Need for checking

Question

My husband is a carrier of the DF508 CF mutation. We have both been checked for the 75% of CF mutations, I with negative results. Our son, according to the results of the amniocentesis does not carry the mutation of his father, and the IRT results were negative as well.
Does the child need to have a sweat test, if we take into account the fact that he is nearly below the lowest growth curves for height and weight? He does not present any clinical symptoms of the disease, but I believe that he has an especially salty forehead (I was told that this may be an indication for CF). Is there any chance that I may be carrying a CF mutation that is not included in the 75% percentage I was checked about and the child may carry an undetectable gene as well? The child is 2.5 years old.

Answer

Dear friend,
Your husband is a carrier of the DF508 CF mutation, and you have been checked for the 75% of CF mutations with negative results. You child does not carry the CF mutation of his father, which means that it has inherited the healthy chromosome from his father, who is a simple carrier of the disease, therefore your son does not suffer from CF.
You also mention that the IRT test was negative as well.
All the above exclude the possibility that your son has CF.
The low weight and height of your son must me evaluated by the pediatrician, in combination with other factors, such as if it was a premature delivery, the weight and height at birth, the weight and height of the parents, etc.
I would advise you, in the event of another pregnancy, to have yourself checked for all the mutations, or to seek genetic counseling from an experienced center.
Dear friend, all sweat is salty, as is your child’s sweat. The sweat of a child with CF is comparatively a lot more salty than the salty sweat of other people.
Yours friendly,
Dr. Stavros Doudounakis

15.11.2012