Cleft lip and cleft palate are both birth defects of the mouth. The
combination of cleft lip and cleft palate is one of the most common birth
defects. Although research continues on specific causes of cleft lip and cleft
palate, they may result from sporadic or inherited genetic mutations or from
certain maternal environmental exposures (for example, from smoking) during
Both of these birth defects form early in fetal development and can
occur independently of each other (isolated) or in combination.
Cleft lip is one or more splits (clefts) in
the upper lip. Cleft lip can range from a small indentation in the lip to a
split in the lip that may extend up into one or both nostrils. Cleft lip
develops in about the sixth to eighth week of gestation, when structures in the
upper jaw do not fuse properly and the upper lip does not completely merge.
Sometimes the nasal cavity, palate, and upper teeth are also affected.
Cleft palate is an opening in the roof of the
mouth that develops when the bones and tissues do not completely join during
fetal growth, sometime between the seventh and twelfth weeks of gestation. The
severity and type of cleft palate vary according to where the cleft occurs on
the palate and whether all the layers of the palate are affected. A mild form
of cleft palate may not be visible because tissue covers the cleft. A complete
cleft palate involves all layers of tissue of the soft palate, extends to and
includes the hard palate, and may continue to the lip and nose. Sometimes
problems linked with cleft palate also include deformities of the nasal
cavities and/or the partition separating them (septum).
Cleft lip, whether isolated or occurring with cleft palate, is more
common in males; isolated cleft palate occurs more often in females. Cleft
palate-with or without cleft lip-is sometimes linked with other health
conditions, such as fetal alcohol syndrome or chromosomal syndromes like trisomy 13 and 18.