cystic fibrosis-genetics

Question

What does amplification of exon 3,4,10,11,19,20,21 mean on CFTR gene, no mutations were found. This analysis was sent to France (so does the laboratory say). They said that they will sent it in France for complete DNA sequencing for cystic fibrosis at LGNA (IGNA) in France, at Prof Jean Paul Moisan, that cannot be reached by phone, and these results were sent without complete DNA sequencing and no other explanation. If there is any one that can bring us some informations we would be grateful.

Answer

Hello,
There are situations in which the genetic test is not conclusive for the diagnosis of cystic fibrosis, for multiple reasons. The most frequent situation is that in which not both alleles are found. The unknown allele is either rare, either not caught in the utilized kit, either a polimorphic allele etc.
In this case, the exons 3,4,10,11,19,20,21 of the CFTR gene have been amplified with the so-called PCR-method and have assumably then been sequenced. After this amplification and investigation, no mutations were found in the named exons. Therefore, it may be possible, that in the non-investigated exons there might be a mutation which causes CF. Therefore, in some well documented situations the full DNA analysis can be done, this is a very complicated and expensive method. The most qualified person to give you explanations is the doctor that asked for the genetic test or the personnel of the laboratory where the sample was collected.
Sincerely yours, Prof.Dr.Liviu Pop

26.05.2011