A puzzle posed by segments of 'dark matter' in genomes — long, winding strands of DNA with no obvious functions — has teased scientists for more than a decade. Now, a team has finally solved the riddle.

The conundrum has centred on DNA sequences that do not encode proteins, and yet remain identical across a broad range of animals. By deleting some of these ‘ultraconserved elements’, researchers have found that these sequences guide brain development by fine-tuning the expression of protein-coding genes.

The results1, published on 18 January in Cell, might help researchers to better understand neurological diseases such as Alzheimer’s. They also validate the hypotheses of scientists who have speculated that all ultraconserved elements are vital to life — despite the fact that researchers knew very little about their functions.

“People told us we should have waited to publish until we knew what they did. Now I’m like, dude, it took 14 years to figure this out,” says Gill Bejerano, a genomicist at Stanford University in California, who described ultraconserved elements in 20042.

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