What is clefting?
Cleft lip is defined as incomplete closure of the lip during fetal development. It can occur alone (cleft lip) or can extend into the gumline and roof of the mouth (cleft lip and palate).
Clefting of the back of the palate (posterior palate) alone is defined as incomplete closure of the roof of the mouth in a developing embryo (incomplete fusion of the palatal shelves).
When does clefting occur?
The lip and palate should close between six to twelve weeks of fetal development and in individuals with a cleft of the lip and/or palate this process does not complete itself, leaving a gap that is open.
How often does clefting occur?
Clefting of the lip and palate are thought to be separate events that have different developmental causes.
Clefting of the lip with or without clefting of the palate occurs in about 1 in 1000 Caucasian individuals.
Clefting of the posterior palate alone occurs in approximately 1/1500-2000 Caucasian individuals.
Clefting occurs more frequently in Asian and Native American populations (1/500 individuals) and less frequently in African Americans (1/2500 individuals).
Clefting of the lip with or without cleft palate occurs more frequently on the left side and more often in males than in females. Posterior cleft palate occurs more frequently in females than males. Of all individuals with clefting, approximately 50% have clefting of the lip and palate, 25% have clefting of the posterior palate alone, and 25% have clefting of the lip alone.
What complications can occur as the result of clefting?
Newborns may require some assistance to aid in breastfeeding or special nipples on bottles to allow for proper feeding. Children with a cleft typically undergo a series of surgeries and orthodontic procedures to properly close the cleft, allow for appropriate dental development, and ensure a good cosmetic outcome.
What medical specialists may be involved in the care of an individual with a cleft?
Many medical facilities may have craniofacial teams, made up of several medical specialties, to properly care for and manage the medical care for individuals with clefts. These teams often consist of plastic surgeons, orthodontists, dentists, prosthodontists, oral and maxillofacial surgeons, geneticists, genetic counselors, social workers, psychologists, otorhinolaryngologists, speech pathologists, and any other specialists that a patient may require based on his or her unique needs.
How would someone with a personal or family history of clefting benefit from seeing a geneticist or genetic counselor?
Individuals with clefting can be evaluated in a genetics clinic to look for the presence of any physical differences or features suggestive of a syndromic cause of clefting. This is important in order to determine if a patient could have additional medical problems that may need to be addressed and to provide families with accurate medical information and recurrence risks. The majority of clefting is isolated, however 2-10% of individuals with clefts of the lip and/or palate may have other physical malformations or health problems and there are over 300 syndromes that are associated with clefting. Approximately 70% of cases of cleft lip with or without cleft palate are isolated and non-syndromic. About 50% of posterior cleft palate alone is isolated and non-syndromic.
When not associated with a specific syndrome, the cause of clefting is thought to be multifactorial, meaning it results from a combination of both genetic vulnerability and poorly defined environmental factors.
What are the recurrence risks associated with clefting?
After a couple has a child with a cleft, the chances of having additional children with a cleft are dependent on whether the child's clefting is due to a genetic syndrome or if it is an isolated birth defect.
Syndromic causes of clefting can be inherited and passed on in different ways. If an individual has a dominant condition associated with clefting, they may have up to a 50% risk to have a child with a cleft as well. If clefting is caused by a recessive condition, the risk may be up to 25%.
In the case of isolated, non-syndromic clefting, recurrence risk estimates are often based on studies of families with an individual with a cleft that look at how often additional children with clefting are born. If a couple has one child with a cleft that appears to be isolated and non-syndromic, their risk for an additional child with a cleft is approximately 2-4%. This is also the risk for an adult individual with a cleft to have a child who also has a cleft. If a couple has two children with a cleft, or if they have one child with a cleft but one of the parents has a cleft as well, their risk is closer to 12% for additional children with a cleft.
Why is it important to know whether a cleft is due to a syndrome or is isolated?
Knowing this information may help provide more accurate recurrence risks to families or individuals with a cleft who are planning a family. It is also important to accurately diagnose syndromic causes of clefting because this may alter medical management for patients. For example, if an individual with a cleft is found to have a syndrome that is associated with kidney malformations, it would be important to have a renal ultrasound performed to assess for any problems with the kidneys.
What genetic testing might be considered for an individual with clefting?
If a physician thinks that an individual has a syndromic cause for their clefting, syndrome-specific genetic testing may be available. Other genetic tests, such as chromosomal microarray, which look for genetic imbalances, may also be offered for patients with birth defects such as clefting. Most genetic testing related to clefting is performed on blood specimens.
To schedule an evaluation related to clefting:
Locate a genetic counselor from Minnesota at mygenepool.org or ask your doctor for a referral. Genetic counselors from Minnesota and elsewhere can also be located using the ‘find a counselor’ features at nsgc.org. Contact information for medical geneticists can also be found at www.acmg.net.