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Edited-embryo could eliminate inherited disorders

Chinese geneticists have just announced that they have managed to modify the genes of the human embryo. They claim that they can fix the faulty gene that is a major cause blood disorder of β-thalassemia. This success was met with two kinds of attitudes, namely enthusiasm and fear. This project can lead to ethical and moral debate about what should not be done humans. One sign of rejection is when the scientists have submitted a report in the journal Nature, but the report was rejected for publication without apparent reasons.

Whenever humans make a major breakthrough in science, there is a mixed reaction of horror and enthusiasm. When locomotives started to appear, some doctors claimed that if humans travelled at their higher speeds for prolonged periods their heads would explode.

As occurred during the locomotive’s birth, the Chinese experiment has sparked alarm at what many claim is the inevitable slippery slope towards designer babies and a society driven by eugenics, and optimism at the prospect of eradicating devastating inherited disorders.

Unsurprisingly, a higher percentage of people with inherited disorrders see the research favourably than unfavourably, while most of those against tend to be inherited-disorder-free.

Gene editing might eradicate many inherited disorders

Inherited disorders that might eventually be corrected before the baby is born, if scientists pursue human embryo gene editing research, include Cystic fibrosis, Canavan disease, Duchenne muscular dystrophy, Haemophilia, Neurofibromatosis, Polycystic kidney disease, Tay–Sachs disease, Noonan syndrome, and hundreds more. It could change the lives of hundreds of millions of future babies, children and adults.

Junjiu Huang, a gene-function scientist from the University fo Guangzhou in China, and colleagues explained in the journal Protein & Cell how they genetically changed some human embryos in their quest to correct the defective gene that causes β-thalassaemia.

The scientists first submitted their paper to the journal Nature, which refused to publish. They then approached Science, which also turned them down. Both publishers probably walked away for ethical reasons.

Huang and colleagues insisted they are not involved in any form of eugenics. In an effort to calm such fears, they explained that all the embryos they used were non-viable – they were not capable of developing into a fetus. Eugenics is the belief and practice which strives to improve the genetic quality of the human population.

Many want human embryo gene editing banned

Opponents, who fear where these types of experiments could lead to, urge authorities worldwide to ban the practice.

Dr. David King, Director of Human Genetic Alert, said:

“This news emphasises the need for an immediate global ban on the creation of GM designer babies. It is critical that we avoid a eugenic future in which the rich can buy themselves a baby with built-in genetic advantages.”

“It is entirely unnecessary since there are already many ethical ways to avoid thalassaemia. This research is a classic example of scientific careerism – assuring one’s place in the history books even though the research is unnecessary and unethical.”

The Chinese scientists got their embryos from fertility clinics that had created them for IVF (in-vitro fertilization). Each embryo had an extra set of chromosomes because they had been fertilized by two sperm, which made them non-viable. However, they were capable of developing through the first stages.

The procedure affected many non-targeted genes

Huang and team injected CRISPR/Cas9, a complex enzyme, into eighty-six embryos. The enzyme precisely binds and splices DNA at targeted locations. At the same time, they injected a molecule into the embryos that they hoped would correct the faulty gene that causes β-thalassaemia.

They then waited for two days – the time required for the gene-editing to run its course.

Seventy-nine of the eighty-six embryos survived. They genetically tested fifty-four of them and found that 28 embryos had been spliced successfully. However, a disappointingly tiny fraction of them contained the gene-correcting molecule (the new replacement genetic material).

More worryingly, however, they also found that many ‘off-target’ mutations had occurred. In other words, the procedure had made many genes mutate which had not been targeted.

Critics worry that gene editing of human embryos could add undesirable and possibly dreadful genetic traits to the baby, who would not only suffer, but could then pass them off to his or her offspring.

Professor of Cancer Genetics, St. George’s University of London, Shirley Hodgson, said:

“I think that this is a significant departure from currently accepted research practice. Can we be certain that the embryos that the researchers were working on were indeed non-viable?”

“Any proposal to do germline genetic manipulation should be very carefully considered by international regulatory bodies before it should be considered as a serious research prospect.”

We need a set of rules

Dr. Philippa Brice, who works at the British health policy think tank PHG Foundation, said:

“This story underlines the urgent necessity for international dialogue over the ethics of germline gene editing in human embryos, well in advance of any progression towards theoretical clinical application.”

“Recent calls for a moratorium on any such research to allow time for expert and public consideration of what is and is not ethically, socially and indeed legally acceptable with respect to human germline genetic modification should definitely be heeded.”

Ironically, Huang’s team’s failure to carry out a 100% successful experiment is a good thing, Dr. Brice believes. It means that any chance of this technology being used in medical practice is several years away – which gives us time for discussion.

Dr. Brice added:

“Ultimately, the issues boil down to the question of how far we are prepared to go in order to pursue the dream of therapeutic modification of humans.”

Huang’s team not the only one

Four other teams are carrying out similar experiments in China, David Cyranoski and Sara Reardon wrote in the journal Nature. They say they were informed by somebody (unnamed) who claimed to be familiar with developments in the field.

Cyranoski and Reardon quoted Georgo Daley, a stem-cell biologists who works at Harvard Medical School, who said:

“I believe this is the first report of CRISPR/Cas9 applied to human pre-implantation embryos and as such the study is a landmark, as well as a cautionary tale.”

“Their study should be a stern warning to any practitioner who thinks the technology is ready for testing to eradicate disease genes.”

The scientific community is at two minds regarding human embryo gene editing. If it can be shown to be 100% safe, given its potential to eradicate some pretty awful genetic disorders, the majority would probably be in favour.

Making it safe means having a comprehensive set of rules, which currently do not exist, they say.

A number of eminent scientists wrote in Nature in March:

“In our view, genome editing in human embryos using current technologies could have unpredictable effects on future generations. This makes it dangerous and ethically unacceptable.”

“Such research could be exploited for non-therapeutic modifications. We are concerned that a public outcry about such an ethical breach could hinder a promising area of therapeutic development, namely making genetic changes that cannot be inherited.”

About Suzanne McNamara

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