Transmission of the defective gene

Question

My granddaughter has cystic fibrosis. Would it be possible that me, her paternal grandmother, I transmitted it because I'd be carrier of the defective gene that I would have transmitted it to my son?
Thank you in advance for your answer.

Answer

Hello,
Any person with CF is carrier of 2 CF causing mutations, one transmitted by the father, the other one transmitted by the mother.
One CF causing mutation of your granddaughter has been transmitted from her father (your son) who received it either from his father or his mother, namely you. The probability that yourself have passed the CF mutation to your son is 1 in 2. Only research of the CF mutation on a sample of your blood could give you the answer. The answer to this question may be important for the information of relatives about the risk that they are themselves carrier of a mutation they may transmit to their offspring.
This search can be done by a molecular genetics laboratory accredited to perform this search for CF mutations.
I suggest you contact your GP or the CF Center physician who follows your granddaughter to get the contact information of the molecular genetics laboratory nearest to your home.
Sincerely,
Dr. Gilles Rault

23.12.2013