Going up the double helix

Priyanka Singh

The Mitochondrial Eve, the mother of mothers, lived in Africa about 2,00,000 years ago. All human matrilineal lineage can be traced back to her. If there were a ‘book of man’, it would comprise 3,088,286,401 letters of DNA, with only four letters, AGCT (chemical bases), over 15 lakh pages — 66 times the size of the Encyclopaedia Britannica, and 300 crore base pairs of DNA. There is no strength in numbers; it is true of genes too. It is not how many genes make up an organism, but the ‘sophistication’ of gene networks that makes the difference. Else we would be a squiggly worm, or worse, breakfast cereal.

The book reads like science fiction, only it isn’t.

Consider this: During respiration, sugar combines with oxygen to produce carbon dioxide and energy. None of these reactions occur spontaneously, if they did, our bodies would be alight with the ‘smell of flambéed sugar’!

And this: If haemoglobin’s capacity to deliver oxygen to distant sites is cut off, we would be cold and small, much like insects.

A human body has 46 chromosomes and 21000-odd genes. Each time a cell divides, it makes a copy of every gene — elementary science. Making every single biological and physiological process possible, the genes reside on the genome, a giant factory — an owner’s manual that comes with how a product ought to function and repair itself; influencing human identity, sexuality, even temperament.

From Aristotle’s time, till now, there have been frenetic attempts to chase the truth of heredity; of the origin of humans. What makes us what we are? How are genes regulated? How does an embryo understand embedded instructions?

Over time, genetics evolved, rapidly followed by eugenics; meant to alleviate suffering by detecting disease-causing genes and manipulating them. Around this time, confinement centres came up in America where ‘feeble-minded’ men and women were sterilised. This was also when Better Babies contests were held as support to eugenics.

What followed in Nazi Germany shook the conscience of the movement. Expressed variously as ‘racial hygiene’, ‘genetic cleansing’, purity of race, the experiments under Josef Mengele [I was Doctor Mengele’s Assistant by Miklos Nyiszli is a chilling account] led to dreadful consequences. Action T4 would see the liquidation of a quarter of a million humans. The global eugenic movement came to a painful, crushing halt.

Nobel laureate Hermann Muller backed genetics to benefit humankind, but warned it could only happen in a society that had achieved ‘radical equality’. “Eugenics couldn’t be a prelude to equality… it would degenerate into yet another mechanism by which the powerful could control the weak,” he declared.

Between 1970 and 1980, mutant hunters took charge as gene manipulators and decoders. By 1998, 12,000 gene variants were linked to traits and disorders. One gene could cause several diseases; one disease could be a result of many genes.

The Human Genome Project began the mapping of genes in the 1990s. This would be a turning point in identifying genes linked to familial diseases like breast cancer, schizophrenia and Alzheimer’s. Gene cloning came with a clause. The moral implications were deliberated at Asilomar II conference, where self-regulation was a major takeaway.

A child can’t be denied the right to be born free of genetic anomalies, but once the genes are controlled, ‘no beliefs, no values, no institutions are safe’. Things could go horribly wrong. And they did. In 1999, 18-year-old Jesse Gelsinger, suffering from OTC enzyme deficiency, was the first to undergo a clinical trial for gene therapy. The ‘hurriedly designed’, ‘badly monitored’ trial caused his death — a solemn, cautionary tale of scientific overreach.

From experiments with pea hybrids and fruit flies, modern geneticists have come a long way. The baton has been passed: it’s over to the next generation of scientists.

A cancer geneticist and stem cell biologist, Mukherjee — in a parallel story — talks of a ‘madness’ strain running in his family for two generations; and his fears. Is he a carrier? Could he be next?

An exposition on all things gene, the book is dense and immensely enlightening. A layman can make sense of it, even though the medical jargon intimidates and some sections get technical as you read about the cutting-edge work of geneticists, riddled with urgency. The distance from mice to men must be covered with fleeting speed and accuracy, with no room for mistakes.

‘For genes humans are nothing but carriers,’ says Japanese writer Haruki Murakami, ‘Genes don’t think about what constitutes good or evil. They don’t care if we are happy...We’re just means to an end for them.’

We are the sum total of our genes: it’s as simple as that, and as complex.