Cf heterozygote carrier

Question

After CVS testing the baby is heterozygote carrier of CF. Will it be born ok, or are there any other testings to be done?

Answer

Dear friend,
First of all it has to be stated that in general, CF is an autosomal-recessive disease, that means that the child has to have a gene mutation of the CFTR genes on both chromosomes (one is inherited from the father, one from the mother) in order to suffer from the illness of Cystic Fibrosis. In general, if there really is only one mutation (like in your case stated after CVS), this is called "a heterozygote carrier" and the child will not suffer from CF and be born healthy.

Now the question arises why there has been a CF-carrier screening in your child; according to the guidelines, this kind of prenatal diagnosis is offered to parents who already have a child with CF, or parents who are identified to be each a carrier of the CF-gene through carrier testing. That means, that in both cases in general the mutations that are carried by each parent are known. Then the unborn child is tested for these specific mutations and if it has inherited both, it will suffer from CF. If both mutations that one has to search for are known and the result of the CVS shows the child has inherited only one, it is for sure a healthy carrier, will not suffer from CF and no further tests are needed.

There is normally no recommendation to test an unborn child just “for instance” for CF-mutations, without a family history or without testing the parents before. If one would still do a test on such a basis, there remains a small possibility, that there might be a second CF-mutation in the child, that has not been detected by the genetic screening test as the standard genetic test is investigating only a panel of 30-38 of the most frequent CF-mutations. Without information about the genetic status of the parents, the specific mutation to search for is unknown and can only be generally screened. If then, a carrier state is the result, it is possible to have the baby checked after birth by an IRT (this is a screening test from the blood for CF in newborns) or by a sweat test or extended genetic investigation if there is any doubt in the healthy carrier state. But this way of testing is not the standard situation.

Yours sincerely,

Dr. Stavros Doudounakis and Dr. Daniela d'Alquen

20.01.2012