This is a good question. When people are diagnosed with an ailment, it is typical to experience emotions from denial, anger, hopelessness, acceptance, and others. People often lose faith in traditional medicine and sometimes even seek homeopathic remedies. Cystic fibrosis is not my area, but I did study molecular genetics in college and pondered genetic therapy for other diseases. This is a very difficult question to answer. There are countless laboratories and scientists studying therapeutic options for cystic fibrosis throughout the world.
https://www.cff.org/Our-Research/Our-Research-Approach/
One of the reasons that restriction enzymes are not used to repair human genes is that these enzymes must be introduced into cells that live in the patient. As you may know, the enzymes would be required to affect only the cells and genes that are responsible for the disease. One specific difficulty is the delivery of the enzyme specifically into the affected cells. This can sometimes be done using a "viral vector". This means that a cold virus, for instance, can be genetically engineered to deliver genetic material into cells. However, genetic engineering and selective "in vivo" cell infection are theoretically possible. However genetic errors lead to mutations. And a genetic mutation is what led to cystic fibrosis.
There have, indeed been attempts at gene therapy with cystic fibrosis. However, it appears that improvement has thus far been modest. To learn more about this, I would recommend a PubMed website search. This is far more potent than a Google search for medical issues.
I found this article. It details a gene therapy study that demonstrated modest improvement in CF patients:
Repeated nebulisation of non-viral CFTR gene therapy in
patients with cystic fi brosis: a randomised, double-blind,
placebo-controlled, phase 2b trial
Jason Hess, MD, FACS
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