Cleft Lip and Cleft Palate

Abstract

Clefts of the primary and secondary palate are among the most 'important congenital malformations, judging by the burden of expense and unhappiness they impose on society. Yet evidence of the embryological mechanisms by which they occur is scattered, scanty, and conflicting. In view of this fact, a small group of workers, directly involved in research on palate formation and its failure, met in Denver 22-23 May 1967 to evaluate the current status of knowledge in the field. Two days were spent in comparing data, slides and opinions, and although no intellectual breakthroughs were achieved, or indeed anticipated, the resulting consolidation of knowledge may stimulate and orient further efforts in this area. In the following account, references will not be given to published work, but unpublished observations will be acknowledged by including the participant's name in parentheses.The primary palate (lip and gum) is formed from the maxillary and nasal processes at an early stage of development when many important organogenetic processes are rapidly occurring. There are, as one might expect, differences among species in morphology of the early face. For instance, in the rat and mouse the central part of the upper lip is formed by the maxillary processes, which meet each other in the midline. In man it is formed by the medial nasal processes. Rat and mouse differ in the relative size and position of medial and lateral nasal processes. Yet the mouse, rat, and human embryos are remarkably similar in size when the face is forming, and basically the process of face formation appears to be the same in the mammalian species studied.Evidence from amphibia and chick shows that the nasal placodes are induced in the presumptive face epithelium primarily by the parts of the forebrain that will become the olfactory lobes. The mesenchyme of the swellings, or processes, that form the early face are derived from neural crest cells 22 DECEMBER 1967

Collagen XI sequence variations in nonsyndromic cleft palate, Robin sequence and micrognathia

“…This hypothesis is supported by the findings that nonsyndromic oral clefting is multifactorial and involves both genetic and environmental factors 1,2 and that the concordance for nonsyndromic cleft palate in monozygotic twins is only 23.5%. 29 Even though disease-associated alterations in the three candidate genes were not found in the majority of patients, we can conclude that sequence variations in these genes may cause or predispose to nonsyndromic Robin sequence, cleft palate, and micrognathia in some cases.…”

Development of the upper lip: Morphogenetic and molecular mechanisms

“…Another common form of orofacial clefting is cleft palate (CP), which appears as a gap in the secondary palate while the upper lip appears intact. Epidemiological and embryological studies suggest that CLP and CP have distinct etiology, although these two phenotypes sometimes appear in the same family (Fraser, 1970;Vanderas, 1987;Gorlin et al, 2001). Both CLP and CP have syndromic and nonsyndromic forms with the syndromic clefting often caused by single gene mutations, chromosomal abnormalities, or teratogenic exposure (Gorlin et al, 2001;Wyszynski, 2002).…”

Some Uses of Models of Quantitative Genetic Selection in Social Science

“…The model further specifies what the incidence should be in relatives of varying degree. It predicts cleft palate risk in relatives of those affected quite closely (Fraser, 1970). Cloninger et al (1975b) proposed a threshold model for the prevalence of sociopathy and hysteria in humans.…”