Cleft lip and palate: What are the causes?

My sister's son was born with a cleft lip. What causes cleft lip and cleft palate? Can they expect feeding problems?

Question:

Cleft lip, with or without cleft palate, is a congenital malformation that affects about 1 in every 700 live human births in the United States each year. Clefts occur more frequently among Asians (about 1:400) and certain American Indians than Europeans. Clefts are relatively less common among Africans and African Americans (about 1:1500).

Generally, facial clefting results when medial, lateral, and maxillary nasal processes on either left, right or both sides of the forming craniofacial complex do not fuse completely. Early embryonic changes (during the fourth and tenth weeks of gestation) may result in clefting. Suspected causes include: 1) environmental insults (i.e. maternal diseases, chemotherapy, radiation, alcohol, excess retinoic acid and anticonvulsant medications); or 2) genetic factors.

Researchers have identified some of the genes involved in regulating craniofacial development. The Human Genome Project hopes to ultimately identify all the genes that make us human. This should help us to better understand the genetic causes of cleft lip and palate.

Factors that increase the chance of congenital malformations include: 1) pregnancies in women older than 35; 2) teenaged pregnancies; and 3) increased consumption of teratogens during early months of pregnancy (Slavkin 1992).

The good news is that ultrasound, amniocentesis and molecular genetic techniques can be used to detect common congenital malformations, including cleft lip, early. Advances in surgical techniques and growth factors also help correct problems associated with cleft lip or cleft palate. Cleft lip is usually less serious than cleft palate. A post-pubescent male may choose to grow a mustache to hide the external scar that remains after childhood surgery has closed the cleft lip. Unfortunately, this easy cosmetic option is not available to females.

About 22 percent of facial clefting has a genetic origin. Again, most cleft lips with or without cleft palate are produced by environmental insults (teratogens such as alcohol, retinoic acid, maternal illness, protein/calorie malnutrition during pregnancy) interacting with one or more genes. There is increased risk for congenital malformations because of maternal age at the time of pregnancy.

Additional risk factors include lack of prenatal care during pregnancy, cigarette smoking, lack of a balanced diet and the chronic use of non- prescribed drugs or substance abuse. If parents without a cleft have a child with a cleft, the chance that a subsequent baby will have a cleft is only two to four percent. If either parent has a cleft, the relative risks become about four to five percent for having a baby with a cleft. If both parents have clefts, the risks are much greater (Slavkin 1992).

In addition to the required tissue repair, children with cleft lip and palate may have difficulty hearing or speaking clearly. Thanks to professionals including dentists, surgeons, and teachers, prognosis is very good. Patients with isolated cleft lip usually do not have trouble with feeding. However, infants with cleft lip and palate don't have adequate suction to draw milk through a nipple. Methods have been developed to enhance maternal bonding during the feeding of newborn and very young infants.

I am glad to answer your question because it provides an opportunity to reduce the incidence of cleft lip and cleft palate through public education. Families with a history of facial clefting should seek genetic counseling to determine the relative risks. Older women and women with diabetes and epilepsy should know about maternal age risk factors.

For additional information and support:

References

  • Scapoli L. et al., Lack of linkage disequilibrium between transforming growth factor alpha Taq I polymorphism and cleft lip with or without cleft palate in families from northeastern Italy. Med Genetics 1998; 75(2):203-206.
  • Slavkin, HC Incidence of cleft lips, palates rising. J Am Dent Assoc 1992; pp. 61-65.
  • Bixler D. Genetics and clefting. Cleft Palate J 1981;18:10-8.
  • Diewert VM. Craniofacial growth during human secondary palate formation and potential relevance of experimental cleft palate observations. J Craniofac Genet Dev Biol 1986;2:267-76.
  • Burdi AR, Lawton TJ, Grosslight J. Prenatal pattern emergence in early human facial development. Cleft Palate J 1988;25:8-15.
  • Slavkin HC. Regulatory issues during early craniofacial development: a summary. Cleft Palate J 1991;27:101-9.
  • Shuler CF, Guo Y, Majumder A, Luo R. Molecular and morphologic changes during the epithelial-mesenchymal transformation of palatal shelf medial edge epithelium in vitro. Int J Dev Biol 1991;35:323-32.
  • Fraser FC. The genetics of cleft lip and palate. Am J Hum Genet 1970;22:336-52.
  • Slavkin HC. Morphogenesis of a complex organ: vertebrate palate development. Cur Top Dev Biol 1984;19:1-16.
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