The era of genome editing

By Olivia Howcroft

During the first three days of December 2015, in Washington D.C, the International Summit on Human Gene Editing was held. Various aspects of gene therapy were covered, including the societal implication of the emerging technology, the limits to our understanding of it and the governance at an institutional, national and international level. These have all been concerns of both professionals and the public. Despite the benefits of gene therapy, it is not surprising that some are hesitant to agree with this new development; since the 1950s there have been a number of scientific errors and catastrophes such as Chernobyl, Organophosphate pesticides, Thalidomide, and more recently the BSE (Mad Cows disease). The mistrust that a great deal of the public have towards gene therapy may stem from the widespread worry that these technologies will disrupt world order, and belief that interfering with nature can be problematic.  Although many doubts may be unwarranted, there are suspected risks that do need precautions, for example controlling aggressive situations such as the war on terror. As gene therapy allows for quick and easy changes in genetic material, it follows that, in the hands of groups bent on biological warfare, this could be harmful to both humanity and the environment. Examples of recent use of biological warfare are the 2001 anthrax attack in the USA with contaminated letters and the 1984 Salmonella outbreak in salad bars in Oregon which was caused by members of a religious commune. A total of 10 restaurants were affected, with a 751 people contracting Salmonella gastroenteritis, associated with eating or working at these restaurants.

The current tool for editing genes was developed by researchers at the University of California, Berkeley; Harvard and MIT, and is called CRISPR. The technology allows for quick and easy modifications of the genome: in early 2013 it was proven that this could be used to genetically engineer any type of animal cells, including human ones. One application, for example, is to prevent the spread of malaria by editing a gene that is essential for female fertility in mosquitoes. This usually has two outcomes: either the female fails to lay eggs or the laid eggs do not hatch. However, when dealing with wild animals that breed within wild populations, there must be regulations to prevent the modification from spreading to every new generation and running out of control. A possible implication of this is the reduction in genetic variation of the species as the genetic modification spreads through the population. The risk of a new scientific development leading to something that we cannot control is at the heart of the public’s doubt over gene therapy and other such advancements; it is what has called for strict and validated biosafety measures with public review and consent.

CRISPR is now being used in primates

Genome editing provides an opportunity to create mutations linked to human diseases, where brain disorders such as autism, schizophrenia, Alzheimer’s disease, and bipolar disorder are of particular interest. The neural circuits are very different in animals other than primates and humans, and the affected behaviours vary substantially. Scientists now hope to discover more about human disorders of the brain by editing primate genes. “The idea that we can modify primates easily with this technology is powerful,” says Jennifer Doudna, a professor of molecular and cell biology at the University of California, Berkeley, and a developer of CRISPR. CRISPR will allow researchers to identify which mutations or which combinations of mutations cause certain diseases. Researchers also hope that by mutating the gene SHANK3 in fertilized eggs, which is correlated with a high probability of autism, they will be able to identify drugs that alleviate autism.

Use of human embryos and non-therapeutic uses

After the use of CRISPR in primates, controversy has been sparked with reports of fertility doctors editing genes of human embryos. It is alarming for some that we have the ability to do this, however the safety concerns have been highlighted, with the implications that even small errors would amount to serious consequences. There’s also the ethical issue of the genetic alterations being passed onto subsequent generations. There is certainly a level of social mistrust derived from the question of whether CRISPR will be used discriminately, and people worry about how fluid the definitions of ‘therapy’ and ‘enhancement’ are. However the process is far too complex and poorly understood to target the modification of many traits in a genome. Hence the fear over development of ‘designer babies’ with modifications, for instance, to intelligence, has been  described by experts such as Hank Greely, director of the Centre for Law and the Biosciences at Stanford as “borderline crazy, borderline implausible.”

Illustration: Caroline Davis2010 via Flickr

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