Nicole Gaudelli invented a way to potentially correct almost half of all genetic diseases caused by single-gene mutations.

Gene-editing tools such as CRISPR can fix some of the single-letter genetic “spelling” mistakes that can drive inherited diseases. But they don’t correct for having the nucleic acid adenine, or A, appear in a DNA strand where there should have been a guanine, or G. This misplaced A is involved in sickle cell disease, cystic fibrosis, Parkinson’s, Alzheimer’s, and many types of cancer.

So Gaudelli set out to make a new enzyme that can cleanly convert A-T base pairs into G-C base pairs with few undesired effects.

“It was a little bit of magic,” says Gaudelli, about getting her enzyme to work. She’s now a senior scientist at Beam Therapeutics, a biotech company based in Cambridge, Massachusetts, working to commercialize her approach.