Scientist replacing bits of DNA

DNA Editing in Human Embryos

Scientists are getting closer to perfecting DNA editing in human embryos, increasing the ability to snip out inherited genetic diseases from human offspring. For decades, scientists have been tinkering with the DNA of humans as well as other living things. Previous attempts by Chinese researchers proved unsuccessful because of some safety concerns. These studies, open the possibility of preventing the transfer of genetic diseases from one generation to another, raised red flags and were initially shut down. It’s a bold idea, that is finally reaching the point where it can be put into action.

When the procedure becomes established and accepted, people with genetic diseases can opt to reproduce through IVF in order for the embryos to be screened for harmful mutations.

Recently, a team of international scientists were able to successfully modify human embryos, removing the genetic mutations responsible for sudden cardiac arrest in healthy individuals. It was said to be a safe and acceptable demonstration of advanced technology for this complicated procedure.

This is the first case of genome editing in human embryos performed outside of China. The research focused on a genetic form of heart disease, which scientists believe could be used for different conditions that are caused by a single gene mutation; including some types of breast cancer and cystic fibrosis.

Scientists hope that if the embryo gene correction method can be proven to be a safe procedure, it can potentially be used to eradicate genetic diseases that have passed on through generations.

The procedure of modifying human embryos to remove genetic mutations utilizes the CRISPR-Cas9, a powerful gene-editing tool. It can fix mutations within embryos produced from the sperm of a man who inherited hypertrophic cardiomyopathy. A heart condition that leads to the thickening of the muscular wall of the heart, affecting one in 500 individuals, and is the common cause of sudden cardiac arrests among young people.

DNA Editing Corrects Life Threatening Defects

Every human gene has two copies. Some diseases are the result of the mutation in one copy of the gene. For this particular study, a man who carries a single mutant copy of the MYBPC3 gene, which causes hypertrophic cardiomyopathy, was recruited.

Using the man’s sperm and healthy eggs from some donors, the scientists found that about 50% of the embryos had the inherited mutant gene. If the embryos were to be implanted into women scheduled to carry them to full term, the offspring would inherit the heart condition of the father.

gene editing diagram

Gene editing significantly reduced the number of embryos that continued to carry the dangerous mutation. When gene editing was performed at the time of fertilization, 72% of the embryos were found to be free of the disease-causing mutation.

The result of the demonstration proved to be impressive due to previous attempts at gene editing only partially working, preventing mutations in a few cells but not in the rest. Previous gene editing procedures also resulted in the accidental targeting of wrong genes during the modification process. This latest demonstration of gene editing did not show any off target effects.

Richard Hynes, a geneticist at MIT claimed “They’ve got remarkably good results,” bringing the study “closer to clinics, but there’s still a lot of work to do.” When the procedure becomes established and accepted, people with genetic diseases can opt to reproduce through IVF in order for the embryos to be screened for harmful mutations. Gene editing could increase the number of healthy embryos that will be available for a doctor to implant.

There will be more work ahead in order to prove that gene editing is safe. But even if the question of safety has been resolved scientists will still face tremendous hurdles, especially in terms of government regulations, before they can start any clinical trials. The US Food and Drug Administration is barred from considering human trials involving edited embryos. In the UK, it is against the law to implant women with genetically modified embryos.

Genetic modification is a highly controversial issue because it affects, not only the child, but also future generations of people. While the demonstration did not create a new baby, once successful there will be no stopping individuals from using the technology to do so. It is a very long road ahead with no clear signs of when scientists will be allowed to move forward.

About Anne Cruz

Anne Cruz is a writer, food enthusiast, and hands-on mom. She has worked as a journalist, digital content editor, and social media consultant. When not pounding the keyboard, she's at the kitchen making home-cooked meals for the family.

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