Cleft lip or palate is a congenital defect. The incidence rate is considerable high (1 in 700 live births traditionally quoted in western European literature) and in fact, is considered amongst the most common defects worldwide.
Moreover, the incidence rate varies depending on the ethnic origins and geographical region. The chance for any couple having a child with a cleft or lip palate is around one in six thousand (without any genetic predisposition from parents). The incidence rate of cleft or lip palates due to genetic issues is around 22%.
Children born with a cleft lip or cleft palate usually immediately commence treatment via surgery which can sometimes go on until they are in their teens. Often treatment will involve orthodontists, maxillofacial surgeons, the assistance of speech therapists and sometimes even psychologists. Cleft lip repair usually occurs at around 3 months with palate repair at 6-9 months.
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Twin zygosity studies have confirmed a higher incidence rate amongst monozygotic twins (twins with identical DNA profiles) than dizygotic twins (twins with non-identical DNA profiles). These findings show the existence of a strong genetic component. This is not, however, to exclude the influence of environmental factors (such as smoking or alcohol consumption during pregnancy or niacin deficiency) or the interaction of both genetic and environmental factors in the development of the condition. Cleft palate or lip syndrome may be due to inheritance factors where the fetus inherits the gene from one or both of his parents. The cause can, however, be a random gene mutation.
The inheritance pattern
Cleft palates run in families. However, it is hard to determine exactly how likely a child is to be born with a cleft palate basing oneself simple on the fact that another blood relative might have suffered from the condition. We need to look closely at the following factors: How close is the relationship between the people? How many biological relatives have suffered from the condition? What are the ethnic origins as well as the gender of the people affected?
cheiloschisis A cleft lip can occur on one or both sides of the lip. The palate remains unaffected. Typically, it appears as a small indent on the lip, although the size may vary depending on the case. In some cases, the indent may extend all the way up to the nose. This means that the mouth and nasal tubes are actually lead into each other.
A cleft palate is caused by incomplete fusion of the bones in the skulls which are responsible for forming the palate of the mouth. It may appear as a gap in the jaw or an actual hole in the mouth. In some cases, both a cleft lip and cleft palate may appear together in the same individual.
The Genetic component Scientists have for long tried to determine through advanced genetic testing and DNA analysis which genes are responsible for this congenital disorder. They have in the recent years, identified genes responsible for the formation of the mouth, jaw, and skull – the genes which are crucial to proper craniofacial development.
Studies, mainly centering on mice, have begun to unravel the molecular basis and causes of cleft syndromes resulting in the identification of a number of genes located at different locations on the human genome such as IRF6, a gene which enables the production of an important protein requirements for the formation of connective tissue (such as the tissue used to create the palate). The formation of the skull, jaw, and face is an extremely complex part of fetal development. An interference with the development of the complex and delicate interaction of factors that lead to a healthy formation of the face and cranial structures may cause a cleft lip or palate.
We currently have a number of genetic predisposition tests which assess how likely someone is of having a child with certain conditions in instances where there is a hereditary illness in the family. Prenatal care specialists and clinics, in fact, offer preconception genetic counseling to help couples discover whether there are any chances of having a baby that suffers from an inherited chromosomal abnormality of a genetic disorder. However, there is no DNA test that can as yet, assess this risk with regards to cleft and lip palate.
During pregnancy, ultrasonography can at times reveal whether the fetus is suffering from a cleft palate – however, the position of the fetus, as well as the sophistication of the machine, play an important role.