On September 9th PBS series NOVA presented a two hour program devoted to the genetic technique CRISPR (clustered regularly interspaced short palindromic repeats). It’s a technique that allows for gene editing. You can read about by clicking the link above. The PBS program does a pretty good job of explaining how the technique works and how it might eventually be used.
It goes completely overboard when it starts discussing the possibility of ‘designer babies’ – ie, children produced by germ cells reprogrammed to induce desirable traits and characteristics. Despite having access to some of the world’s leading geneticists the show failed to discuss what genes control and what they don’t.
The genetic process is far more complicated than presented on the program. In order to act, a gene must be transcribed – it forms a single strand RNA molecule messenger RNA (transcription). The mRNA acts as an intermediate between the DNA gene and its final protein product. Translation is the process by which a mature mRNA molecule is used as a template for synthesizing a new protein. Post-translational events may be of immense importance to the organism that contains the gene and may be random.
Consider the first cloned cat, ‘CC’ for carbon copy. Her genetic donor ‘Rainbow’ was a calico domestic shorthair. CC was brown tabby and white domestic shorthair. Not only did the two cats look entirely different, they had different personalities. One was shy while the other was friendly and outgoing. The color difference was due to X-inactivation and epigenetic re-programming, which normally occurs in a fertilized embryo before implantation. The personality difference is not yet explainable. The point is that genes can only take you so far. Post-translational changes are often random and can produce effects that go beyond the genetic code. Thus, two genetically identical animals were very different. Also, the biological processes initiated by a gene may have outcomes influenced by events after the encoding of a protein and thus may be disconnected from the gene.
Gene editing can potentially be useful in correcting disorders that are due to a mutation in a single gene such as Huntington’s Disease, Sickle Cell Anemia, and Hemophilia A. While the technique is not yet ready to correct these genetic disorders, it’s likely that it will be effective relatively soon. I’m assuming that it will be free of unwanted effects.
Diseases that have multiple causations are much less likely to be remedied by CRISPR or any other gene editing process. This resistance to gene manipulation is because most important human diseases are a complex mix of genetic, post-translational, and environmental factors and will require a fix more involved than the insertion or deletion of a gene.
When it comes to ‘designer babies’, whatever they may be, even a perfect knowledge and editing of the human genome is unlikely to produce smarter, faster, better looking people, or whatever human characteristic is thought desirable by anxious would be parents. Human behavior is likely a far more complex phenomenon than the Florida hurricane that had as its initial cause the flapping of a butterfly’s wings in west Africa.
You can fiddle with the human genome till the heat death of the universe and you’ll not make another Franz Schubert. In fact, you could clone him and you’d still not get another Schubert. The factors that produced him are unknowable and gone.
The PBS show contained not a hint of the complexity of making a human, much of which is remote from the genome. It spent a lot of time discussing the ethics of something that was beyond CRISPR gene editing. Still it was informative and worth watching if you are aware of the undiscussed limitations of genetic rearranging. I’m not arguing that CRISPR and its like may not be useful. They hold tremendous promise to alleviate much human suffering and to make better plants and animals. But making us smarter, better behaved, and more creative is science fiction.
