It affects how we understand ourselves as humans and what kind of future we want to build. It has implications for society as a whole , not just individuals. Therefore, decisions about whether to permit germline modification should not be made by small groups of scientists or bioethicists, by biotechnology companies, or by wealthy elites.
Human germline editing is an urgent social justice issue; we need public discussions of it that are open to all. These labs were deciphering the secrets of embryos and had a particular interest in how eggs are formed. Surgeons in New York have successfully attached a kidney grown in a genetically altered pig to a human patient and found that the organ worked normally, a scientific breakthrough that one day may yield a vast new supply of organs Many describe the move from bench to bedside from basic science to therapeutic or preventive applications as a sprint — a short quick race.
Others suggest that the race such as it is is more like hurdles given the many Main navigation. Search Search Donate Subscribe. What is Human Gene Editing? Gene Therapy: Changing genomes to treat disease There are two distinct ways gene editing might be used in humans.
Germline Editing: Changing the genomes of future generations But there is a much more controversial way that human gene editing could be used. Understanding the Social and Ethical Risks New technologies often raise ethical questions about their unknown risks and benefits.
Who Gets to Decide? Related Articles. How Silicon Valley hatched a plan to turn blood into human eggs. Aggregated News. Animal Biotechnologies. Mythmakers in the Market for Perfection. By Sheila Jasanoff, American Scientist Human Genetic Modification. Heritable human genome editing: Who decides?
The gene damaged in cystic fibrosis contains about , base pairs, while the one that is mutated in muscular dystrophy has about 2. Each of us inherits about 60 new mutations from our parents, the majority coming from our father. But how do you get to the right cells? This is the big challenge. Most drugs are small molecules that can be ferried around the body in the bloodstream and delivered to organs and tissues on the way. The gene editing molecules are huge by comparison and have trouble getting into cells.
But it can be done. One way is to pack the gene editing molecules into harmless viruses that infect particular types of cell. Millions of these are then injected into the bloodstream or directly into affected tissues. Once in the body, the viruses invade the target cells and release the gene editing molecules to do their work. In , scientists in Texas used this approach to treat Duchenne muscular dystrophy in mice. The next step is a clinical trial in humans.
Viruses are not the only way to do this, though. Researchers have used fatty nanoparticles to carry Crispr-Cas9 molecules to the liver, and tiny zaps of electricity to open pores in embryos through which gene editing molecules can enter. Does it have to be done in the body? When the virus enters the body, it infects and kills immune cells. But to infect the cells in the first place, HIV must first latch on to specific proteins on the surface of the immune cells.
Without the proteins, the HIV virus can no longer gain entry to the cells. Having edited the cells to make them cancer-killers, scientists grow masses of them in the lab and infuse them back into the patient.
The beauty of modifying cells outside the body is that they can be checked before they are put back to ensure the editing process has not gone awry. What can go wrong? Modern gene editing is quite precise but it is not perfect. The procedure can be a bit hit and miss, reaching some cells but not others. Even when Crispr gets where it is needed, the edits can differ from cell to cell, for example mending two copies of a mutated gene in one cell, but only one copy in another.
For some genetic diseases this may not matter, but it may if a single mutated gene causes the disorder. Another common problem happens when edits are made at the wrong place in the genome. Will it lead to designer babies? The overwhelming effort in medicine is aimed at mending faulty genes in children and adults.
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. Only 1 per cent of liver cells would have to be corrected to successfully treat the disease, said Mr Madeux's physician and study leader, Dr Paul Harmatz at the Oakland hospital.
We're just learning," but safety tests have been very good, said Dr Carl June, a University of Pennsylvania scientist who has done other gene therapy work but was not involved in this study. Safety issues plagued some earlier gene therapies. One worry is that the virus might provoke an immune system attack. In , year-old Jesse Gelsinger died in a gene therapy study from that problem, but the new studies use a different virus that's proved much safer in other experiments.
Another worry is that inserting a new gene might have unforeseen effects on other genes. Several patients later developed leukaemia because the new gene inserted into a place in the native DNA where it unintentionally activated a cancer gene.
Finally, some fear that the virus could get into other places like the heart, or eggs and sperm where it could affect future generations. Doctors say built-in genetic safeguards prevent the therapy from working anywhere but the liver, like a seed that only germinates in certain conditions.
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