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 of 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
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?