A 23-year-old man from Louisiana has become one of the first people in the United States to be functionally cured of sickle cell disease using Casgevy, the first approved CRISPR-based gene editing therapy.
Daniel Cressy, from Metairie near New Orleans, had suffered from the genetic blood disorder since childhood, suffering from severe pain crises and frequent hospitalizations. After undergoing pioneering treatment at Manning Family Children’s Hospital, doctors confirmed that he no longer showed signs of active sickle cell disease. His case represents the first successful use of Casgevy in Louisiana and the Gulf South, highlighting a major milestone in the use of gene editing technology to treat inherited disorders.
How the first world CRISPR therapy
Casgevy became the first CRISPR-based gene-editing therapy to receive regulatory approval in late 2023. Unlike traditional treatments that focus on managing symptoms, Casgevy targets the underlying cause of sickle cell disease using the patient’s hematopoietic stem cells. Doctors first collect these stem cells and send them to a specialized laboratory, where scientists use CRISPR-Cas9 technology to edit the cells outside the body.
Instead of directly repairing the defective hemoglobin gene, the treatment reactivates fetal hemoglobin production, preventing red blood cells from becoming sickle-shaped.Chrissie’s stem cells were collected in late 2025 and sent to Scotland for gene editing. In March 2026, the modified cells were returned to New Orleans after he underwent chemotherapy to make room in his bone marrow. Doctors injected the modified cells on March 18, allowing her to start producing healthy red blood cells.
After spending about a month recovering in hospital, Chrissy was released from the hospital in mid-April. After about 100 days of treatment, doctors confirmed that his hemoglobin levels were normal and that there was no active sickle cell disease.
He celebrated the milestone by ringing the ceremonial hospital bell, calling it his “second birthday.”
What is sickle cell disease?
Sickle cell disease is a genetic blood disorder caused by a mutation in the HBB gene, which produces hemoglobin, the protein that carries oxygen through the body.
The mutation causes red blood cells to become rigid and crescent-shaped instead of round and flexible. These abnormal cells can block blood vessels, leading to severe pain, strokes, organ damage, and other life-threatening complications. The disease affects about 100,000 people in the United States and millions more around the world, especially those of African descent.
Why Casgevy is different from a bone marrow transplant
For decades, the only potential cure for sickle cell disease was a bone marrow transplant from a closely matched donor.
However, many patients never find a suitable donor, and the procedure carries a risk of graft-versus-host disease. Casgevy avoids these challenges because it uses the patient’s own stem cells. Although patients still need extensive chemotherapy before receiving the modified cells, using their own cells significantly reduces the risk of immune rejection.
A milestone in genetic medicine
Casgevy was jointly developed by Vertex Pharmaceuticals and CRISPR Therapeutics and was approved by the FDA in December 2023 for eligible patients ages 12 and older with recurrent sickle cell pain crises.
Danielle Cressey’s recovery shows how CRISPR has moved from laboratory research into routine clinical care. While doctors continue to monitor patients long-term, his case provides new hope that gene editing could transform the treatment of inherited genetic disorders and improve the lives of thousands of people with sickle cell disease.Before treatment, Chrissy’s dream of becoming a commercial pilot seemed out of reach due to his medical condition. Now, with no active signs of sickle cell disease, he hopes to pursue flight training and obtain the medical certification necessary to fly professionally. His recovery has become a powerful example of how advances in gene editing medicine can offer new possibilities for patients who were once limited by genetic diseases.