An Epidemiologic Investigation of Factors Related to the Extent of Facial Clefts. I. Sex of Patient

Abstract

Previous investigations have indicated that the incidence of facial clefts is not equal for males and females. Differences between the two sexes have been noted which appear dependent on the type of cleft (isolated cleft lip, cleft lip in combination with cleft palate, or isolated cleft palate) (2, 3). Furthermore, it must be noted that within the three qualitative cleft types there are quantitative gradations. For example, not all clefts of the lip are complete and not all palatal clefts involve the entire hard and soft palate. Indeed, it is possible to have an extremely large number of quantitative assessments of the facial cleft process. Little is known about the sex distribution for the severity spectrum of isolated cleft lip and cleft lip—cleft palate combinations. However, there are data concerning this aspect for isolated cleft palate. Knox and Braith-waite (5) divided palatal clefts into two groups: a) complete post— alveolar clefts, and b) submucous clefts of soft palate and minor hard palate. Their results were based on 104 cases of isolated cleft palate and indicate that, for all clefts of the palate, without regard to extent, the female-to-male ratio was 1.5:1. When these clefts were analyzed according to the two anatomic divisions, the sex ratios were found to be 2.1 :1 and 0.94:1 respectively. The reversal in sex ratio for the less severe clefts is quite evident. Two other studies yield data which lend themselves to similar comparisons. Fogh-Andersen (1) divided palatal cleft into two groups: large and small clefts. The so-called large clefts involved both hard and soft palates, while the small-cleft group involved the soft palate