Summary: Scientists in a bold attempt have tried gene editing inside a human body for the first time to permanently change a person’s DNA to cure the disease.
In a bold attempt, scientists have tried gene editing (a type of genetic engineering in which DNA is inserted, deleted or replaced in the genome) in a person with a metabolic disease called Hunter syndrome. The experiment was done on a 44-year-old Brian Madeux, through an IV he was given billions of copies of a corrective gene and a genetic tool to cut his DNA in a precise spot. Scientists say that it takes around 3 months to know how the therapy is working. If the therapy is a success it could give a major boost to the emerging field of gene therapy. This kind of gene editing treatment can be used to treat only a few types of diseases. Some give results which may not last long and some others insert the new gene in the incorrect part of the genome causing a new issue such as cancer.
Before testing on a human this therapy was tested in animals and said to have promising results. The team says that so far there is no evidence that this kind of genetic manipulation will be dangerous. In the treatment that Madeux is receiving, the new gene will be placed in the precise location as like sending a mini surgeon along with it. The inserted new gene becomes the part of the DNA for the rest of life with invisible mending, which means there’s no going back and erase any mistakes done by the gene editing.
Worldwide there are less than 10,000 people suffering from these metabolic diseases because many die very young. In Madeux’s condition, Hunter syndrome lacks a gene which produces an enzyme that helps in breaking certain carbohydrates. These build up and create a havoc inside the body. The common symptoms observed are frequent colds and ear infections, trouble in breathing, skin and eye problems, bone and joint flaws, bowel issues, brain and cognitive problems. Weekly IV doses of the missing enzyme can lessen some symptoms but it costs between $100,000 and $400,000 per year.
Instead of CRISPR (a gene editing tool which has got lot recent attention), in this study, scientists used a different one called zinc finger nucleases. The therapy has three parts – The new gene and two zinc finger nucleases. DNA instructions for parts are placed in a virus (altered no to cause infection) and billions of copies of these given through a vein. They travel to the liver – make zinc fingers and prepare the corrective gene. The zinc fingers the DNA, allows the new gene to slip in. Then the new gene directs the cell to make the enzyme required by the patient.
The patient, Brian Madeux said, “It’s kind of humbling” to be the first to test this, I’m willing to take that risk. Hopefully, it will help me and other people.” “I’ve been waiting for this my whole life, something that can potentially cure me.”
Hank Greely, Stanford University bioethicist said, “When you stick a chunk of DNA in randomly, sometimes it works well, sometimes it does nothing and sometimes it causes harm”, “The advantage with gene editing is you can put the gene in where you want it.”