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Progression with R553x/IVS8-5T-TG12 mutations
- Question
- Hello,
My daughter has been diagnosed with atypical cystic fibrosis. What does that mean?
Do you possibly have any experience with the mutations mentioned above?
Many thanks
C.M. - Answer
- Hello,
Generally speaking, “atypical cystic fibrosis” describes a disease that, like the typical (or classic) type of cystic fibrosis (CF), is caused by mutations in the CFTR gene, but that differs from the classic form in its progression. Patients with atypical CF always have at least one CFTR mutation which appears along with a remaining partial function of the CFTR protein.
In the case of the R553X/IVS8-5t-TG12 genotype, the R553X mutation is a typical CF mutation that leads to the typical form of CF if it is homozygous (i.e., passed on by both parents) or if it appears together with another typical CF mutation (i.e. if one parent passed on the R553X mutation and the other parent passed on another typical mutation).
IVS8-5T-TG12, on the other hand, is an atypical mutation. There are a number of scientific publications which show that people who have inherited IVS8-5T-TG12 from one parent and a typical mutation (such as R553X) from the other parent either show no symptoms at all, or symptoms that are often limited to the apparatus (mostly a lack of spermatic ducts in male persons affected), or they can get symptoms in several organs. The last case usually means a a “mild” form of CF, i.e. the disease shows significantly less strongly than in people with “typical” CF.
One has to add that the clinical picture varies greatly even with classic CF, of course. Neither typical nor atypical CF allow for a certain prognosis of individual progressions, as progression is usually influenced not only by the mutations in the CFTR gene, but also by other genetic and non-genetic factors. On the whole, however, one can say that with the genotype you are describing, it will be reasonable to use the term “atypical CF” and a “typical” progression of the disease is therefore unlikely.
Kind regards
Prof. Stuhrmann-Spangenberg - 06.09.2010
