By Dr. Kinjal Desai
“This book is the story of the birth, growth, and future of one of the most powerful and dangerous ideas in the history of science: the “gene,” the fundamental unit of heredity, and the basic unit of all biological information.” – Siddhartha Mukherjee, in ‘The Gene.’
Siddhartha Mukherjee’s ‘The Gene: An Intimate History’ is a deeply engaging and fascinating history of human genetics. Interweaving the text with anecdotes of his own genetic history, the oncologist and author walks his readers through the series of scientific discoveries and coincidences that has brought us closer to understanding the elusive unit of inheritance, the gene, along with its properties and capabilities. Throughout the book, he also merges the scientific timeline with a historical and social perspective, shedding light on the misuse of genetics, and exploring what the future of genetic understanding and technology holds.
In his first book, ‘The Emperor of all Maladies’, Mukherjee told the story of the biography of cancer, and here, he follows up by addressing the notion that if cancer is caused by genetic abnormalities, then what is genetic normalcy?
Starting with the riveting story of Mendel’s discovery using pea plants, that physical traits can be passed on from one generation to another, he leads us into Charles Darwin’s arrival at the theory of natural selection and evolution. Interestingly, Darwin’s cousin, Francis Galton, coined the term ‘eugenics’ shortly following Darwin’s discovery. This concept slowly gained momentum across Europe and North America, culminating in the perversion and misuse of scientific ideas to perpetrate the Holocaust. As World War II was waged and ended, the author explores the series of biological discoveries that identified that DNA is the carrier of hereditary information in humans. In 1953, the structure of the DNA molecule was solved in a story of intelligence, ambition and workplace hostility. In the 1970s, techniques such as DNA sequencing and cloning were invented, which revolutionized biology yet again. Genes were finally able to be mapped, and disease genes began to be identified and screened for. Later, this would play an important role for cancer detection. The reinforcement of previous work that genes could deviate from their ‘normal’ state into an alternative, often diseased state by acquiring mutations triggered the era of the Human Genome Project, an ambitious and mammoth-scale effort to understand the contents of our normal genetic makeup. Now, in the post-genome era, thousands of human genomes, both healthy and diseased have been sequenced and used to identify the genetic causes of disease. However, it is also being appreciated that the genomic sequence alone is not responsible for identifying and curing disease. The concept of epigenetics, which accounts for changes in the functioning of genes without any alteration of the DNA sequence itself, is also discussed as playing a role in normal human development as well as in disease.
What Mukherjee stresses throughout the book is the effect science and society have on each other. It was because mental illness was never truly understood that the mentally ill, the feeble and the weak were considered to be ‘genetically undesirable’ to society. What began as sterilization of the so-called genetically undesirable ended in outright extermination. In turn, scientific concepts and principles were used and misused to justify heinous crimes. Simultaneously, the historical and social circumstances of the time also informed, provoked or inspired scientific progress, whether intentionally or by accident.
In detailing the scientific process and circumstances that led to our understanding of the gene today, Mukherjee touches on many issues regarding our sense of identity, and discusses the ways that individuals are defined by and also independent from their genetics. In terms of evolution, we are the product of both our genetics as well as our environment. Understanding the interplay between the concepts of ‘nature’ and ‘nurture,’ has captured the minds of numerous scientists in the past and in the present, and this is a topic that will continue to be slowly unravelled going forward. In cancer, these interactions play a deeply pivotal role. In some cases, such patients with the inherited mutations BRCA1/2, there is a fairly high probability (~80%) of getting diagnosed with breast or ovarian cancer. However, many patients have other, less well understood genetic variations associated with these and other cancers, but it is much less clear how prone they actually are to developing the disease, and which genetic and external factors would influence this.
The book also addresses how our present understanding of genes has enabled us to create the technology to manipulate them, in order to study and counter disease. An extremely recent example of this is the multi-institutional study (published after the book came out) in which the authors successfully correct a pathogenic gene responsible for a heritable heart condition in pre-implantation human embryos, using cutting-edge gene editing techniques. However, this avenue of research has opened up several ethical decisions that will have to be debated and addressed, including where to draw the line in terms of genetic manipulation, and accounting for unforeseen side-effects of such invasive interventions.
Though containing a few inaccuracies that may be debated by scientists and historians, the book is an engaging and illuminating read. It masterfully captures the history of one of the most fundamental concepts in biology, one that has had an everlasting socio-political impact on the history of the world. The knowledge of the gene has been used both to fight disease as well as misused to commit mass murder. In understanding the gene, the unit of our inheritance as a species, perhaps we begin to learn what it means to be human.
Mukherjee S. The Gene: An Intimate History. Vintage (2017).
Ma H., Marti-Gutierrez N., Park S-W., Wu J., Lee Y., Suzuki K., Koski A., Ji D., Hayama T., Ahmed R., et al. Correction of a pathogenic gene mutation in human embryos. Nature (2017) | doi:10.1038/nature23305.