A study conducted by researchers from Japan, China, Canada, and the U.S. found that DNA once considered "junk" makes up nearly half of the human genome.
This "junk" DNA comes from transposable elements belonging to the MER11 family. Researchers say that transposable elements function as genetic switches that control gene activity in specific cell types.
They also believe that gaining a clearer understanding of the human genome could help them make sense of genetic mutations linked to cancer and rare diseases. “Our genome was sequenced long ago, but the function of many of its parts remains unknown,” Dr. Inoue, one of the co-corresponding authors, said. “Transposable elements are thought to play important roles in genome evolution, and their significance is expected to become clearer as research continues to advance.”
The study also found that 8% of the human genome originates from viruses that infected our ancestors millions of years ago.
Researchers say the study provided them with a new approach to trace the evolutionary history of viral DNA. They suggest that viral sequences that were once overlooked may have important regulatory functions in gene expression.
“If we can clearly map what parts of our genome are specific to humans or primates, and what parts came from viruses, we’re one step closer to understanding what makes us human and how our DNA influences health and disease,” said Guillaume Bourque, one of the study’s lead authors and a professor in McGill’s Department of Human Genetics.
