What is that? Dr. Ruchika Irene Dillu explains

What is the genome?

The genome is defined as a complete set of genetic instructions which are encoded in a double helix structure formed by base pairs attached to a sugar-phosphate backbone commonly called deoxyribonucleic acid (DNA). Each genome contains all the information needed to build an organism and allow it to grow and develop.

Evolution of genetic mapping

The concept of genetic mapping has evolved gradually. Many early discoveries such as the fundamental law of heredity by Gregor Mendel in the early 19th century, DNA structure by James Watson and Francis Crick in 1953, genetic trisomy syndrome, Turner and Klinefelter syndromes first published in 1959, etc. important milestones for advancing the study of genomes as it is applied today.

The milestone achievement of exploration in history is the Human Genome Project (HGP) which was started in 1990 and declared essentially complete in 2003 with 80% of the genome. Full genome identification was done in 2021 and final uninterrupted assembly was completed in January 2022. The main objective of the HGP was to map all genes of human beings and understand their function. The development of newer, better and cheaper tools and techniques to achieve the goal of the HGP was the natural outcome of the development process.

What is genetic mapping?

At the simplest level, genetic mapping is a method of determining the location of genes on the chromosome. Gene mapping – linkage mapping – provides clues to the chromosome containing the gene and the precise location of the gene on that chromosome. Various laboratory techniques use blood, saliva, or individual tissue samples to isolate DNA from these samples and examine it for patterns that are unique to an individual.

Genetic mapping in India

Inspired by the human genome project, the biotechnology department approved a genetic mapping project – Genome India Project (GIP) in 2020. The project aims to construct an “Indian reference genome”, based on which the traits of the Diverse Indian population could be understood. The project has been described by the researchers as the “first scratching of the surface of India’s vast genetic diversity”.

The Genome India project is a collaborative research project of more than 20 universities across the country and is led by the Center for Brain Research, Indian Institute of Science, Bangalore. The results of this project will collectively facilitate future comprehensive human genetic studies for researchers across India. Such studies are expected to be transformational for the country’s long-term health care scenario.

Application of genetic mapping in health care

Until now, most medical treatments have been designed for the “average patient”. With this “one size fits all” approach, treatments can be very effective for some patients, but not for others. With the advent of modern genomics, phenotypic differences can be mapped to genotypic differences via precision medicine.

Precision medicine approaches to cancer have become prime examples of the opportunities offered by this strategy, for example in the pre-genomic era chemotherapy was widely used with varying success. With the evolution of cancer genome sequencing, targeted therapies have led to a dramatic change in treatment response, drug tolerance and improved survival. 19 of the 49 new therapeutic molecular entities approved by the US FDA in 2020 – as well as one new cell therapy – are personalized drugs.

Precision genomics has led to the new classification of biologically diverse diseases such as dementia. Genetic maps have been used successfully to find the gene responsible for relatively rare diseases such as cystic fibrosis and Duchenne muscular dystrophy. He has also made significant contributions to the identification of many genes believed to play a role in disease biology and the treatment of more common disorders such as asthma, heart disease, diabetes, cancer and psychiatric disorders.

Moreover, genetic mapping plays an essential role in modern diagnostic procedures. A well-known example is that of antenatal care, which establishes evidence of the association of diseases transmitted from parent to child.

Risk of genetic mapping

The risks of genetic mapping are not limited to:

Genetic discrimination: Discrimination based on genetic makeup in case of health insurance, employment, etc. is possible. This could fuel burning questions about the indigenous population, race/caste-based politics and tracing of origins.

Genome editing: Gene therapy has the potential to treat several diseases, there are ethical concerns about the extent to which it can be used – a double-edged sword that could lead to genetic enhancement.

Privacy: There are privacy concerns regarding research participants’ consent, use of results, and associated risks. There are cultural and knowledge barriers to fully understanding the potential benefits and identifying the risks associated with genetic mapping. In addition, the issue of data storage and protection must be addressed in view of the possibility of data misuse.

Unequal access: Limited access to genetic testing and preventative drugs could deepen current inequality and create social tensions.

takeaway message

Gene mapping has the potential to transform healthcare through precision medicine: raising awareness of wellness, treating rare genetic diseases, hard-to-treat cancers and debilitating chronic diseases. However, the various risks and issues associated with genetic mapping, storage and use of genetic data should be considered and a clear policy developed for better access, accessibility and use of this new technology.

(Dr. Ruchika Irene Dillu, MD, Pharmacology)

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