Scientists probe ‘dark genome’


Scientists are preparing to descend into the “dark genome” in search of previously unknown disease mutations.
A new technique called Orion has been developed that will help them expose harmful regions of DNA about which little is known.
Only 2% of the DNA making up the whole human genome is well understood by scientists. That is the fraction containing the 20,000 genes providing the coded instructions for building proteins.
The rest, known as the dark genome and once dismissed as non-coding junk DNA, remains a largely unsolved mystery.
The dark genome can be compared with the “dark web”, a region of the internet that is hard to access and often linked to criminal activity.
Like the dark web, it may conceal hidden dangers. Parts of the dark genome are known to turn genes on or off and could be strongly implicated in diseases such as cancer.
The dark genome may explain why the cause of conditions strongly suspected of having a genetic origin is identified in no more than one in three patients.
Orion was developed by United States scientists who compared the entire genomes of 1662 people with one another to identify stretches of DNA that vary little from person-to-person.
Because these regions are intolerant to change, it can be assumed they have important functions. Genetic faults in these regions are therefore more likely to cause diseases than mutations in less important parts of the genome.
“We anticipate that researchers will immediately start using Orion to help them find pathogenic mutations in patients in which previous sequencing efforts were negative,” Professor David Goldstein of Columbia University Medical Centre said. PA

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