KJ Muldoon is walking at home ahead of Christmas after being hospitalized last holiday due to his rare genetic disorder, CPS1 deficiency Charlotte Phillipp is a Weekend Writer-Reporter at PEOPLE. She ...

A baby born with a rare and life-threatening genetic disorder has taken his first steps after receiving a groundbreaking, personalized gene editing treatment at Children’s Hospital of Philadelphia. KJ ...

KJ Muldoon received a groundbreaking new treatment earlier this year. The baby saved from a rare disease by a first-ever personalized gene fix has reached a big milestone, taking his first steps ahead ...

PHILADELPHIA (WPVI) -- A miracle baby who was treated with a pioneering gene-therapy at Children's Hospital of Philadelphia has reached a major milestone as he took his first steps. KJ Muldoon was the ...