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Why can inserting a normal gene at the wrong chromosomal location create a new mutation?

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CRISPR-Cas9; gene editing — gene editing The CRISPR-Cas9 gene-editing complex from the bacterium *Streptococcus pyogenes*.

In the context of gene therapy, inserting a normal gene into a mutant nucleus often results in the gene integrating into a chromosomal site different from the defective allele.123

While this process is intended to repair a mutation, a new mutation can be created if the normal gene happens to integrate into another functional gene. By inserting itself into a functional gene, the new genetic material can disrupt that gene's sequence or expression, potentially leading to unintended biological consequences or the loss of that gene's normal function. This risk highlights the importance of precision in gene editing technologies, such as CRISPR-Cas9, which are designed to make highly specific changes to the DNA sequence to avoid such off-target effects.1234