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Scientists might be able to repair a defective DNA in a father's sperm even before fertilizing an egg, according to a new study presented this week.
CRISPR gene editing technology has shown promise for extracting the wrong DNA and replacing it with embryos, but as their cells multiply, DNA is fixed can enter some cells and not in others.
Changing the genetic makeup of sperm would solve this problem but, until now, scientists have struggled to find a way to edit them genetically without killing them.
But scientists at Weill Cornell Medicine in New York think they may have found a way: by delivering an electrical impulse to the sperm, breaking their outer casing and allowing them to deliver CRISPR to the cell .
The gene editing using the CRISPR-Cas9 system has been hailed as one of the greatest innovations of medicine in recent decades.
If perfected, it could "repair" just about any genetic mutation that encodes for birth defects and inherited medical disorders even before a child's birth.
Scientists have tried the method in experiments on human embryos, but it is too early to know if it is still safe.
Embryonic development is a stage of rapid cell multiplication. It's unclear when – or even if – CRISPR can be used to change everything and not just a part of the embryo's DNA.
If some cells receive DNA repaired, but others receive defective DNA, the result could be a genetic mosaicism, in which a person presents with features of a disorder in some parts of his body but not in others.
Although CRISPR is very accurate, it is difficult to anticipate what secondary genetic disturbances it might cause.
The United States has long had both medical and ethical concerns regarding the use of the system in human embryos.
Some people worry that CRISPR is an important step in the direction of manufacturing "branded babies" and the National Institutes of Health (NIH) have banned its use on human embryos.
Controversial, the committees of the National Academy of Medicine and the National Academy of Sciences have both given the go-ahead to genetically alter human embryos when no other treatment for disorders that is not available. they were wearing.
But reproductive cells – sperm and eggs – present fewer medical and ethical barriers to scientists, so changing the DNA that they carry could bypass certain limitations in the world. use of powerful technology of genetic publishing in the future.
More than 10,000 genetic diseases are "one gene" diseases, which means that they are transmitted to their offspring by a mutation in a single part of the DNA from one or the other parent, carried by their sperm or their egg.
Thus, "in theory, all monogenic human-transmissible disorders can be treated if we are able to use CRISPR-Cas9 successfully on sperm," said Dr. Diane Choi, Senior Scientist at New Scientist.
These disorders include sickle cell anemia, cystic fibrosis and muscular dystrophy.
The problem is that scientists need to adopt a kind of Goldilocks approach for gene editing sperm.
A sperm has a hard exterior that allows it to penetrate into an egg, but it is also sensitive and can die if it is subjected to too much stress.
Weill Cornell researchers had to find just the right pulse rate to use on the sperm to disarm his outer shield enough to insert CRISPR-Cas9 without crippling his ability to move.
They experimented with a range of very high voltage shocks delivered in very short bursts and found that the optimum pulse was 20 milliseconds from 1100 volts – almost 100 times the power of a car battery , dynamited with sperm for one fiftieth of one second.
Shocking CRISPR in sperm reduced their motility – or their ability to swim to an egg to fertilize it – dramatically enough, but it also knocked out defective genes, according to the new study, presented at the Society's annual meeting European Union of Human Reproduction and Embryology.
It's still a work in progress, but this latest research suggests that if the strongest and fastest sperm are treated with the CRISPR gene, they could carry a DNA corrected to an egg, allowing a embryo to develop or impaired by bioengineering.
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