The baby who was treated, Kyle “KJ” Muldoon Jr., suffers from a rare metabolic condition caused by a particularly unusual gene misspelling.
Researchers say their attempt to correct the error demonstrates the high level of precision new types of gene editors offer.
“I don’t think I’m exaggerating when I say that this is the future of medicine,” says Kiran Musunuru, an expert in gene editing at the University of Pennsylvania whose team designed the drug. “My hope is that someday no rare disease patients will die prematurely from misspellings in their genes, because we’ll be able to correct them.”
The project also highlights what some experts are calling a growing crisis in gene-editing technology. That’s because even though the technology could cure thousands of genetic conditions, most are so rare that companies could never recoup the costs of developing a treatment for them.
In KJ’s case, the treatment was programmed to correct a single letter of DNA in his cells.
“In reality, this drug will probably never be used again,” says Rebecca Ahrens-Nicklas, a physician at the Children’s Hospital of Philadelphia who treats metabolic diseases in children and who led the overall effort to treat the child.
That effort involved more than 45 scientists and doctors as well as pro bono assistance from several biotechnology companies. Musunuru says he cannot estimate how much it had cost in time and effort.
Eventually, he says, the cost of custom gene-editing treatments might be similar to that of liver transplants, which is around $800,000, not including lifelong medical care and drugs.
