Baby KJ Muldoon was unfortunately born with a rare condition that caused toxic accumulation of ammonia in his body — a unique genetic disorder. Doctors at the Children’s Hospital of Philadelphia were flummoxed.
Then, one of them thought, ‘Why not try CRISPR?’ — namely the gene editing tool that won its inventors, Emmanuelle Charpentier and Jennifer A Doudna, the Nobel Prize in 2020.
Using CRISPR, the doctors corrected a specific genetic sequence in his genome — and made history. In the words of Dr Rebecca Ahrens-Nicklas of the Children’s Hospital of Philadelphia, as quoted in an article in Nature, the drug they developed “is specific to Muldoon’s genetic sequence and will probably never be used for another person”.
The article quotes Arkasubhra Ghosh, a gene therapy expert at Narayana Nethralaya Eye Hospital in Bengaluru, as saying that the approach taken to help Muldoon is “truly the future of all gene and cell therapies”. But Ahrens-Nicklas is more circumspect, saying, “This is still really early days.”
While CRISPR has been used in various clinical settings, such as treating sickle cell disease or beta-thalassaemia, they often involve editing genes in stem cells outside the body and reintroducing them. In contrast, Muldoon’s treatment involved directly editing his liver cells in vivo, using lipid nanoparticles to deliver the CRISPR components.
It wasn’t easy. An international team of doctors and scientists, financially aided by the US government, developed the treatment in six months.