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Cleft
happens more often among Asians (one in 500) and least often in persons of
African heritage (one in 1,000), and one in 700 among European.
Heredity: Only 15-20% of the patients have family history of another relative
having cleft. Most of the cleft occur without any family history. Genetic
predisposition plays an important role.
Face shape: The shape of the front of a person's face is somewhat race-specific.
It is thought that because Asians have a flatter facial plane, they are more
susceptible to clefting. The problem with that theory is that it would then
make more sense that the Europeans, with the more angled plane (i.e., bigger
noses) would be the least affected. That is not the case.
Environmental factors: Poor maternal health is considered an important factor. This supported by the fact that cleft occurs in socio-economically poor countries. Again, the problem with this theory is that there are some very poor African nations too, and African Americans are also among the American poor as well. However the cleft is not very common in African.
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.
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.
About 20% percent of facial clefting has a genetic origin. Again, most cleft lip 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.
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