Cystic fibrosis: faulty genes are in the family

Recent publicity about cystic fibrosis has made me wonder. A distant cousin was born with cystic fibrosis about 20 years ago. He died in his teens. My sister and I are now in our mid-twenties and we will both probably have children within the next couple of years. Is there a chance we could have a child with cystic fibrosis? Is there a test we could have to find out?

Dr Fred Kavalier answers your health question:

Cystic fibrosis (CF), a genetic condition, only develops if a child inherits two faulty copies of the CF gene, one from the mother, one from the father. People who carry only one faulty copy are unaware of it, as it causes no harm or symptoms. If your distant relative had cystic fibrosis, your chance of carrying a faulty gene is higher than average. In the UK, about one person in 25 carries a faulty CF gene, whereas your chance of being a carrier is about one in 16. If you are a carrier, this will only cause problems if your partner is also a carrier. You could ask your GP to refer you for a CF carrier test.

Please mail your questions for Dr Fred to health@independent.co.uk. He regrets that he is unable to respond personally to questions.