Orofacial cleft

Overview of orofacial cleft

The Center for Disease Control and Prevention reports that nearly 3-6% of the infants worldwide are born with some serious birth defect(s). Facial defects and neural tube defects are the most common forms of birth defects found in newborns. The most prevalent form of birth defect is orofacial cleft. The incidence rate is twice as common in Asians than the Caucasians. Surgical interventions are necessary for the majority of these cases to rectify the structural defects and enable these children to lead a normal life.

What is orofacial cleft?

An orofacial cleft is a collective term for a group of conditions that encompass structural defects of the lip, palate or both. Cleft lip is a condition characterized by an opening in the upper lip, that may even extend to the nose. This opening may be unilateral (on one side) or bilateral (on both sides). It may also be found in the middle in many cases.

A cleft palate is a condition in which there is an opening on the roof of the mouth that extends into the nose. Orofacial clefts are common in about 1 to 2 per 1000 live births in the developed countries. Cleft lip and cleft palate can result in a number of complications such as problems in speech formation, auditory problems, ear infections and feeding problems. In many cases, this condition is associated with other disorders.

What are the main causes of orofacial cleft formation?

Both cleft palate and cleft lip are outcomes of the poor or incomplete joining of the tissues of the face in the stage of fetal development. Certain risk factors such as drinking or smoking during pregnancy, overweight conditions, metabolic diseases (diabetes) and having a child after 35 can increase the possibilities of orofacial clefts.

Some of the main factors are discussed here

Morphological defects

During the first 6-8 weeks of pregnancy, the following five primitive tissue lobes are expected to grow-

• Frontonasal prominence: From the top of the head to the upper lip
• Maxillar prominence: Two from the cheeks, that join with the first lobe to form the upper lip.
• Mandibular prominence: Two additional lobes growing from each side that form the chin and the lower lip.

If any of these tissues fail to join or are poorly formed, a gap appears at the site where the fusion of the tissues should have occurred. This can take place at a single or at multiple sites. This results in birth defects characterized by fusion failures and a malformed face. These conditions are exacerbated by a number of factors such as-

• Nutritional deficits
• Environmental pollution
• Toxic substances
• Alcoholism or tobacco smoking

Genetics

Orofacial cleft conditions are often found to run in families, though the exact genetic linkage in such cases has not been fully identified. The genes involved in the midfacial development are believed to be responsible for the midfacial clefts.

Recent genetic studies have shown the involvement of the cleft lip and palate transmembrane protein 1 and GAD1 in orofacial clefts. Some other studies have established the role of the mutations in the HYAL2 gene in the formation of clefts. Certain sequence variants in the genes IRF6, PVRL1 and MSX1 are also found to be responsible for orofacial cleft formation in the isolated cases.

Syndromes

Cleft lip and cleft palate can be the outcomes of the following syndromes-

• Stickler’s syndrome: It can cause cleft lip, cleft palate, myopia and joint pain.
• Loeys–Dietz syndrome: Can cause bifid uvula, aortic aneurysm, and hypertelorism.
• Hardikar syndrome: Cleft lip and palate, Hydronephrosis and intestinal obstruction.
• Patau syndrome
• Malpuech facial clefting syndrome
• Popliteal pterygium syndrome
• Treacher Collins syndrome 

What are the different types of orofacial clefts?

The different types of cleft lips and cleft palates are described below-

Pre-alveolar cleft: It is also known as “cleft of the lip” or CL. It has the following subtypes-

• Unilateral: On one side
• Bilateral: On both side

A cleft lip is known as incomplete when it does not extend till the external nares (nostrils). A complete cleft lip, on the other hand, extends to the floor of the nose. A complete CL results in the widening and the flattening of the affected nostril. The columella is shortened in this case.

Post-alveolar cleft: It is also known as cleft palate or simply CP. It has the following subtypes-

• Cleft of the uvula
• Partial cleft (involves only the soft palate)
• Complete cleft (soft and hard palate)
• Submucous cleft

Alveolar cleft: It is commonly known as the cleft of the lip, alveolus and the palate. It has two subtypes-

• Unilateral
• Bilateral cleft lip and palate

Diagnostic tests

Generally, the diagnosis is done by a thorough physical examination at the time of birth. The recent advances in genetics and treatment techniques have enabled the detection of an orofacial cleft in the gestational period by means of prenatal ultrasonography.

Treatment

Cleft lip and palate are generally curable. Cleft lip can be treated by surgery after 2-3 months of birth to close the fissure. Two surgeries may be necessary if the cleft lip is bilateral. Nasoalveolar molding is necessary before the surgery in order to maintain the nasal-symmetry.

For cleft palate, a prosthetic device known as the palatal obturator is used to cover the cleft palate temporarily. Around 20-25% of the patients require only one palatal surgery. The rest may require repeated surgeries to enable the generation of non-hypernasal speech. For those children suffering from hearing problems due to clefts, a tympanostomy tube is inserted into the ear-drum in order to improve the auditory functions. An orofacial cleft can lead to a number of complications that are more common in females. It may lead to poor speech development and auditory problems. Surgical treatments should be carried out at a very early stage in order to prevent the condition from worsening.

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