Personalized CRISPR gene therapy for rare diseases
KJ Muldoon, the first infant treated with personalized CRISPR gene-editing therapy for a rare metabolic disorder, has shown significant improvement as of June 28, 2026, tolerating increased dietary protein and requiring less medication. As of June 28, 2026, KJ is thriving, walking, and talking, with no adverse effects reported one year after treatment. Separately, Daniel Cressy in the Gulf South region has been functionally cured of Sickle Cell Disease after receiving Casgevy, a CRISPR/Cas9 gene therapy. The FDA unveiled draft guidance on February 23, 2026, for a new approval pathway for custom CRISPR therapies, inspired by KJ's successful treatment for CPS1 deficiency. Researchers plan to submit an Investigational New Drug (IND) application in 2026 to initiate a clinical trial for rare diseases.
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June 2026 — 1 developments
KJ Muldoon, the first infant treated with personalized CRISPR gene-editing therapy for a rare metabo…
KJ Muldoon, the first infant treated with personalized CRISPR gene-editing therapy for a rare metabolic disorder, has shown significant improvement, tolerating increased dietary protein and requiring less medication. Separately, Daniel Cressy in the Gulf South region has been functionally cured of Sickle Cell Disease after receiving Casgevy, a CRISPR/Cas9 gene therapy.
April 2026 — 2 developments
Drs. Kiran Musunuru and Rebecca Ahrens-Nicklas were recognized among TIME's 100 Most Influential Peo…
Drs. Kiran Musunuru and Rebecca Ahrens-Nicklas were recognized among TIME's 100 Most Influential People of 2026 for their pioneering work on personalized CRISPR gene therapy for CPS1 deficiency. This therapy, developed for infant KJ Muldoon, represents a historic milestone in treating rare genetic diseases.
The research team behind KJ's personalized CRISPR gene therapy plans to submit an Investigational New Drug (IND) application in 2026 to initiate a clinical trial for rare diseases.
The research team behind KJ's personalized CRISPR gene therapy plans to submit an Investigational New Drug (IND) application in 2026 to initiate a clinical trial for rare diseases. This follows the one-year anniversary of KJ's successful treatment for CPS1 deficiency.
February 2026 — 3 developments
KJ, the first infant to receive personalized CRISPR gene therapy for CPS1 deficiency, has marked the one-year anniversary of his treatment.
KJ, the first infant to receive personalized CRISPR gene therapy for CPS1 deficiency, has marked the one-year anniversary of his treatment. He is now thriving, walking, and talking, showing significant clinical improvements with no adverse effects. The Children's Hospital of Philadelphia is looking to expand this treatment to other rare diseases.
The FDA has unveiled draft guidance for a new approval pathway for custom CRISPR therapies, inspired by the successful treatment of infant KJ for CPS1 deficiency.
The FDA has unveiled draft guidance for a new approval pathway for custom CRISPR therapies, inspired by the successful treatment of infant KJ for CPS1 deficiency. This pathway aims to speed the development of bespoke treatments for rare diseases, potentially allowing data from a few patients to support approvals for broader populations.
As of today, KJ continues to thrive, showing no adverse effects from the treatment, growing well, an…
As of today, KJ continues to thrive, showing no adverse effects from the treatment, growing well, and meeting developmental milestones, though ongoing monitoring is planned for his lifetime.
October 2025 — 1 developments
Researchers behind the personalized CRISPR therapy for Baby KJ are planning to launch a new type of …
Researchers behind the personalized CRISPR therapy for Baby KJ are planning to launch a new type of clinical trial specifically for rare diseases to make advanced gene-editing technologies more accessible.
August 2025 — 1 developments
Further analysis and reports continue to affirm the early success of the personalized CRISPR base-ed…
Further analysis and reports continue to affirm the early success of the personalized CRISPR base-editing in treating CPS1 deficiency, underscoring its significance for genomic medicine.
July 2025 — 1 developments
The Chan Zuckerberg Initiative and the Innovative Genomics Institute launched a new $20 million Cent…
The Chan Zuckerberg Initiative and the Innovative Genomics Institute launched a new $20 million Center for Pediatric CRISPR Cures in July 2025, building on the success of KJ Muldoon's case.
June 2025 — 1 developments
KJ Muldoon, the infant who received the world's first personalized CRISPR-based gene editing therapy, was released from the hospital after more than 300 days.
KJ Muldoon, the infant who received the world's first personalized CRISPR-based gene editing therapy, was released from the hospital after more than 300 days.
May 2025 — 5 developments
News outlets widely report on the medical breakthrough, emphasizing the potential for personalized gene editing to treat other ultra-rare genetic diseases.
News outlets widely report on the medical breakthrough, emphasizing the potential for personalized gene editing to treat other ultra-rare genetic diseases.
Researchers from the Innovative Genomics Institute (IGI) at UC Berkeley, in collaboration with Penn …
Researchers from the Innovative Genomics Institute (IGI) at UC Berkeley, in collaboration with Penn Medicine and the Children's Hospital of Philadelphia (CHOP), developed and administered the first on-demand CRISPR therapy for an infant named KJ. This personalized in vivo CRISPR therapy was developed and delivered to KJ in just six months, a process that has been fast-tracked for approval by the FDA. KJ was born with carbamoyl phosphate synthetase 1 (CPS1) deficiency, an ultra-rare disease affecting approximately 1 in 1.3 million newborns.
KJ Muldoon, the first infant to receive a personalized CRISPR gene editing therapy for CPS1 deficiency, has been successfully treated.
KJ Muldoon, the first infant to receive a personalized CRISPR gene editing therapy for CPS1 deficiency, has been successfully treated. The therapy was administered between February and April 2025, and the child is reportedly doing well, showing no adverse effects and meeting developmental milestones. This marks a significant breakthrough in genomic medicine for rare diseases.
The research team presents KJ's case at the American Society of Gene & Cell Therapy Annual Meeting, …
The research team presents KJ's case at the American Society of Gene & Cell Therapy Annual Meeting, highlighting the rapid development and administration of the personalized therapy.
The groundbreaking case study detailing KJ's successful treatment and initial outcomes is published in The New England Journal of Medicine.
The groundbreaking case study detailing KJ's successful treatment and initial outcomes is published in The New England Journal of Medicine.
April 2025 — 1 developments
KJ receives a third infusion of the personalized CRISPR therapy to further enhance the treatment's efficacy.
KJ receives a third infusion of the personalized CRISPR therapy to further enhance the treatment's efficacy.
March 2025 — 2 developments
Early results show significant improvement in KJ's condition, allowing him to tolerate increased protein intake and reduce his reliance on ammonia-lowering medications.
Early results show significant improvement in KJ's condition, allowing him to tolerate increased protein intake and reduce his reliance on ammonia-lowering medications.
KJ receives a second infusion of the personalized CRISPR therapy as part of the ongoing treatment protocol.
KJ receives a second infusion of the personalized CRISPR therapy as part of the ongoing treatment protocol.
February 2025 — 1 developments
At approximately six months of age, KJ receives the first infusion of his customized CRISPR base-edi…
At approximately six months of age, KJ receives the first infusion of his customized CRISPR base-editing therapy, marking the world's first administration of such a personalized treatment.
September 2024 — 1 developments
Following the failure of conventional treatments and consideration of a liver transplant, a team at …
Following the failure of conventional treatments and consideration of a liver transplant, a team at Children's Hospital of Philadelphia (CHOP) and Penn Medicine begins developing a personalized CRISPR base-editing therapy specifically for KJ.