Are we one step closer to the designer baby?
If you haven’t heard of the CRISPR-Cas9 system by now, you have been missing out! This gene-editing system has been creating a buzz in the scientific community since its first appearance in 20141, causing a paradigm shift in how scientists now approach the treatment of diseases.
What is CRISPR-Cas9 you may ask? In a nutshell CRISPR is an abbreviation for ‘clustered regularly interspaced, short palindromic repeats’. Cas9 is an RNA-guided enzyme known as a nuclease, which acts like a pair of molecular ‘scissors’ cutting two strands of DNA at a specific region. DNA repair mechanisms then rebuild the site of breakage using the non-mutant homologous chromosome or a DNA template. This ultimately results in correction of the mutant allele, otherwise known as gene editing.
All eyes have recently been drawn to the work of Shoukrat Mitalipov and his team, who successfully corrected a mutation in the MYBPC3 gene responsible for hypertrophic cardiomyopathy in human embryos. Mutations in this gene have been associated with thickening and stiffening of the left ventricular wall, potentially leading to serious cardiac events including heart failure and sudden cardiac death. By modulating the cell cycle stage at which the DNA was cut and repaired, Mitalipov and his team were able to acquire a high yield of embryos possessing the non-mutant MYBPC3 gene2. Although these findings have important implications in pre-implantation genetic diagnosis and the selection of non-mutant embryos for in vitro fertilization, safe, efficient and accurate genome-wide use of this approach remains to be determined.
Interestingly, it is the non-therapeutic potential of the CRISPR-Cas9 system that has garnered attention of its own. With the advent of gene-editing, the concept of genetically enhanced children termed ‘designer babies’ seems no longer restricted to science fiction. This leads to the question of what gene editing will hold for our future; will we truly be able to select eye colour, increased bone strength, height and manufacture a genetically superior humans? Talks of designer babies have undoubtedly sparked debates on genetic versus therapeutic enhancements. Released in February this year, the US National Academics of Science, Engineering and Medicine concluded that gene editing should be allowed in human embryos, “if the goal was to treat a devastating disease and if there were no other reasonable alternatives”.
So folks, before we get too ahead of ourselves and start envisioning a generation of superior humans, let us regain our senses. Whilst it is clear that the untapped potential of the CRISPR-Cas9 system has yet to be fully unveiled, the birth of the designer baby is premature and unlikely. To all you sci-fi fans out there with your eyes already set on the dawn of the genetically enhanced human, we may just have to stick to our sci-fi movies.
1. Doudna, J.A. & Charpentier, E. (2014) Genome editing: The new frontier of genome engineering with CRISPR-Cas9. Science. 28:346(6213)
2. Ma H. et al. (2017). Correction of a pathogenic mutation in human embryos. Nature. Advance online publication. doi:10.1038/nature23305
3. Ledford, H. (2017). CRISPR fixes disease gene in viable human embryos. Nature News, 548(7665), 13.
4. McGovern Institute for Brain Research MIT. (2014, November 5th) Genome editing with CRISPR-Cas9. [Video file]. Retrieved from https://www.youtube.com/watch?v=2pp17E4E-O8