A massive DNA database has generated a map of the genetic switches which impact everything from hair loss to cancer and opened the door to revolutionary treatments for a host of deadly diseases, researchers said.

This is a major step towards understanding the wiring diagram of a human being

“This is a major step towards understanding the wiring diagram of a human being,” said lead researcher Michael Snyder of Stanford University.

The Encyclopaedia of DNA Elements – or Encode – has enabled scientists to assign specific biological functions for 80 per cent of the human genome and has helped explain how genetic variants affect a person’s susceptibility to disease.

It also exposed previously hidden connections between seemingly unrelated diseases such as asthma, lupus and multiple sclerosis, which were found to be linked to specific genetic regulatory codes for proteins that regulate the immune system.

A key insight revealed in a host of papers published in the journals Nature, Science and Cell is that many diseases result from changes in when, where and how a gene switches on or off rather than a change to the gene itself.

“Genes occupy only a tiny fraction of the genome and most efforts to map the genetic causes of disease were frustrated by signals that pointed away from genes,” said co-author John Stamatoyannoupoulos, a researcher at the University of Washington.

“Now we know that these efforts were not in vain and that the signals were in fact pointing to the genome’s ‘operatingsystem’.”

Another significant finding is that this blueprint of genetic switches can be used to pinpoint cell types that play a role in specific diseases without needing to understand how the disease actually works.

For instance, it took researchers decades to link a set of immune cells with the inflammatory bowel disease Crohn’s.

The Encode data was able to swiftly identify that the genetic variants associated with Crohn’s were concentrated in that subset of cells.