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Does gene editing hold key to better healthcare?


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Doctors believe this will revolutionalise medicine, but there are ethical and safety concerns

Last month scientists in the US used a gene editing tool inside a human body to try to correct a gene carrying an inherited form of blindness, for the first time ever.

Conducted at the Oregon Health and Science University on March 4, the process involved injecting the microscopic tool into the eye of a volunteer, hoping to make him see.  It will take them a few weeks to find out whether it worked.

Medical circles are already excited, with doctors around the world terming it a “new era in medicine”, saying it makes editing the human DNA much more effective.

Should it be successful and safe, it will be tried on 18 patients.

However, after this incident, people got more concerned about the safety of this technology.

So, what is gene editing?

This medical innovation, also called genome editing or gene engineering, involves the use of biotechnological methods to alter the genetic makeup of animals or plants with the core aim of improving them. This can be done by replacing, deleting or adding a DNA sequence to correct a genetic disorder or normalise internal or external body functions.

Simply put, it is like using a pair of scissors to cut off unwanted base pairs of a DNA sequence.

Which tools or methods are used for the procedure?

Four methods exist. The earliest method involved the use of restriction enzymes in the 70s.

Zinc Finger Nucleases (ZFNs) is the method developed in 80s as medical researchers kept looking for a better, precise way of gene editing.

A third method emerged in 2011, which was an improvement of ZFNs known as Transcription Activator-Like Effector Nucleases.

However, in 2012, scientists discovered the fastest and easiest method of genome editing derived from CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats) -Cas9, a system that has long existed in bacteria to help them fight off invading viruses.

What diseases can be controlled using CRISPR-Cas9?

It is being explored in research on a wide variety of diseases, including cystic fibrosis, haemophilia and sickle cell disease. It also holds promise for the treatment and prevention of cancer, heart disease, mental illness and HIV infection.

Tackling obesity and creating hornless cows are other uses.

Optimistically, CRISPR might help us develop drought-tolerant crops and create powerful new antibiotics. It could one day even allow us to wipe out entire populations of malaria-spreading mosquitoes.

How much does it cost?

It can take months to design a single, customised protein at a cost of more than Sh100,000 when using older gene editing tools.

With CRISPR, scientists can create a short RNA template in just a few days using free software and a DNA starter kit that costs Sh6,500 plus shipping.

What are the health risks?

Ethical concerns arise when genome editing, using CRISPR-Cas9, is used to alter human genomes.

Most of the changes introduced with gene editing are limited to somatic cells, which are cells other than egg and sperm cells.

These changes affect only certain tissues and are not passed from one generation to the next.

However, changes made to genes in egg or sperm cells (germline cells) or in the genes of an embryo could be passed to future generations.

Germline cell and embryo gene editing bring up a number of ethical challenges, including whether it would be permissible to use this technology to enhance normal human traits (such as height, skin colour, hair type or intelligence).

That follows recent studies showing that CRISPR-edited cells can inadvertently trigger cancer. That is why many scientists argue that experiments in humans are premature.

The body’s own immune system could thwart some efforts to develop gene therapies based on CRISPR-Cas9, according to a 2018 study. Based on these concerns, germline cell and embryo gene editing are illegal in many countries.

Any legal ramifications so far?

On December 30, 2019, a court in China sentenced He Jiankui, a researcher, to three years in prison for carrying out illegal medical practices. He had shocked the global medical community when he claimed to have created the world’s first genetically edited babies – twin girls. The court found him guilty of forging approval documents from ethics review boards to recruit couples in which the man had HIV and the woman did not.

Way forward?

World governments must show commitment to controlling how CRISPR is used. Although it has the potential to redefine the future of medicine, a self regulation framework may not work, nor a moratorium: a self-imposed ban of a few years before anyone tries using the technology on the human germline again since the twin girl story.

Africa, which has not done any substantial research work in this field, needs to develop the right policies regarding the use of the technology in breeding and agriculture, to edit out crop diseases before considering trying the same on humans. Kenya is warming up to the technology, in a bid to catch up with the rest of the world, as Pwani University students are conducting research on enhanced shelf life for cassava using gene editing.

While the risks for gene editing in humans currently outweigh the benefits experts agree that should not discourage more research into this field, since science has always proven a sustainable remedy to many diseases the human body is exposed to.