Scientists have discovered a second code that’s been hiding within DNA that could change the way genetic instructions are read.

A team of University of Washington researchers discovered the secondary code, which was published Friday in Science, and could help scientists better understand both disease and health.

DNA, or deoxyribonucleic acid, is present in the cells of all humans and most other living organisms, and scientists have assumed since the 1960s that it was used exclusively to write information about proteins.

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But researchers discovered that information was superimposed over another set of instructions that cells use to control genes.

“For over 40 years we have assumed that DNA changes affecting the genetic code solely impact how proteins are made,” said Dr. James Stamatoyannopoulos, who led the UW team. “Now we know that this basic assumption about reading the human genome missed half of the picture. These new findings highlight that DNA is an incredibly powerful information storage device, which nature has fully exploited in unexpected ways.”

The researchers discovered that some codons, part of the 64-letter alphabet which makes up the genetic code, can have two meanings – one related to protein sequence and another related to gene control.

These duons apparently evolved together, researchers said, and the gene control instructions appear to stabilize beneficial features of proteins and how they’re made.

The discovery has major implications for the way scientists and physicians interpret genomes and will likely change the way diseases are diagnosed and treated.

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“The fact that the genetic code can simultaneously write two kinds of information means that many DNA changes that appear to alter protein sequences may actually cause disease by disrupting gene control programs or even both mechanisms simultaneously,” said Stamatoyannopoulos.

[Image: A scientist examines an image of double-helix DNA via Shutterstock]