For the first time in medical time, doctors in the United States have administered a personalized gene treatment to the treatment of a rare and deadly genetic disorder, paving the way for new, targeted treatments that “re -register” DNA shortly after birth.

Researchers internationally welcomed the achievement as a medical milestone, stressing that it shows the potential of the treatment of a series of genetic diseases through the repair of defective DNA.

Experts at the Philadelphia Pediatric Hospital and the University of Pennsylvania immediately started procedures after the child was diagnosed, completing the design, production and safety tests of personalized treatment within six months.

The infant, known as the original KJ, received the first dose of specially designed intravenous infusion treatment in February and two more doses in March and April. Doctors said the child responds well and develops smoothly, but will need lifelong close monitoring.

Dr. Rebecca Arenz-Niklas, a team’s leading physician, said this medical progress was made possible by “years and years of progress” in gene processing technology. “Although KJ is only one patient, we hope he will be the first of many to benefit,” he said.

KJ was born with severe CPS1 deficiency, an extremely rare condition affecting about 1 in 1.3 million people. People with this condition are deprived of a liver enzyme that converts ammonia, a product of natural breakdown of proteins in the body, into urea to eliminate through urine. Inability to eliminate blood ammonia ammonia, which can cause severe liver damage and other organs, such as the brain.

Although in some cases liver transplantation, infants with severe form of the disease have already suffered significant damage until they reach an appropriate age for surgery.

In their publication in the New England Journal of Medicine, doctors described in detail the exhaustive process of identifying the specific mutations responsible for KJ disorder, the design of gene therapy for their correction and the tests of both the treatment and lipid nanosomes. Treatment is based on a powerful technique called Base Editing, which allows the “Letter to Letter” genetic code to be rewritten.

KJ spent the first months of his life in the hospital, following a strict diet. Since the treatment began, doctors have managed to increase the amount of protein in his diet and reduce the medication needed to remove nitrogen from his body. The findings were presented at the annual conference of the American Society of Genetic and Cell therapy in New Orleans.

The medical team noted that long -term monitoring is needed to assess the effectiveness of treatment, but early signs are encouraging.

“The promise of gene therapy we have been listening to for decades, is beginning to be implemented and is going to radically change the way we approach medicine,” said Professor Kiran Mousunourou of the University of Pennsylvania.

Geneticist Dr. Miguel Angel Moreno-Mateus of the University of Pablo de Olavide in Seville commented: “Although it is a highly targeted approach, partly because of the rarity and severeness of the disease, it is a landmark that proves that these treatments are now reality. As stated in the article, the patient will be monitored for a long time to ensure his well -being and assess if additional doses are required to further improve symptoms. “