PHILADELPHIA — A number of serious diseases exist because of defects or mutations in our DNA. Curing such diseases could in principle be carried out by rewriting the DNA to fix the mutated base pairs. Yet until recently scientists have remained stymied in their attempts to directly modify genes in a living animal.

Findings described in the March 30, 2014 issue of Nature Biotechnology, however, reveal that a gene-editing technique, known as CRISPR  (Clustered Regularly Interspaced Short Palindromic Repeats), can be used successfully in mice to reverse disease symptoms for a liver defect known as type I tyrosinemia.

In humans, this potentially fatal ailment affects about one in 100,000 people. CRISPR, which enables researchers to snip out the mutated piece of DNA and replace it with the correct sequence, holds the potential for treating other genetic disorders as well.

Correcting mutations in DNA to remedy a serious medical defect would certainly be desirable and permissible. In 2008, in a document called Dignitas Personae, the Vatican’s Congregation for the Doctrine of the Faith agreed that trying to restore “the normal genetic configuration of the patient or to counter damage caused by genetic anomalies” would be morally acceptable as long as the person being treated will not “be exposed to risks to his health or physical integrity which are excessive...”

Our ability to rewrite the human genome at will through precise DNA editing techniques, however, does raise substantial concerns about misusing the technology. In fact, researchers are already discussing the possibility of going beyond therapies and treatments, and instead, using CRISPR and other gene-alteration technologies to enhance human characteristics.

For example, one possible direction would be to engineer changes in the genes of human muscles so that they could be worked harder and longer, thereby enhancing the performance of athletes and soldiers.

This kind of human re-engineering would cross an important line: instead of helping human beings who are struggling against serious diseases, scientists would now begin manipulating human beings for ulterior motives. As Dignitas Personae puts it, “such manipulation would promote a eugenic mentality and would lead to indirect social stigma with regard to people who lack certain qualities, while privileging [others].” The document also notes how attempting to create a new type of human being could unmask a dark and troubling ideology “in which man tries to take the place of his Creator,” resulting in an “unjust domination of man over man.”

The remarkable tools becoming available not only for genetic therapies but also for human enhancement projects and embryonic manipulation raise daunting ethical concerns about the subjugation of man to his own technology, and call for thoughtful measures and vigilance to ensure the proper use of these techniques now and in the future.

The writer is a priest of the diocese of Fall River, Mass., and serves as the Director of Education at The National Catholic Bioethics Center in Philadelphia.