Please note: While some information will still be current in a year, other information may already be out of date in three months time. If you are in any doubt, please feel free to ask.


Is it correct , that if one parent is not a carrier of the cf virus so to speak that the child can not possible have cf?
and is that 100% correct ?

Dear questioner,
first of all, CF (Cystic Fibrosis) is not! a transmittable disease caused by a “virus”—it is a hereditary disease that occurs due to genetic changes (mutations) in the so-called CFTR-gene. This gene codes for a chloride channel in the cell membrane and if not enough or unfunctional chloride channel is produced due to the genetic changes, sodium, chloride and water cannot properly be transported from the inside of the cell to the cell surface. The result is not properly hydrated secretions in many organs, mostly lung and pancreas are involved. In the lung, the sticky secretions lead to an impaired clearance of the airways from germs, so that chronic inflammation and damage of the lung tissue are the consequence. In the pancreas, the viscous secretions lead to damage of the organ and its insufficiency to release pancreatic enzymes, so that food cannot properly be digested, fat is excreted via the stool, that results in smelly, fatty stools, and consequently in a failure to thrive.
CF is a so-called autosomal-recessive disease, that means a person only suffers from CF, if both chromosomes (the one inherited from the father and the one inherited from the mother) carry a CF causing mutation. If a person has a CF causing mutation only on one of his chromosomes, he is in general a “ healthy carrier” of one CF mutation, most carriers are unaware of the fact that they carry such a mutation.
So in your question you address the case, that we have a couple and one parent is not a carrier of a CF mutation. If one could be 100% sure, that one parent is not carrying any CF mutation, this parent cannot inherit a CF mutation to his off-spring. Even if the other parent would be a CF patient (meaning both of his genes carry a CF mutation) and would always inherit one CF mutation to a further child, all those children would be healty carriers, as they always inherit a chromosome from one parent without a CF mutation. In case the partner of the person without CF mutations would be a carrier, 50% of the children will not inherit a CF mutation at all, and 50% will inherit one CF mutation from the carrier parent, but those will also be healthy carriers.
In summary, it is correct, that if one parent is not a carrier of a CF mutation, the possible children will not suffer from CF, they can be maximally carriers of a CF mutation if the other partner is a carrier or CF patient.
However, as you ask about 100% security, this is only 100% secure, if one of the parents is with 100% security not a carrier of a CF mutation. 100% security in medicine is nearly never possible, if one partner does a genetic screening test, he is tested for the most frequent CF mutations in the population. So if such a test is negative, a rest risk remains, that he is still a carrier, but the test could not detect his mutation. Even if then a complete gene sequencing is done to search for all known CF mutations, this risk is reduced markedly, and reaches nearly 100%, but fully 100% cannot be achieved by any test, as unknown CF mutations exist.
Hope to have answered your question,
Best regards,
Dr. Daniela d’Alquen (Coordinator of the central English Archive of ECORN-CF)