CHOP, Penn doctors behind lifesaving gene-editing therapy named TIME's 100 Most Influential People of 2026
A pair of Philadelphia doctors behind the groundbreaking and lifesaving treatment of a baby boy from Delaware County, Pennsylvania, were named among TIME's 100 Most Influential People of 2026.
Dr. Kiran Musunuru and Dr. Rebecca Ahrens-Nicklas were included on the list for their pioneering work with CRISPR gene-editing therapy, which helped save the life of KJ Muldoon.
KJ was born with a rare and life-threatening urea cycle disorder, which caused ammonia build-up in his body.
"In patients who have urea cycle disorders, they can't break down protein, and unfortunately, what happens is ammonia builds up, and ammonia can be toxic to the brain and cause permanent neurologic damage," said Dr. Rebecca Ahrens-Nicklas, of CHOP.
Dr. Ahrens-Nicklas and Dr. Musunuru, of Penn, led a team from the two hospitals that used CRISPR gene editing to identify and edit out KJ's defective DNA and replace it with an altered, repaired sequence.
After more than 300 days in the hospital, KJ's condition improved so significantly that he was able to go home in June 2025.
"This achievement goes beyond one child. Musunuru and Ahrens-Nicklas brought together innovations from across biomedical science and proved that on-demand CRISPR therapies can be developed safely and quickly enough to help patients who don't have years to wait," Nobel Prize-winning biochemist Jennifer Doudna wrote for TIME. "A decade from now, their names will be in medical textbooks, not only for baby KJ, but for opening the door to personalized genetic medicine for thousands of children after him."
Doudna co-discovered CRISPR-Cas9 gene-editing technology.
In February, the Muldoon family and CHOP doctors took KJ's story to Capitol Hill, where they spoke with lawmakers and advocated for pediatric research funding that could expand access to personalized gene therapies to more families of sick children.
"We have made it our mission to figure out ways of being able to scale this so that more rare disease patients have access to this transformational technology," Dr. Ahrens-Nicklas said.
