Cleft lip and cleft palate are two of the most common congenital defects. A cleft lip is a split in the upper lip, and a cleft palate is an opening or split in the roof of the mouth. Cleft lips and palates occur when the facial structures do not close during fetal development.
Cleft lips and palates can occur individually or in conjunction with one another. The incidence rate of cleft lips, with or without cleft palates, is 1 in 700 births. 50% of cases of cleft lips also have a cleft palate. An isolated cleft palate has an estimated incidence rate of 25-40%, and 80% of cases occur on one side, with the left side being two times as frequent. Cleft lips and palates occur twice as often in males than females.
70% of cleft lip and palates are considered isolated, or non-syndromic, meaning that they do not occur in conjunction with other disorders or anomalies. Cleft lips and palates are not fatal, but 30% of cases are considered syndromic, meaning that they occur in conjunction with other anomalies and malformations.
There are over 400 single-gene disorders that are associated with cleft lip and palates. Cleft lips and palates are commonly associated with aneuploidy. Clefts are present in 75% of trisomy 13 cases, 15% of trisomy 18 cases, and 1.5% of trisomy 21 (Down syndrome) cases. Clefts are also associated with malformations of the central nervous system, heart, kidneys, skeleton, and abdomen.
Recurrence risk is dependent on the underlying cause, whether the clefts are syndromic or isolated. Folate has been shown to decrease the incidence of facial clefts. Genetic testing and genetic counseling are recommended prior to subsequent pregnancies.