DNA at 60

On April 25, 1953, Francis Crick and James Watson published a one-page paper that many believed would revolutionise biological research. Building on the work of Rosalind Franklin and Maurice Wilkins, they had discovered DNAs double-helix structure, providing the first glimpse into how organisms inherit and store biological information. But, 60 years later, has their discovery really had the transformative impact that the world expected?

The media marked the publications 60th anniversary with much fanfare, hailing the breakthrough that ushered in the age of genetics, and calling it one of the most important scientific discoveries of all time. The British newspaper The Guardianfeatured the headline, Happy Birthday, DNA! The golden moment that changed us all.

To some extent, they are right. The finding forms the basis of genetics and has opened up promising new research areas, such as synthetic biology, in which biological systems are created or modified to perform specific functions. Likewise, it has facilitated important innovations, such as pharmacogenetic cancer treatment, in which drugs target specific genetic defects within cancer cells.

Moreover, DNA has acquired a certain mystique in popular culture. According to Dorothy Nelkin and Susan Lindee, it has become a sacred entity - the modern equivalent of the Christian soul, an individuals essence. While some forms of biological determinism, such as the belief that race or gender dictates a persons destiny, have been widely rejected, the idea that a person can be genetically predisposed, say, to get into debt, become a ruthless dictator, or vote regularly in elections remains socially acceptable.

But, almost from the beginning -and most intensely since 1971, when Time magazine published a special section entitled, The New Genetics: Man into Superman - science and society alike have tended to overestimate the impact of genetics. When the Human Genome Project published the first draft of the fully sequenced human genome in 2000, Henry Gee, an editor of the journal Nature, predicted that scientists would be able to alter entire organisms out of all recognition to suit our needs and tastes by 2099. We will have extra limbs, if we want them, he asserted , maybe even wings to fly.

Thirteen years later, Gees prediction looks increasingly unlikely, with the Human Genome Project so far having failed to meet expectations. Indeed, in 2010, the science writer Nicholas Wade lamented that , a decade after the project was launched, geneticists were almost back to square one in knowing where to look for the roots of common disease.

For example, a 12-year study of 19,000 white American women found that 101 genetic markers that had been statistically linked to heart disease had no predictive value. Self-reported family histories, by contrast, proved very accurate in predicting the disease.

In fact, most diseases are not caused by single genes. As a result, after a few early successes with atypical single-gene disorders such as Huntingtons disease, progress has stalled. Common variants typically explain a small fraction of genetic risk.

Genetics has been a source of particularly high hopes when it comes to cancer treatment. Between 1962 and 1985, cancer-related deaths in the US rose by 8.7 percent, despite the use of aggressive chemotherapy drugs and radiation therapy, highlighting the dangers of a one-size-fits-all approach to treatment. An understanding of the genetic determinants of patients therapeutic response, it was believed, would enable doctors to develop individualised treatment programmes, sparing more responsive patients from harmful overtreatment.

But patients are not the only variable. Cancer, too, is heterogeneous, even in patients with the same diagnosis. After sequencing the entire genomes of 50 patients breast cancer tumors, researchers found that only 10 percent of the tumours had more than three mutations in common. According to a recent study mapping genetic mutations in 2,000 tumours, breast cancer can actually be divided into ten subgroups.

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DNA at 60