Incidence of Cleft Lip, Cleft Palate, and Cleft Lip and Palate Among Races: A Review

Abstract

A review of the literature pertaining to the incidence of cleft lip, cleft palate, and cleft lip and palate in different races is presented. The studies have been evaluated according to the method used to record the incidence rate. Half of the studies include in their base population livebirths, stillbirths, and abortions, or livebirths and stillbirths to record the incidence rate. In addition, in most of the studies, clefts with associated malformations and possible syndromes are included in the reported incidence. There is evidence, however, to suggest that the risk of developing clefts in stillbirths and abortions is three times as frequent as in livebirths and that clefts with associated malformations behave differently epidemiologically from clefts without associated mal-formations. It is suggested, therefore, that the incidence of cleft lip, cleft palate, and cleft lip and palate should be studied separately for each group, namely for livebirths, stillbirths, and abortions and should be reported separately for clefts without associated malformations, clefts with associated malformations, and syndromes. More research is needed to study the risk of developing clefts among the various groups that exhibit different epidemiologic behavior for each race. Many epidemiologic studies have been conducted on the incidence of cleft lip, cleft palate, and cleft lip and palate in the United States and in other countries. Their results show a wide variation in the risk of developing clefts within and among races. The majority of the studies include in the base population groups of subjects that differ in risk of developing orofacial clefts. In addition, in most of the studies, the reported incidence includes clefts with associated malfor-mations and possible syndromes that behave differently epidemiologically from clefts without associated malformations. The purpose of this paper is to review the epidemiologic studies conducted in different races on the incidence of cleft lip, cleft palate, and cleft lip and palate and to provide a critical evaluation of the methods used to record the incidence rate. REVIEW OF LITERATURE