Cleft lip and cleft palate
Cleft lip and cleft palate—an opening in the lip or palate—may occur separately or in combination. These deformities originate in the 2nd month of pregnancy, when the front and sides of the face and the palatine shelves fuse imperfectly. Cleft deformities usually occur unilaterally or bilaterally, rarely midline. Only the lip may be involved, or the defect may extend into the upper jaw or nasal cavity.
Cleft lip and cleft palate occur in twice as many males as females; isolated cleft palate is more common in females.
Cleft lip or palate can occur as part of another chromosomal or Mendelian abnormality (more than 150 have been identified); however, exposure to teratogens during fetal development or a combination of genetic and environmental factors may also produce these defects.
Cleft lip with or without cleft palate occurs in about 1 in 1,000 births among Whites; the incidence is higher among Asians (1.7 in 1,000) and Native Americans (more than 3.6 in 1,000) but lower among Blacks (1 in 2,500). A positive family history is a risk factor for cleft defects.
Signs and symptoms
Congenital defects of the face usually occur in the upper lip. They range from a simple notch to a complete cleft from the lip edge through the floor of the nostril, on either side of the midline, but rarely along the midline itself.
A cleft palate may be partial or complete. A complete cleft includes the soft palate, the bones of the maxilla, and the alveolus on one or both sides of the premaxilla. A double cleft runs from the soft palate forward to either side of the nose, separating the maxilla and premaxilla into freely moving segments. In Pierre Robin syndrome, the tongue is displaced due to micrognathia. The tongue prevents the palate from fusing. Glossoptosis coexists with cleft palate.
Isolated cleft palate is more commonly associated with other congenital defects than isolated cleft lip or cleft lip and cleft palate.