Cleft lip and cleft palate is common in the U.S., occurring in 1 of every 600 live births in this country. Clefts are much more common in Native American and Asian populations, and less common in those of African heritage. Cleft lip is associated with cleft palate in two-thirds of all cases. Cleft lip, with or without cleft palate, occurs more often in males, whereas isolated cleft palate is seen more often in females.
When the palate, or roof of the mouth, forms in the fetus, the sides of the palate form first. Then the sides grow towards the midline and fuse, forming an intact palate. But when this process is disrupted, the palate doesn’t fuse completely, resulting in a cleft or hole in the palate. In utero, the upper lip is fully formed by the sixth week of gestation, while the palate is fully fused by the fifth to twelfth week of gestation.
Clefts can be seen in isolation or as part of syndrome that includes other anomalies or medical problems. Cleft lip can be found as part of more than 200 syndromes, and a cleft palate (without cleft lip) is part of more than 400 syndromes.
CAUSES OF CLEFT LIP AND PALATE
The development of the lip and palate is a complicated process, and the origin of clefts is often multifactorial.
Genes & Syndromes
Several genes have been linked to cleft lip and palate. Some cases are familial, but others are due to new mutations of one or more of these genes.
Certain syndromes include cleft lip or palate as part of the constellation of anomalies. Some of these syndromes include, but are not limited to:
- DiGeorge syndrome
- Trisomy 13
- Treacher Collins syndrome
- van der Woude syndrome
- Stickler syndrome
- Smith-Lemli-Opitz syndrome
- Ectodermal dysplasia
- Pierre Robin syndrome
However, the majority of cleft lips and palates are not due to a syndrome. Two-thirds of those with a cleft lip (with or without a cleft palate) are not due to syndromes, and about half of those with an isolated cleft palate are not due to syndromes.
The role of external influences is still largely unknown, but some toxins are well documented to contribute to clefts. Smoking during pregnancy is a well-known cause of cleft lip and palate, and several studies have shown a link between alcohol use during pregnancy and clefts. Some industrial pesticides have been implicated in cleft development.
Medicines, such as phenytoin, benzodiazepines, and phenobarbital have been shown to cause clefts. Corticosteroid use in pregnancy has also been linked to clefts.
Some viral infections in the first trimester may lead to inflammatory changes that have been linked to cleft formation.
This is another area that is not entirely clear, as it is difficult to perform studies isolating a single nutrient as a possible cause. However, multiple studies have shown that regular consumption of a multivitamin during pregnancy reduces the risk of clefts. Low levels of vitamin B6 has been linked to cleft development. Zinc deficiency causes cleft lip and palate in animals, and some studies suggest there is a link in humans, as well.
Folate or folic acid is another nutrient that may be protective against clefts. Folate deficiency causes clefts in animals. In North America, folic acid fortification was mandated starting in the late 1990s, and since then, there has been a decrease in cleft lip and palate in the U.S., but not in Canada. However, one study suggested that too much folate can increase the risk of clefts.
TREATMENT OF CLEFT LIP AND PALATE
Once cleft lip or palate has been identified, the first task is to determine if this is an isolated finding or due to a syndrome, as that will determine the prognosis. If the cleft is due to a syndrome, the next step is to determine the extent of the other anomalies.
The work up and treatment of cleft lip and palate should be conducted by a multidisciplinary team that may include a plastic surgeon, oral and maxillofacial surgeon, dentist, orthodontist, ear nose & throat surgeon, neurosurgeon, geneticist, nutritionist, and child development specialist. As part of the evaluation, vision and hearing tests should be done as soon as possible.
Surgery is the only treatment option, and is necessary to ensure optimal feeding, breathing, speech, and cosmetic results. Although there are many variations in the surgical repair of cleft lip and palate, a staged closure of the clefts with multiple procedures is the most common therapy.
Cleft lips are usually repaired at about 10 weeks of age, with cleft palates usually repaired between 9-12 months. The benefits of early cleft palate closure (such as better speech outcomes) need to be balanced against the risks of complications of early repair (such as formation of fistulas, or little tunnels that extend from the palate and are often difficult to close).
Nutrition before and after cleft repair is critical, as feeding can be difficult. Infants with cleft lip and palate can be breast fed, but it is uncommon to exclusively breast feed these babies before surgical correction. Babies with clefts take in more air when feeding, so they need more frequent burping. There are many aids available to help feed these babies, such as squeezable bottles and special nipples.
The medical team will need to monitor the baby’s growth closely, and the family may benefit from help from a feeding specialist. Parents should be aware that babies with clefts often have the feeding come back through the nose, and this usually is not a concern.
Children born with cleft lip and palate can have multiple health consequences, even after surgical repair, including ear tube dysfunction, chronic ear infections, hearing loss, and speech delay. Often these children will require placement of ear tubes, and will need their hearing tested annually or even twice a year.
Special mention must be made about a small subset of clefts known as a submucous cleft palate. This is a cleft of the soft palate that is located above the roof of the mouth and therefore is not visible to the naked eye. Signs of a submucous cleft include a notched or high-arched palate and a bifid uvula. It is important to identify a submucous cleft because it can have a profound effect on speech.
Because of the cosmetic issues, cleft lip and palate can have significant social and psychological consequences. Parent support groups and peer groups can be helpful. One valuable resource for parents and patients is the American Cleft Palate-Craniofacial Association (ACPA) website which has a lot of resources.
The recurrence risk for subsequent siblings in isolated cleft lip or palate is low, about 2-4%. The recurrence risk is higher with clefts due to syndromes, depending on the type of inheritance of the particular syndrome.