Gene editing: a molecular miracle
Humans grow and develop based on the instructions contained in our genetic material. A normal human cell should contain exactly 46 chromosomes. Chromosomes contain smaller units of genetic material called DNA inside the nucleus. DNA is a sequence of letters (A, T, C and G) that spell out the genetic code. The DNA is organised like words and sentences called genes.
Humans have approximately 25,000 functional genes and each one influences a part of development and unique functions. These genes usually come in pairs. One copy is inherited from our mother and another from our father. A change in the spelling of a DNA sequence or the gene is called a mutation. Every person’s DNA contains mutations which are usually harmless. However, some mutations are responsible for causing specific disease.
A genetic disorder is a genetic problem caused by one or more abnormalities in the genome. Most genetic disorders are quite rare and affect one person in every several thousands or millions. Genetic disorders may be hereditary, passed down from the parents' genes. In other genetic disorders, defects may be caused by new mutations or changes to the DNA. In such cases, the defect will only be passed down if it occurs in the germ line.
What is gene editing?
Genome editing, or genome engineering is a type of genetic engineering in which DNA is inserted, deleted, modified or replaced in the genome of a living organism for the betterment of human health. The characteristics of all living organisms are determined by their genetic material, or DNA. Genes are segments of DNA which provide the code for particular functions or characteristics.
Normally, when one strand of DNA is cut or damaged, it is repaired by enzymes which use the information in the other strand as a template. Gene editing uses this process but provides new repair information to change the DNA strand. By editing genes, it is possible to make changes to organisms, such as changing the version of a gene from one that causes disease to one that does not.
A technique called Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) has enabled scientists increasing the speed, ease and accuracy of gene editing in a greater extent. It has created a buzz in the global healthcare industry. The invention of CRISPR-Cas9 gene editing tools is one of the greatest scientific revolutions of this generation. Accordingly, this system has the potential to be employed to change each gene from all 23 pairs of human chromosomes with unprecedented accuracy, without inducing undesired mutations.
How is gene editing being used in healthcare?
Among the approximately 25,000 identified genes in the human genome, there are mutations in over 3,000 that have been linked to disease. Gene editing tools can now potentially be used to replace faulty or disease causing genes. Gene editing in the early stage embryo potentially allows those modifications to be passed on to future generations. Researchers have used CRISPR in human embryos to repair a gene defect that would cause a potentially deadly heart defect; modify genes responsible for ß-thalassemia, a potentially fatal blood disorder; and to modify genes in immune cells to develop increased HIV resistance.
Gene editing technology plays a great role other than non-human health applications too such as agriculture and plant genomics in enhancing nutrient efficiency, improving drought resistance and extending shelf life of food crops etc. In a sense the technology has emerged with the great blessing for the human health and wellness.
It is obvious that the technology may have downside too. Working on embryo may affect future generations, their characteristics, and behaviour patterns without their consent. Thus it must be pin pointed in the guideline containing ethical issue as the priority.
The writer is the CEO of NIPRO JMI Pharma Ltd. Email: firstname.lastname@example.org