This information has been designed to provide information about chromosome tests. If you have any questions please feel free to ask the cleft nurse who will put you in contact with a member of the genetics team.
Why has my child been born with a cleft?
In most children no single cause for the cleft can be found. It is thought that most clefts are caused by a combination of many different genetic and environmental factors. Research is currently going on to try to understand these better. In a few families there is a strong inherited tendency to cleft lip and palate. A small number of babies are born with a cleft lip and/or palate because they have a chromosome abnormality.
What are genes and chromosomes and why are they important?
Genes can be thought of as the ‘blueprint’ for the body. The genes are composed of deoxyribonucleic acid, usually abbreviated to DNA. Each person has around 25,000 genes, which work together like a special computer programme to determine everything about us.
For example, how many fingers and toes we have, how short or tall we are and the colour of our eyes. Genes are so small that they cannot be seen even under a powerful microscope.
They are packaged inside larger structures called chromosomes. Unlike genes, chromosomes can be seen under a microscope. Every cell in our bodies contains a set of 46 chromosomes. They come in pairs. One of each pair comes from the mother and the other from the father. This is how we inherit characteristics from our parents. If a small piece of a chromosome is missing or there is an extra piece of any of the chromosomes this is likely to cause birth defects and/or learning difficulties.
The following picture shows what chromosomes would look like if we arrange them in pairs in order of their size.
What is a chromosome test?
The test allows us to produce a picture of your child’s chromosomes like the one above. We can see whether any of them has a piece missing or an extra piece.
Any abnormality found might explain why the cleft happened.
Why is the chromosome test so important?
- If we find a chromosome abnormality it is more likely that your baby will have problems with other areas of the body including learning difficulties. It is important to know about this so that any potential problems can be picked up and treated as soon as possible.
- If we find a chromosome abnormality we will understand why the cleft happened.
How is the chromosome test done?
The chromosome test requires a small blood sample. All babies have blood taken either before or during surgery and the chromosome sample can easily be taken at the same time.
The blood will be taken by one of the junior doctors while your baby is on the ward or under anaesthetic. Local anaesthetic cream is applied before the test to numb the skin.
Sometimes a small bruise will appear after the blood is taken but this will heal in a couple of days.