode of inheritance of the clefting trait i n families with a history of cleft lip and/or cleft palate. Eleven families were studied, selection being made on the basis of the degree of relationship of the affected individuals to the proband. Oral and facial discrepancies including bifid uvula, mandibular lip pits, commissural lip pits, raphe of the upper lip, notching of the alveolus, asymmetrical nasal shape, congenitally missing and malformed maxillary central and lateral incisors, and excessive crowding of the teeth in the anterior segment of the maxillary arch were selected as possible incomplete manifestations of gene action. The results of this study demonstrated that when these manifestations were considered together with the cleft lip and/or cleft palate condition, no additional information on the manner of inheritance of the cleft lip and/or cleft palate trait was produced. Ocular and orbital measurements, which may also be used in determining possible mid-facial discrepancies, were compared between the relatives of families with a history of clefting and a control group of individuals ranging from four to 22 years of age. A total of 166 individuals were compared. Significant differences in the circumference-interorbital index, skeletal interorbital distance, and the canthal index were found. Since these significant differences in the ocular and orbital measurements could not be significantly related to the degree of relationship between affecteds (the test of heritability), they should be held with some reservation until a larger sample can be studied.