Part 1. Understanding the Embryology and Genetics of Cleft Lip and Palate

Abstract

Craniofacial birth defects are the fourth most common congenital anomaly in newborns. Cleft lip and cleft palate (CL/CP) are the most common and immediately recognizable craniofacial anomalies. Some are diagnosed prenatally on ultrasound; more often, they are first noted in the delivery room. The infant may have a cleft that is unilateral, bilateral, complete, or incomplete, and it may involve the lip only, the palate only, or both. Cleft lip and/or cleft palate are often isolated nonsyndromic occurrences; however, when associated with other abnormal physical findings, a recognizable syndrome may be present. Part 1 of this 2-part article describes the incidence of CL/CP. The embryology of the face, lip, and palate are reviewed to enhance the understanding of the timing, complexity, and factors that may influence the development of this lesion. The emerging genetic links, environmental influences, and potential teratogens that may interact to contribute to CL/CP are discussed. Part 2 of this series will provide clinicians with tools to perform a focused risk assessment and obtain a detailed family and pregnancy history to evaluate for known associated risk factors for CL/CP. The article provides a guide for a systematic physical examination of infants with CL/CP. Careful assessment for other midline defects or physical findings consistent with associated syndromes is also discussed. Pictorial examples of a variety of forms of CL/CP are provided to enhance understanding of the spectrum of this defect. Treatment and long-term complications of CL/CP are reviewed with an emphasis on family support, identifying educational resources, and counseling.

Épidémiologie des malformations associées aux fentes labiales et palatines à propos d’une étude rétrospective de 324 cas

“…Les fentes labiales et palatines comptent parmi les malformations congénitales les plus fréquentes [1]. En France, elles concernent entre 1,75 et 2,1 pour 1000 enfants nés vivants [2,3].…”

A veleszületett maxillofacialis deformitások klinikai aspektusai

“…Az ajakhasadékok gyakoribbak fi ú magzatokban, és a kombinált esetek aránya is 2:1 a fi úk javára, míg a szájpadhasadék lányoknál gyakoribb ugyanilyen arányban [16]. Lányoknál a szekunder szájpa-dot kialakító szájpadnyúlványok egyesülése egy héttel tovább tart, ami több lehetőséget ad a teratogén hatások kifejtésére [2,17,18,19,20]. Mindkét nemben az ajak vagy a primer szájpad bal oldala érintett gyakrabban [2].…”

“…A felső állkapocsnyúlvány kinövései a processus palatinalisok, avagy szájpadnyúlvá-nyok, amelyek a 6. héten jelennek meg, és hátrafelé és középvonal felé összenőve kialakítják a szekunder palatumot, ami előrefelé fuzionál a primer szájpaddal (a 6-12. hét között). A két szájpad közötti határ a foramen incisivum [1,5,6,17,19,22,21,23].…”

“…Az ajak-, illetve a szájpadhasadék eltérő embrioló-giai hátterű [5,19,22,24]. A hasadék nagysága és kialakulásának időpontja alapján különböző súlyosságú formák képződhetnek.…”

Maternal Diet Supplementation with Methyl Donors and Increased Parity Affect the Incidence of Craniofacial Defects in the Offspring of Twisted gastrulation Mutant Mice

“…Micrognathia (small jaw) represents a less severe BA1 defect (23). Orofacial clefting may also arise from defective BA1 development, because clefting of both palate (24,25) and lip (26,27) can derive from deficient growth of the maxillary component of BA1. Defects of midline formation, on the other hand, arise from the failure of proper patterning or signaling from the prechordal plate and ventral forebrain (28,29) and the frontonasal ectodermal zone, which direct the formation of the midline of the face (30)(31)(32).…”