Year in review: Epigenome makes its debut

Chemical modifications bring DNA to life

EPIGENOME DEBUT  Chemical modifications to DNA and histones can influence how genes are turned on and off during development and in health and disease. In 2015, scientists cataloged where these marks and others are made in human DNA.

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In a landmark event more than a decade ago, geneticists unveiled the human genetic instruction book. This year, the book was turned into a movie adaptation in 3-D: Researchers cataloged how chemical modifications fold, compress and unwind the static DNA over time and how those modifications control when genes are on or off. 

The crew of researchers involved in the Roadmap Epigenomics Project premiered their findings in more than 20 scientific papers published in February (SN: 3/21/15, p. 6).

It was a blockbuster effort that would never make it in Hollywood. For one thing, it largely ignores the stars of the genome, the genes, and instead focuses on a dizzying cast of background characters known as epigenetic marks. The researchers cataloged these marks — chemical modifications either of DNA itself or proteins called histones — in more than 100 types of human cells. The epic effort revealed that gene variants associated with Alzheimer’s disease are more active in immune cells in the brain than in nerve cells as researchers had assumed. Another plot twist: Tightly packed areas of the genome are more vulnerable to cancer-causing mutations.

Like a classic movie in which viewers notice something new with each showing, researchers using data from this project and other efforts to view the genome in 3-D have made startling discoveries (SN: 9/5/15, p. 18). For instance, researchers found that a gene called FTO, thought to be a major genetic contributor to obesity, isn’t involved in fat production. Instead, a genetic variant hiding in the gene’s vicinity actually determines what type of fat the body builds (SN: 9/19/15, p. 6). Disorganized DNA may be a cause of aging, researchers also discovered (see “Not all bodies act their age“).

The epigenome movie is sure to spark a series of sequels, each one revealing deeper secrets about human biology and suggesting new ways to improve human health.

GAME OF TAGS By mapping epigenetic marks in 111 types of tissues and cells (some shown here), researchers gained new insights into how the body is built and maintained. Some of these details aren’t captured in studies of DNA alone. Roadmap Epigenomics Consortium

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