We are living in an era where we are not just striving to make human lives comfortable but also to reach immortality. Though immortality is yet far from realization, we have managed so far to outlive our ancestors. Due to advancements in the field of biology and biotechnology, we are now able to eradicate epidemics well before they could claim millions of lives, as was the case in past. For instance, the Black Death or the Great Plague, as it was known, claimed around 75 to 200 million lives in Eurasia from 1347 to 1351[1], while the recent Ebola Virus epidemic, which inflicted the West-African population, claimed only 11,310 lives from 2013 to 2016[2]. However, the scientific pursuit does not end at overcoming epidemics. With improved understanding of the human genome, we are currently trying to cure diseases that are rooted in our genes. By the use of genetic engineering, we could alter the genes that cause deadly diseases. Genetic engineering is, thus, the future we all are looking forward to.
we are now able to eradicate epidemics well before they could claim millions of lives
Genetic engineering is defined as the modification or editing of the genetic makeup of an organism. It involves removing, adding or replacing particular genes from DNA that govern all the functions and traits of an organism.[3] Genetic engineering tools have already been used in manipulating plants’ and animals’ genes for the enhanced quality yield of products for quite a long time. Lately, there has been more effort put in understanding the human genome i.e. understanding the functions of various genes in human DNA. This will ultimately help us to understand genetic diseases and the specific mutant genes causing them. Genetic engineering tools could then enable us to modify the mutant genes for the termination of the diseases.
Several gene-editing methods are commercially in use to modify genes of plants and microorganisms (mainly bacteria and viruses) for high quality yield of commercial products. They include plasmid method, vector method using virus as a vector and biolistic method or gene gun method.[4] However, recently a new gene-editing tool has been invented which is more precise in targeting genetic modification. It is called CRISPR-Cas9, standing for Clustered Regularly Interspaced Short Palindromic Repeats. CRISPR basically comprises of an enzyme called Cas9 and a guide RNA. The guide RNA helps in finding the location of a mutant gene and the enzyme helps in cutting the strand of DNA at that location. The DNA break is then joined naturally by a process called non-homologous end-joining (NHEJ). This process is unsuitable because it causes additional mutations due to the insertion and deletion of some DNA part at the joining point. However, in some cases, targeted cells activate a substitute DNA repair method called homology-directed repair (HDR), which uses the non-mutant DNA strands of the healthy partner as a template for the correction of mutant gene.[5]
CRISPR technology is currently used for introducing mutations in the genes of animals for testing purpose i.e. for observing the effects of the presence and absence of specific genes in animals. This helps in knowing the specific functions of similar genes in human body, hence, letting us know which genes could cause particular genetic disorders. In those knock-out gene experiments with the animals, NHEJ is usually used for the repair of DNA breaks, leading to the addition of the mutants.[6] Therefore, the application of gene-editing for gene-therapy is still restricted in humans.
However, research activities have been carried out using the CRISPR-Cas9 technology in human embryos. A team led by Oregon Health and Science University, USA, involving experts from a number of prestigious institutes across the world, demonstrated an effective way to edit genes using CRISPR in the human embryos before implantation. They performed experiments on removing a mutant gene that causes hypertrophic cardiomyopathy (HCM) – a condition in which heart does not pump blood efficiently due to the thickening of some parts of heart walls. This condition at times leads to heart failure and hence, sudden death of otherwise a perfectly normal and healthy person. Currently, it occurs approximately in 1 in every 500 adults and is only treated symptomatically. The experimental results of the study were mostly positive except for the likely introduction of new mutants due to NHEJ use for DNA repair.[7]
Gene-editing in human embryos is prohibited in many developed countries
The research, thus, promises a potential to prevent such genetic disorders by removing the mutant genes from the lineage altogether. However, the risks involved are still great, since multiple genes might control a single trait or a single gene might control multiple traits and hence, removing the mutant gene could cause unforeseen effects that might be deadlier than the earlier disease that is being cured. Therefore, gene-editing in human embryos is prohibited in many developed countries including USA, Canada and UK for safety concerns. China, however, has no such restrictions in place and one of the Chinese scientists recently carried out an experiment on human genome. He inserted HIV-resistant genes in human embryos and twins have been born with their genes modified. The twins are under administration for the check of any side effects. There has been much criticism from scientific community on that reckless experiment, for there are already many effective ways to prevent HIV in healthy individuals such as safe sex. The experiment, hence, exposes healthy normal children to risks of gene editing for no real benefit.[8]
Designer babies is the term used for babies made after genetic modification
Gene-editing is still experimental and is associated with off-target mutations, capable of causing genetic problems early or later in life, including the development of cancer. Thus, its use in humans is prohibited yet. However, given the present rate of scientific development, the human genome editing would likely be safer to use in future and then it would not only be used for gene therapy but for other traits specification too for enhancement purpose. Designer babies is the term used for babies made after genetic modification. With increased advancement in genetic engineering technology, parents would design their babies by choosing genes that provide the best traits i.e. higher intelligence or greater beauty. This would probably cause imbalance in human society. Due to the cost of the process, only the rich will be able to afford it, thus widening the gap between the poor and the rich not only in terms of money but intelligence and beauty too. This will generate many ethical and religious issues, since it involves playing with the natural process of babies’ birth. Hence, even if the technology becomes safe, it would take a long time before it can be used freely.
[1] “Black Death – Wikipedia.” https://en.wikipedia.org/wiki/Black_Death. Accessed 1 Jan. 2019.
[2] “West African Ebola virus epidemic – Wikipedia.” Accessed January 1, 2019. https://en.wikipedia.org/wiki/West_African_Ebola_virus_epidemic.
[3] “Genetic engineering – Wikipedia.” Accessed January 1, 2019. https://en.wikipedia.org/wiki/Genetic_engineering.
[4] “Methods of Genetic Engineering – mrlloyder.” Accessed January 1, 2019. https://mrlloyder.weebly.com/methods-of-genetic-engineering.html.
[5] “Correction of a pathogenic gene mutation in human embryos | Nature.” Accessed January 1, 2019. https://www.nature.com/articles/nature23305.
[6] “Correction of a pathogenic gene mutation in human embryos | Nature.” Accessed January 1, 2019. https://www.nature.com/articles/nature23305.
[7] “Correction of a pathogenic gene mutation in human embryos | Nature.” Accessed January 1, 2019. https://www.nature.com/articles/nature23305.
[8] “World’s first gene-edited babies created in China, claims scientist ….” Accessed January 1, 2019. https://www.theguardian.com/science/2018/nov/26/worlds-first-gene-edited-babies-created-in-china-claims-scientist.
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