Doctors at CHOP and Penn have made medical history by successfully treating a baby’s rare genetic disorder with a custom CRISPR therapy—marking the world’s first personalized gene editing cure for a single patient. (Source: Image by RR)

Custom Gene Editing Offers Hope for Treating Ultra-Rare Diseases

Physicians and researchers at Children’s Hospital of Philadelphia (CHOP) and Penn Medicine have made medical history by successfully treating a baby named KJ with a rare and often fatal metabolic condition using a customized CRISPR-based gene editing therapy. KJ, as noted in interestingengineering.com, was born with carbamoyl phosphate synthetase 1 (CPS1) deficiency, a urea cycle disorder that hinders the body’s ability to eliminate ammonia, leading to potentially lethal buildups. This marks the first time a CRISPR therapy has been tailored specifically to a single patient’s unique genetic mutation, offering a glimpse into the potential for individualized treatments in rare diseases.

CPS1 deficiency traditionally requires highly restrictive diets or liver transplants, both of which are difficult to implement in infants. Instead, researchers led by Dr. Rebecca Ahrens-Nicklas of CHOP and Dr. Kiran Musunuru of Penn developed a personalized gene therapy in just six months. KJ received his first dose in February 2025, followed by additional infusions in March and April. Since treatment, he has shown marked improvement—tolerating more protein, requiring fewer medications, and avoiding dangerous spikes in ammonia during infections.

The success of KJ’s case highlights a new direction for genetic medicine. Rather than focusing solely on common genetic conditions, this bespoke approach demonstrates the feasibility of tailoring treatments for rare, life-threatening mutations. The research team views this case as a scalable model that could be replicated by other institutions to treat similarly rare conditions lacking standard therapies.

While KJ will require lifelong monitoring, his progress suggests that personalized CRISPR treatments may become a powerful tool in modern medicine. This milestone affirms the long-promised potential of gene therapy and may inspire further innovation in how rare genetic diseases are diagnosed and managed—moving the field toward individualized care that offers real hope for patients with no other options.

read more at interestingengineering.com