The goal is to treat unborn children as early as possible, before their disease causes irreversible damage. But the ambition is to do so without heritable DNA changes, that is, by targeting only somatic tissues and avoiding sex cells. Fetal genome editing, then, differs from embryo editing, which has raised so much controversy in recent years. The best way to understand how far it has come and how much remains to be done is to tell the story of the scientist most committed to this challenge. The opportunity is provided by a longread published in STAT, where Tippi MacKenzie’s biography is interwoven with a review of the field.

Fetal surgery represents one of the most exclusive clubs in medicine, to borrow Megan Molteni’s words. Suffice it to say that about 300,000 surgeons practice in the U.S., but only about 100 operate on unborn patients. You can say that the discipline has came into the world in the early 1980s at the University of California Children’s Hospital based in San Francisco, with the first surgeries performed by Michael Harrison to correct malformations directly in the womb.

The cradle of CRISPR is not far from there, in Berkeley, where Jennifer Doudna made the experiment of her life. Today, bringing the two ideas together is the challenge of fetal genome surgery, whose center of gravity may be located right in San Francisco, at the Center for Maternal-Fetal Precision Medicine. At the forefront is a Turkish-born woman who came to the U.S. at age 11 with her parents (her father was a professor of computer science, her mother an English teacher). Tippi – who was born Cicek and became MacKenzie after marriage – seemed destined to become a professional pianist, but preferred a future in the science of advanced therapies.

It was she who launched the first stem cell transplant in a fetus in 2017, for a severe form of thalassemia. MacKenzie is also involved in a pioneering trial aiming to provide unborn children with a rare disease (mucopolysaccharidosis) with a life-saving enzyme. The surgeon-scientist has also a long-standing interest in gene therapy and is currently busy discovering how to prevent fetal editing from inadvertently altering the germline. Please find out more about her work in the STAT article.