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Can we trust ourselves when it comes to gene editing?

July 15, 2019

Genetic editing could be one of our most powerful tools to treat illness and suffering, but could it change what it means to be human?

One of the most memorable moments of Steven Spielberg’s 1993 dinosaur blockbuster Jurassic Park is the tense dinner table conversation between the assembled scientists on the ethics of the park’s use of genetic engineering. Match point is scored by Jeff Goldblum’s chaos theorist Ian Malcolm:

“Genetic power is the most awesome force the planet has ever seen, but you wield it like a kid that’s found his dad’s gun… your scientists were so preoccupied about whether or not they could, they didn’t stop to think if they should.”

That was 1993. Genetic science has moved on a lot since then. In 1996, Dolly the Sheep became the first fully cloned animal. And in 2003, the human genome was finally fully sequenced.

November 2017 saw the latest milestone in our increasingly intimate and complex relationship with our genes, when 44-year-old Californian Brian Madeux was injected with copies of a corrective gene in an attempt to cure his Hunter’s Disease. The injection was intended to directly edit Madeux’s gene code, removing faulty pieces of the genome and stitch it back together.

If successful, this treatment will be a major step forward for the medical application of gene-editing technology. But are we opening a Pandora’s box? Now that we can, do we need to stop and ask whether or not we should?

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Changing your genes – or those of future generations?

First of all, it’s important to distinguish between two distinct types of genetic editing: somatic and germline.

Every multicellular organism has two types of cell: somatic cells and germ cells. Somatic cells are what make up most of our bodies – our skin, our hair, our blood and organs. Germ cells, on the other hand, are reproductive cells – they can conjoin with another cell at fertilization and create an embryo.

Somatic editing, like that intended to cure Madeux, just edits genes in a given part of the human body, like a form of precision surgery, and it’s an exciting field in biotechnology.

For instance, Casebia, a joint venture between Bayer and CRISPR Therapeutics, aims to apply the techniques of somatic cell editing to relieve some of the most pressing healthcare challenges in the world, including conditions far beyond the reach of traditional medical treatment.

Among these is blindness, of which genetic factors are a leading cause. Blindness comes in many forms, from macular degenerations (the break down of the macula, a small but critical area in the middle of the retina) to retinis pigmentosa (the breakdown and loss of cells in the retina), each of which is the result of hundreds of genetic mutations, that we are now only just beginning to understand.

However, somatic editing lets genetic engineers precisely identify these genes, and take steps to correct them. While the medical application of genome editing will tackle monogenic (single gene) diseases initially, this technique holds the potential to rid humanity of conditions that have blighted us for the whole of our existence as a species.

However, germline editing is a more complicated phenomenon, and much more controversial.

“Some of this amounts to eugenics to me. Parents could feel obliged to eliminate their gene mutations, because of societal reasons, thereby reinforcing stigma and social disparity.”

– Professor Ernst-Ludwig Winnacker, former Secretary General of the Human Frontier Science Program Organization

The problem with germline

Germline editing means tampering with genes that carry the genetic information that would be replicated throughout all cells that are reproduced following the genetic modification. This means that these edits could be passed on to the patient’s future children. And grandchildren. And eventually, potentially, the whole of humanity.

Unsurprisingly, this potential for germline editing to impact future generations, not just the current subject, poses substantially greater ethical issues. These can be broken down into three key areas:

1) Consent

As future generations have no say in how we edit their inheritable genes, can we say it’s ethical to make such momentous changes in what it means to be human without the consent of the subject? Particularly as those genes will not just be inherited by our children, but by our children’s children, and our children’s children’s children, ad infinitum.

It means that a medical choice made today could impact the lives of people not even born yet – and in ways in which we cannot be certain.

2) Complexity

While we have made significant process in understanding human genetics, gene editing is currently not a totally precise science. Genomes are complex systems – every gene within a genome is interrelated, and we don’t really know how changing one gene may affect others.

The real challenge comes from the fact that some genetic attributes are known as multigenic expressions, meaning they require the cooperation of many different genes. This not only makes performing precise genetic editing difficult – it could also risk giving rise to negative, unanticipated features.

“Things like autism, or schizophrenia, have hereditary components, but there are hundreds of genes involved,” says Professor Ernst-Ludwig Winnacker, previously the Secretary General of the Human Frontier Science Program Organization and a former member of the German National Ethics Board. “This interconnection is not understood at all. Nobody can fully predict what will happen if you make changes in the genome. It makes experimenting on the germline dangerous.”

While the complexity issue exists in somatic gene editing, in these cases the editing can proceed in steps, allowing doctors to make allowances for unexpected gene expressions and correct them. These options do not exist in germline editing. “There could be unintended consequences,” says Professor Winnacker. But once you edit the germline, there’s no going back for the inheritors of those genes. “There's no step in the reproductive field. The only step is a baby.”

3) Social Risks

Being able to accurately edit embryonic germline cells could also present new problems, particularly in how we conceive of human beings, individually and socially. “A real concern is that you create a two-class society, split between those who can afford germline editing, if it ever works, and those who cannot afford it,” says Professor Winnacker.

This may start with an attempt to eradicate harmful conditions, but the boundary for what is acceptable to edit could get pushed further to include height, weight or eye color. “Some of this amounts to eugenics to me,” says Professor Winnacker, referencing the extremely controversial movement of the late 19th and early 20th centuries that fed into the rise of fascism. If this were allowed, warns Winnacker, “parents could feel obliged to eliminate their gene mutations, because of societal reasons, thereby reinforcing stigma and social disparity.”

Either way, in the wrong hands, gene editing technology could end up transforming how we think of each other as humans.

Protecting the future of humanity

These ethical debates used to be consigned to speculative fiction. But as genetic editing moves from sci fi into real-world laboratories, the need to define the moral limits of science grows. 

In December 2015, the International Summit on Human Gene Editing (organized by the national science academies of the United States, the United Kingdom, and China), on whose board Professor Winnacker sat, concluded that a moratorium on “genetic alterations in gametes or embryos, which will be carried by all of the cells of a resulting child and will be passed onto subsequent generations as part of the human gene pool,” would be necessary for the technology to develop in a responsible manner.

The degree to which these recommendations have been taken up internationally varies, and around the world laws and guidelines vary widely about what germline, or hereditary, research is allowed. Today, 40 countries have passed laws restricting or banning germline modification. Some ban any research; some allow only lab research but not pregnancies; some have no policies at all.

Gene editing technology has enormous potential – and enormous power. In order for us to realize the immense benefits that gene editing promises, we need to move forward on an ethical, scientific consensus. Sometimes there is simply too much we don’t know about such complex systems as human genetics and reproduction. Before pressing ahead with research just because we can, it’s important to ask whether or not we should.

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