This information has been designed to give a brief overview of genetic testing and consent. If you have any questions or if you would like to discuss anything in further detail, please feel free to ask your genetics doctor or nurse.
What is a genetic test?
Some medical conditions can be caused by changes in your genes or chromosomes. Sometimes this can be inherited from one or both of your parents, or sometimes it begins for the first time in you. A genetic test is performed on a blood sample and examines your genes or chromosomes.
What are genes and chromosomes?
Our genes are the unique set of instructions inside our bodies that make each of us different.
There are many thousands of genes, each carrying a different instruction. As well as controlling the way we look, our genes control the way each part of the body works. Genes are made of a chemical called DNA (which is short for ‘deoxyribose nucleic acid’).
Genes lie on tiny structures called chromosomes, rather like beads threaded onto a string. Each chromosome contains thousands of genes. Each cell has two copies of each chromosome and gene because we inherit one copy from each parent.
Our personal genetic "make-up" - the pattern of genes and chromosomes - remains the same throughout our lives: from the moment we are conceived right up to the end of our lives.
Are there different types of genetic test?
Yes. There are three main types of genetic test:
The purpose of a diagnostic genetic test is to try and discover the cause of your medical condition. If the underlying cause can be found, this may help to plan further healthcare, although this is not always the case.
Presymptomatic (or Predictive) Tests
A predictive genetic test is one that is performed on you if, although you are currently healthy, you are known to be "at risk" of developing a particular inherited condition at some point in the future.
It is possible to "carry" an altered gene or chromosome pattern that causes you no harm but may cause problems in your children, who inherit some of your genes and chromosomes. A genetic carrier test is one that can identify a healthy "carrier" whose children could be affected with a particular genetic condition.
Consent and genetic testing
Before you give a blood sample for genetic testing it is important that you understand what will happen to your blood sample, how you will be given the result of the test and what the implications of the test result might be. We only perform genetic tests with your consent.
How is the blood sample taken?
Having a blood sample taken for a genetic test is the same as for any other blood test. For adults, no preparation is necessary. For children who need to have blood taken, this will usually be done using local anaesthetic cream to numb the skin. The genetic doctor or nurse will take the sample in clinic or at home. It usually takes a minute or two to take the blood sample. You may feel a little discomfort when the sample is taken and may develop a small bruise at the site where the sample was taken.