Jyoti Vakhlu
Recently, the National Academy of Sciences USA released a 261 page report on the title “human genome editing: science, ethics and governance”.
Genome editing is a kind of biological engineering in which DNA is inserted, deleted or replaced in a genome of living organism (usually embryo) using molecular scissors” called CRISPR. For basic understanding genome editing can be compared to editing any script by insert-ing, deleting or replacing a word or an alphabet. In genome gene/nucleotides are edited and in script words/alphabets are edited.
In human genome the information is packed in 23 pairs of chromosome, one set of pair contributed by each parent. This information is written with only 4 alphabets A, T, G, C but carries coded information for all the processes that we require throughout the life. This coded information is also subjected to various pres-sures/factors that can change this information into wrong message which, at times, can result in genetic disorders. Therefore, the wrong/altered information carried by one of the parents may be passed on to the offspring causing a particular genetic disorder. If by chance genetic disorder is not developed in the offspring, it nevertheless can act as a potential carrier of that disease. As one cannot choose one’s parents and thus, has no control over the type of life information one may receive. It is established now that the basis of all hereditary information (disorder) are genes residing in chromosomes. The only choice for informed parents with family history of genetic disorders is to screen the amniotic fluid for defective genes. If genetic disorder is found to be life threatening, the genetic counselor suggests for medical termination of pregnancy.
However in human reproductive biology, the revolution came with advantage of in vitro fertilization, gene therapy and triparental embryo technology to name a few. Triparental embryo technology takes care of the genetic disorder wherein the source of genetic defect is mitochondria. In addition to nuclei of both parents, mother’s mitochondria also contribute the genetic material hence can be store house of some defects. In this technology, nuclei of male and female parents are fused and transferred to an enucleated egg of third parent (Two mothers and a father). Since the mitochondria is supplied by the egg of the mother as sperm is devoid of any cytoplasm, this defect is taken care of. However this technology still cannot solve the issue of the genetic disorders that are created/transferred by the defect in genes residing in the nuclei. Reproductive biologists have been trying for decades to develop a technology that can edit the faulty gene in the babies inherited from the parents. However the application of CRISPR cas technology ( just few year old discovery) to human embryos, sperm, or eggs can precisely edit the defective gene and replace it with healthy gene if need be. Scientists are now racing to apply CRISPR as an even more effective way to perform gene therapy on adults, including to treat cancer and muscular dystrophy.
Genome editing technology modifies the embryos and this technique is in sharp distinction to gene therapy where DNA of adults and children is modified to correct any genetic disorder. Gene therapy, is a well-established part of medical research, has no scope for actually designing babies and hence does not raise the same ethical questions. However, there are ethical, legal and moral issues associated with genome editing technology. In addition to the severe genetic disorders this technology can also be used to design babies with specific physical features or intelligence, provided the genes for such trait are known. But there is no denying that genome editing is a boon to the couples who suffer from genetic disorders such as beta thalassemia or cystic fibrosis, as this technology provides only option to them to have healthy children free from the inherited disorder.
Researchers also argue that the line between serious disease and enhancement is actually hard to define. For example editing genome for prevention of various contagious disease is also genome enhancement by design and similarly selection of one type of physical feature over other may be advantageous in particular environment. Another worry is that controlling the technology like nuclear technology may prove difficult as there are no uniform laws in all the countries and some countries may not even know of existence of such technology leave alone having law controlling it. Researchers and doctors can identify the country and edit the genome of embryos as per the choice of the parents in case the country of origin does not allow editing human embryos.
Though there are ethical, moral and legal issues involved in genome editing to create perfect babies but for the moment go ahead has been given to this technology and time will be the best judge.
(The author is a Professor & Director School of Biotechnology University of Jammu, Jammu.)
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