Health & Medicine

New Genetics Study Reveals Which 'Letters' in the Human Genome are Functionally Important

Catherine Griffin
First Posted: Jan 26, 2015 09:47 AM EST

The human genome largely dictates what you're like as a person, and scientists are still unraveling the mysteries of this code to our existence. Now, though, they may have discovered a way to identify which letters in the human genome are functionally important.

There are three billion letters in the human genome. These letters encode genes, our hereditary information, and give cells instructions to use genes. Yet there's a large part of the genome that doesn't really do anything and is not devoted to encoding proteins.

"In model organisms, like yeast or flies, scientists often generate mutations to determine which letters in a DNA sequence are needed for a particular gene to function," said Adam Sipel, one of the researchers, in a news release. "We can't do that with humans. But when you think about it, nature has been doing a similar experiment on a very large scale as species evolve. Mutations occur across the genome at random, but important letters are retained by natural selection, while the rest are free to change with no adverse consequence to the organism."

Working off of this idea, the scientists began to work on the ENCODE Project, which provided the scientific community with information about genomic function over the last few years. Using the ENCODE data, the scientists examined combinations of biochemical tags. The combinations of these tags revealed several hundred different classes of sites within the genome each having a potentially different role in genomic activity.

Then, the scientists turned to their previously developed computation model, called INSIGHT. This allowed them to analyze how much the sequences in these classes had varied over both short and long periods of evolutionary time.

In the end, the researchers found that, at most, only about 7 percent of the letters in the genome are functionally important. The findings will allow researchers to isolate functionally important sequences in diseases much more rapidly. Most genome-wide studies implicate massive regions, containing tens of thousands of letters, associated with disease. This study, though, reveals which letters in these sequences are actually functional.

The findings are published in the journal Nature Genetics.

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