According to a new study the Biomedical Sciences Research Center (BSRC) “Alexander Fleming” in Vari, Greece, although humans evolutionarily split from our chimpanzee ancestors nearly seven million years ago, we are continuing to evolve. The experts identified 155 new genes within the human lineage which spontaneously arose from tiny sections of our DNA. Some of these “microgenes” date back to the ancient origins of mammals, with a few of them thought to be associated with human-specific diseases.
“This project started back in 2017 because I was interested in novel gene evolution and figuring out how these genes originate,” said study lead author Nikolaos Vakirlis, a researcher at BSRC. “It was put on ice for a few years, until another study got published that had some very interesting data, allowing us to get started on this work.”
By using the previously published dataset of functionally relevant new genes, the scientists created an ancestral evolutionary tree to compare humans to other vertebrate species. They tracked the relationship of these genes during evolution and discovered 155 that emerged from regions of unique DNA.
“It was quite exciting to be working in something so new,” says senior author Aoife McLysaght, a professor of Genetics and Molecular Evolution at Trinity College Dublin. “When you start getting into these small sizes of DNA, they’re really on the edge of what is interpretable from a genome sequence, and they’re in that zone where it’s hard to know if it is biologically meaningful.”
Among these 155 new genes, 44 were associated with growth defects in cell cultures, proving their importance in maintaining a healthy, living system. However, since these genes are human-specific, it is difficult to test directly their function. Yet, by examining patterns found within the DNA, the scientists found hints at what roles some of the genes may play in specific diseases.
Three of the newly identified genes had disease-associated DNA markers that pointed to connections to health conditions such as muscular dystrophy, retinitis pigmentosa, and the Alazami syndrome. Moreover, the researchers found a new gene associated with human heart tissue that most likely originated in humans and chimpanzees right after the evolutionary split from gorillas, an aspect showing how fast a gene can evolve to become essential for an organism.
“It will be very interesting in future studies to understand what these microgenes might do and whether they might be directly involved in any kind of disease,” says Vakirlis.
“These genes are convenient to ignore because they’re so difficult to study, but I think it’ll be increasingly recognized that they need to be looked at and considered. If we’re right in what we think we have here, there’s a lot more functionally relevant stuff hidden in the human genome,” concluded McLysaght.
The study is published in the journal Cell Reports.
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