Genome Editing 101: Applications of Genome Editing
Foreword
For the first time in human history, we not only understand the language of life, but we can also manipulate it. In the past two decades, a lot of advancements have been made to contribute to the realm of genome editing. Genome editing is the combination of techniques that allow us to manipulate the DNA of bacteria, fungi, and even humans. Manipulating genetic codes have an enormous influence and can be used to increase crop yields, produce medicines in bacteria, and even cure genetic diseases.
The Genome Editing 101 series offers to explain the relevant biology of gene editing, the mechanisms by which such techniques work, and the ethical and political problems that arise from this new field of biology. It will be mainly divided into the following chapters:
1. Genome Editing 101: Central Dogma of the Cell
2. Genome Editing 101: Gene Editing Techniques
3. Genome Editing 101: Applications of Genome Editing
4. Genome Editing 101: Politics on Genome Editing
5. Genome Editing 101: Ethical Problems in Genome Editing
6. Genome Editing 101: Future of Genome Editing
Genome Editing 101: Applications of Genome Editing
Although far from being used in the clinic to cure any genetic disease, gene editing tools, most notably CRISPR/Cas9, have been shown to offer significant opportunities in many fields and contexts. The CRISPR-era is still very young, which means that it is developing at an incredibly rapid pace, and new ways of its implementation are found every year. Currently, most efforts are focused on its use in the clinic and agriculture. But, many questions and issues still remain to be answered.
Therapeutic use
The first and major field of application of gene editing techniques has been therapeutics. Many genetic diseases have been identified which are thought to be able to be cured by CRISPR/Cas9. Sickle cell disease, for example, is caused by a single mutation in the beta-globin gene. This gene causes proteins to fold in an erroneous way, which disrupts the stability of red blood cells. Consequently, red blood cells are not able to transport oxygen everywhere it is required (Demirci et al., 2019). Among many symptoms, this may cause chronic tiredness and breathing problems. It has already been shown that CRISPR/Cas9 is able to correct this mutation in cell-lines, though its clinical implementation remains yet to be performed (Demirci et al., 2019).
Besides directly correcting mutations that cause diseases, gene-editing techniques can be used to fight viral reservoirs (Nidhi et al., 2021). When HIV infects the cells that it targets, specific types of immune cells, the virus integrates its DNA into the genome of the cell. Sometimes, this part of the genome is not expressed, which makes the virus latent. At any point in time, this virus may become expressed, which leads to an active infection again (Deeks et al., 2015). Currently, no treatment focuses on this reservoir, because it is simply very difficult to remove it. Because specific sequences of the HIV genome are similar for all the evolving strains, they could theoretically be targeted by CRISPR/Cas9 to be excised and rendered inactive (Nidhi et al., 2021).
The classical example of diseases, cancer, could also be treated with a technique like CRISPR/Cas9. Tumours start to form when specific genes mutate. Two classes of genes are specifically important in oncogenesis, namely proto oncogenes and tumour suppressors (Lee & Muller, 2010). Proto oncogenes are genes that are responsible for the proliferation, or the division, of cells. When they become overexpressed, due to mutations, they are called oncogenes, the expression of which often leads to uncontrolled division of the cell. This uncontrolled division leads to the development of a clump of cells of which the integrity is no longer upheld. This is essentially a tumour. The second class of genes involved are termed tumour suppressors. These typically counteract proto oncogenes and, therefore, keep the cell stable. However, these can mutate too. When certain mutations which decrease the expression of tumour suppressors occur, the cell is much more likely to become a tumour cell as well (Lee & Muller, 2010). These two classes of genes are responsible for the overwhelming amount of cancers that can be found. Because such genes are very well characterised, they could be targeted by CRISPR/Cas9. With this technique, a mutated tumour suppressor could be corrected, and an o