A baby in the US is among the first people with a rare genetic disorder to be treated with CRISPR, a customised gene-editing therapy that allows scientists to edit DNA.
The baby, known as KJ, was diagnosed soon after his birth with a rare disorder called severe carbamoyl-phosphate synthetase 1 deficiency (CPS1), which is estimated to affect about one in a million babies.
The condition causes ammonia levels in the blood to rise, which can lead to vomiting, hypothermia, lethargy, convulsions, brain swelling, and coma. It kills about half of babies with the condition.
Treatment typically involves having a low-protein diet until the child is old enough for a liver transplant, but that approach also comes with health risks.
KJ began receiving personalised CRISPR treatment when he was around six months old, enabling his doctors to reduce his dependence on medication to keep his ammonia levels low, according to the case study published Thursday in The New England Journal of Medicine.
“While KJ will need to be monitored carefully for the rest of his life, our initial findings are quite promising,” said Dr Rebecca Ahrens-Nicklas, who directs the gene therapy programme at Children’s Hospital of Philadelphia in the US, where the operation took place.
Personalised CRISPR gene editing therapy
CRISPR works by targeting specific sequences in the genome, cutting the DNA precisely at those locations, and then leveraging the cell’s natural repair mechanisms to disable the harmful gene or insert a corrected version. In this case, the therapy targeted a faulty gene in KJ’s liver, cutting the DNA at the exact spot where the error occurred to correct the enzyme.
The procedure’s success means additional patients could eventually be treated with the cutting-edge technology, researchers said.
“While KJ is just one patient, we hope he is the first of many to benefit from a methodology that can be scaled to fit an individual patient’s needs,” Ahrens-Nicklas said in a statement.
Challenges to scale up
KJ’s case is a promising proof of concept, but experts cautioned that efforts to develop CRISPR therapies present several challenges. Technically, delivering a gene-editing therapy to other organs rather than the liver is much more difficult. Developing such treatment is also expensive, with the total cost of the procedure being over €700,000, though that is close to the price of a standard liver transplant, the team told the Associated Press.
Though the procedure helped improve KJ’s quality of life, the research team couldn’t fully assess the potential side effects of the intervention for safety reasons.
Dr Alena Pance, a senior lecturer in genetics at the University of Hertfordshire in the UK who was not involved with the procedure, added that most diseases are the result of diverse mutations in the genes, rather than errors that could be addressed through the precise edits made in CRISPR treatments.
“The [CRISPR] approach is applicable to any disease caused by a single nucleotide change, however more often than not, diseases are caused by a variety of variants so perhaps more general strategies could be more effective than very precise ones,” Pance said in a statement.