The human genome has its own proofreaders and editors, and their handiwork is not as haphazard as once thought.
When DNA's double helix is broken after damage from, say, exposure to X-rays, molecular machines perform a kind of genetic "auto-correction" to put the genome back together -- but those repairs are often imperfect. Just as your smartphone might amend a misspelled text message into an incoherent phrase, the cell's natural DNA repair process can add or remove bits of DNA at the break site in a seemingly random and unpredictable manner. Editing genes with CRISPR-Cas9 allows scientists to break DNA at specific locations, but this can create "spelling errors" that alter the function of genes.
This response to CRISPR-induced damage, called "end joining," is useful for disabling a gene, but researchers have deemed it too error-prone to exploit for therapeutic purposes.
A new study upends this view. By creating a machine-learning algorithm that predicts how human and mouse cells respond to CRISPR-induced breaks in DNA, a team of researchers discovered that cells often repair broken genes in ways that are precise and predictable, sometimes even returning mutated genes back to their healthy version. In addition, the researchers put this predictive power to the test and successfully corrected mutations in cells taken from patients with one of two rare genetic disorders.
The work suggests that the cell's genetic auto-correction could one day be combined with CRISPR-based therapies that correct gene mutations by simply cutting DNA precisely and allowing the cell to naturally heal the damage.To read more, click here.