Epigenome, the largest-ever map of molecular switches that affect genes was unveiled by a consortium of scientists on Wednesday. It is a tool which helps to understand how diseases are caused. The work, assembled by scientific publishing house Nature, is the most ambitious look yet at epigenetics, considered one of medicine's most promising frontiers.
Epigenomes are chemical tags attached to DNA, the inherited genetic code for making and sustaining life.
They do not alter genes, but influence whether specific genes are turned on or off, which in turn determines how cells look and act.
There is more and more evidence that epigenomes play a role in conditions such as cancer, Alzheimer's, autism and heart disease. And they appear to be disrupted by ageing and by lifestyle choices -- smoking and diet, for instance.
The news papers described the epigenomes of 111 different types of cell, including brain, muscle, liver, skin and foetal cells.
They add to a previous haul, published in 2012, of 16. The researchers said the database would boost understanding of how the genetic code -- which with few exceptions is the same in every cell -- is expressed so differently.
- 'Major advance' -
Only about 1.5 percent of the genome comprises genes. The rest was once dismissed as junk, but today much of it is deemed to be functional and perhaps even crucial.
"This represents a major advance in the ongoing effort to understand how the three billion letters of an individual's DNA instruction book are able to instruct vastly different molecular activities," said Francis Collins, head of the US National Institutes of Health (NIH) which funded the $300-million (264-million-euro) Roadmap Epigenomics Programme.
In other studies also published by Nature and its specialist sibling journals, researchers reported on the potential for adding epigenetic profiling to existing tools for exploring disease.
In one paper, researchers from Brigham and Women's Hospital at Harvard Medical School in Massachusetts found they could use a cancer cell's unique genetic signature to identify the type of cell where the cancer originated. The finding could be important in treating metastatic cancer, which spreads to different tissues.
In another paper, scientists at Imperial College London identified 34 genes that play a part in asthma and other allergic diseases -- a tempting target for drug designers.
"Our pioneering approach, using epigenetics, allowed us to obtain insights that we weren't able to get from traditional genetics," said William Cookson, a professor at Imperial College's National Heart and Lung Institute.
"It isn't just the genetic code that can influence disease, and DNA sequencing can only take you so far," Cookson said in a statement. "Our study shows that modifications on top of the DNA that control how genes are read may be even more important."