Imagine a world where you are asked such questions when you plan to have a baby. Would you like blue eyes? Dark hair? High IQ? A future Michael Jordan or Pablo Picasso? Sounds like a version of the Brave New World? It isn’t. Scientists are technologically on their way to play with the human genome as they like. They call this “genome editing” and it may not be as disturbing as it sounds. Well, if we are careful about how to use it…
10 years ago, scientists discovered that bacteria protect themselves from viruses by finding and chopping specific regions of the viral genome, thereby destroying them. This clever machinery with its ‘navigation’ and ‘scissors’ devices was part of the bacterial immune system, yet it could be adapted and used in other organisms, such as human cells.
Using this system, scientists can cut the human genome in any region they want. Once the target region is cut, the natural repair mechanisms of the cell are utilized to make the desired changes, such as deletion or addition of sequences to a target gene as well as turning its activity on or off. This so-called “CRISPR” system is not the only system for genome editing, but in comparison to others, it has lower costs, faster application times and, most importantly, higher precision at targeting regions.
So CRISPR is like the One Ring, but how can we benefit from it? And what does it have to do with our future babies?
Scientists cannot experiment on humans, so they use model organisms, such as roundworm, fruit fly, zebrafish and mouse, depending on their research purposes. To investigate the function of a gene, scientists have to inactivate this gene in a model organism and look for outcomes. To understand what goes wrong in a genetic disease and to find ways of treatment, scientists need to mimic the underlying genetic mutations found in patients using model organisms. Genome editing techniques, particularly CRISPR, revolutionized the generation of such model organisms. Before CRISPR, only one mutation could be mimicked, now multiple mutations can be mimicked with high efficiency.
Here are some examples of CRISPR-magic. Scientists could mimic specific rearrangements in the genome that cause lung cancer in adult mice; something that was not feasible before CRISPR. Elsewhere, in an attempt to generate a suitable non-human organ donor, scientists modified more than 60 genes, which would cause infection in human transplant recipients, in the pig genome. In another study, a mutation that causes cystic fibrosis was corrected in intestinal stem cells from patients that were grown in laboratory conditions.
All of this sounds fascinating and very promising for the treatment of human diseases, but there is a catch: what if someone starts genome editing in human germ cells (eggs and sperms) or embryos that would have heritable effects?
On one hand, genome editing of human embryos could potentially be a remedy for people with a family history of genetic diseases that cannot be treated in another way. Mutations that cause the corresponding genetic disease would be removed from the potential baby and this would be heritable, meaning future generations would not have these mutations anymore. On the other hand, the technology is so new that we do not know what the long-term effects to human health would be or whether if it is safe to be inherited through generations. And the crazy idea of tackling with embryos to design the ‘perfect baby’ is certainly not a pleasant one.
Well, using genome editing to treat patients is still a long way off because the technology is still developing, and the good news is that scientists and other interested parties are aware of the ethical issues surrounding the technology.
In her commentary in the Nature journal, Jennifer Doudna, one of the pioneers of CRISPR technology, says “I am excited about the potential for genome engineering to have a positive impact on human life, and on our basic understanding of biological systems….But I also think that today’s scientists could be better prepared to think about and shape the societal, ethical and ecological consequences of their work.”
So we shall wait and see how this groundbreaking technology will impact our and the future generations’ lives, but also, take part in debates about its potential outcomes where possible.
If you would like to read more;
Centers for Disease Control and Prevention (CDC) has compiled a nice list of articles and posts about ethical aspects of gene therapy and genome editing, as well as recent insights.
Nature journal has prepared a short list of facts on genome editing.
Featured image from http://www.pixabay.com.
Doudna, J. (22 December 2015). Genome-editing revolution: My whirlwind year with CRISPR. Nature Comment [online] http://www.nature.com/news/genome-editing-revolution-my-whirlwind-year-with-crispr-1.19063#/b5
Schwank, G. et al. (2013). Functional repair of CFTR by CRISPR/Cas9 in intestinal stem cell organoids of cystic fibrosis patients. Cell stem cell, 13, 653-658. Pubmed: 24315439
Yang, L. et al. (2015). Genome-wide inactivation of porcine endogenous retroviruses (PERVs). Science, 350, 1101-1104. Pubmed: 26456528