Scientists edit disease-causing gene mutation in human embryos

Scientists edit disease-causing gene mutation in human embryos

Scientists edit disease-causing gene mutation in human embryos

But the scientists say they're confident they can push that number much higher.

Another remarkable finding was the way the repairs to the embryos' faulty DNA took place.

In addition, the researchers discovered a technical advance that may limit the production of patchwork embryos that aren't fully edited.

Hypertrophic cardiomyopathy, the disease caused by the genetic mutation that Mitalipov and his colleagues successfully edited out of the human embryos, affects about 1 in every 500 people and involves a thickening of the heart muscle that makes it harder for the heart to pump blood. If even one cell in an early embryo is unedited, "that's going to screw up the whole process", says Mitalipov.

The work conducted by these researchers was well within the guidelines set by the National Academies of Sciences, Engineering, and Medicine on the use of CRISPR to edit human genes. Once the embryos were five days old, the team stopped their growth and checked to see how well their approach had wiped out the mutant gene.

Medical ethicist Jeffrey Botkin, M.D., M.P.H. is available to comment on the ethics of editing genes with CRISPR in human embryos. Sometimes eggs had already copied DNA, and a mutant gene escaped editing (top, middle).

However, permitting edits to germ line cells - such as embryos, eggs, and sperm - could also be "very unsafe on multiple levels", DiCamillo warned. Mosaicism refers to an outcome when not all cells in a multicellular embryo get repaired and some cells still carry a mutation.

An global group of 11 organizations, including the American Society of Human Genetics and Britain's Wellcome Trust, on Wednesday issued a policy statement recommending against genome editing that culminates in human implantation and pregnancy, while supporting publicly funded research into its potential clinical applications. Using such a treatment on humans is illegal in both the USA and the United Kingdom - but some experts expect that law will soon be changed, and that the legal and ethical frameworks need to catch up with the technology.

Campaigners warned however that it might also open the door to "superior designer babies", with genes modified to improve physical appearance, strength or even intelligence.

"If all of this holds up for different genes and is also true when the mutation is inherited from the mother, it will be a major step forward", said Janet Rossant, senior scientist and chief of research emeritus at the Hospital for Sick Children in Toronto. The embryos used in this experiment were created using donated sperm from men with a specific genetic mutation that researchers planned to fix with CRISPR. Doctors can treat symptoms of the condition, but there is no cure.

Several teams in China have already reported using CRISPR-Cas9 to alter disease-related genes in human embryos.

Nature stepped in at this point, by using the egg donor's properly functioning MYBPC3 gene as a template on which to base the fix. It uses this as a template to make the corrections - rather like checking a dictionary when you correct the spelling of word.

Boiled down to its simplest explanation, CRISPR-Cas9 works like a pair of scissors to selectively trim out parts of a genome and replace them with new stretches of DNA. Mitalipov is director of the Center for Embryonic Cell and Gene Therapy at OHSU.

It was mentioned, briefly, in an interview the New York Times had with Dr. Paula Amato, a co-author of the study and a reproductive endocrinologist at OHSU.

The procedure also might work in other genetic diseases caused when a person has one good copy and one mutated copy of a gene, Amato said. In the first round of the experiments, they found that 66.7% of embryos - 36 out of 54 - were normal after being injected with CRIPSR. When performed early enough, at the same time as fertilisation, 42 out of 58 embryos, or 72 per cent, were found to be free of the disease-causing mutation.

None of the tested embryos showed any signs that Cas9 was cutting where it shouldn't be. But it was not revealed about how many embryos were created and edited in the experiments, as per ABC news. This gives parents full control over whether or not their child will carry a disease-associated gene, making it incorrect to think of genome editing in embryos as the only way to prevent genetic disease in kids.

"We need to eradicate these genetic conditions", Urbina said.

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