The disease had warped his airway. Mr Madeux has a chef's degree and was part owner of two restaurants in Utah, cooking for US ski teams and celebrities, but now can't work in a kitchen or ride horses as he used to. Gene editing won't fix damage he's already suffered, but he hopes it will stop the need for weekly enzyme treatments.
Initial studies will involve up to 30 adults to test safety, but the ultimate goal is to treat children very young, before much damage occurs. A gene-editing tool called CRISPR has gotten a lot of recent attention, but this study used a different one called zinc finger nucleases. They're like molecular scissors that seek and cut a specific piece of DNA. The therapy has three parts: The new gene and two zinc finger proteins. DNA instructions for each part are placed in a virus that's been altered to not cause infection but to ferry them into cells.
Billions of copies of these are given through a vein. They travel to the liver, where cells use the instructions to make the zinc fingers and prepare the corrective gene. The fingers cut the DNA, allowing the new gene to slip in. The new gene then directs the cell to make the enzyme the patient lacked. However, there are some situations in which rare mutations can spread widely, whether they're useful or not. Take Huntington's disease, a harrowing condition which gradually stops the brain working normally, eventually causing death.
It's unusual for a genetic disease in that even if you have one healthy copy of the gene you will still develop it — meaning that you might expect it to eventually die out. However, at Lake Maracaibo in northwest Venezuela — actually vast, ancient inlet of the Caribbean Sea — there is a higher concentration of people with the disease than anywhere else in the world.
There are two reasons that this is thought to have happened. One is the fact that Huntington's disease typically materialises when people are around 40 years old, which is after the age at which most people have children — and consequently, the illness is almost invisible to evolution , which primarily cares if an organism has survived to the age of reproduction. The second is the Founder Effect , which distorts the distribution of genes in small populations by allowing the unusual genes of the "founders" — early community members — to propagate more widely than they otherwise would.
She was a carrier of the deadly mutation that causes it, which she passed on to more than 10 generations of descendants — encompassing more than 14, living people , as of The Founder Effect can distort the frequency of genes in a population, and is thought to have led to the high prevalence of Huntington's at Lake Maracaibo Credit: Getty Images.
In China where it's thought they live, there are currently high rates of internal migration , so it's conceivably less likely that the genes will become embedded.
Another possibility is that the genetic mistakes will be located next to a highly beneficial trait on the genome, so that they're inherited together — a situation that allows neutral or harmful mutations to piggyback their way to a higher prevalence than they deserve.
However, Saha points out that it may take many, many generations for any patterns in the distribution of genetic errors to materialise. This is a very big question for us to collectively think about. There is an obvious solution — though there's no guarantee edited humans would agree to it, and it relies on a person being aware that their reproductive cells have been edited, as may not be the case with those who have undergone somatic editing for an illness that manifests elsewhere in the body.
Rather than allowing any artificial mutations to propagate, we could simply correct them, using the same technique that was used to create them in the first place. Given the how little we know about the functions of certain genes in our current environment, Saha believes we must be extra cautious when making potentially millennia-straddling changes.
To decide if an edit is ethical, we might first need to understand what kind of future world it could linger on in. An earlier version incorrectly referred to He Jiankui by his first name.
The article also described the Huntington's mutation as recessive, when it is dominant. Join one million Future fans by liking us on Facebook , or follow us on Twitter or Instagram.
If you liked this story, sign up for the weekly bbc. The genetic mistakes that could shape our species. Share using Email. By Zaria Gorvett. New technologies may have already introduced genetic errors to the human gene pool. How long will they last? And how could they affect us?
He Jiankui seemed nervous. As well as misunderstandings about the differences between mRNA and DNA, there are some biological entities which do change DNA, including treatments for some genetic diseases and even some viruses, which can have devastating effects on our DNA. Some viruses do change DNA and this can have extremely negative consequences. Because they are often indiscriminate as to where in the genome they put themselves, if they end up in the middle of a piece of code that is crucial for the cell, they can cause the cell to become cancerous.
HPV can cause several different cancer types, including cervical and head and neck, which is why people are now often vaccinated against HPV. Another example is HIV, which integrates its own genome into that of human white blood cells, forcing the cell to make many copies of the virus, which eventually burst out to infect other cells. Some treatments do intentionally change DNA, with intended positive consequences. Scientists are increasingly trying to tackle genetic diseases by using gene therapies to correct, often inherited defects in DNA.
New treatments for life-threatening or disabling conditions are now being approved at an impressive rate. In , the FDA approved a virus-based drug to correct a genetic defect which causes blindness and others are in development for hearing loss and several other types of genetic disease. But historically, gene therapy using viruses has had a rough ride. If it is effective at restoring vision for subjects in the trial, the next step would be Phase 3 trials to see if it is possible to have it approved as something that can be performed on the public to treat this condition.
Patients with this particular type of retinal dystrophy may be able to see a day when treatment will be possible to prevent, halt, or reverse blindness for them, and for their children, as well.
Altering the DNA means that it stops it in its tracks and prevents it from replicating in future generations. What is even more exciting is the roadmap this could lay for future gene therapies. Casey Ophthalmic Genetics Division, said in a statement that the importance of this first use of CRISPR in vivo is that it could have potential to be used beyond ophthalmology.
The excitement over the potential often outweighs the human risk that goes into making it safe for the general public. We need to recognize how brave they are and how valuable their contributions are. The success of a Mississippi woman's treatment for sickle cell disease provides hope that gene editing could help treat the ailment.
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