Medical Q&As

Cystic fibrosis - gene testing?

Is it possible to have a test done to determine if someone is a carrier of the recessive cystic fibrosis gene?

It is possible to detect the cystic fibrosis gene by testing a sample of blood or saliva. The relevant gene is known as CFTR (cystic fibrosis transmembrane regulator) gene. It is estimated that approximately 1 in 20 members of the Irish population are carriers for the gene. Race or ethnicity influences the chance of being a carrier for cystic fibrosis. For example if a person was of Asian extraction the chance of being a carrier would be of the order of 1 in 90. The cystic fibrosis gene is a recessive gene, which means that each parent must be a carrier for the gene in order for them to produce a child with cystic fibrosis. If both parents are carriers there is a 1 in 4 chance that the child will have cystic fibrosis and there is a 1 in 2 chance that the child will be a carrier. It is important to stress that there are no health implications for a child who is a carrier of the gene. In other words carriers do not develop any of the health problems associated with cystic fibrosis. There are over 800 mutations of the cystic fibrosis gene some of which cannot be detected through gene testing. However, these unknown cystic fibrosis mutations are rare. Therefore if you went for gene testing and were given a normal result the chances of having one of these unknown mutations would be extremely small.