Modern humans split evolutionarily from our chimpanzee ancestors nearly 7 million years ago, but we continue to evolve. We have identified 155 new genes within the human lineage that have arisen spontaneously from small sections of our DNA. Some of these genes date back to ancient mammalian origins, with some of these “microgenes” predicted to be associated with specific human diseases. The studio was published in the magazine Cell reports.
‘This project started in 2017 because I was interested in new genetic evolution and discovering the origin of these genes,’ said first author Nikolaos Vakirlis, a scientist at the Alexander Fleming Biomedical Sciences Research Center in Vari, Greece. “It sat for a few years, until another study came out with some very interesting data, which allowed us to start this work.”
Taking the previously published dataset of functionally relevant new genes, the researchers created an ancestral tree by comparing humans with other vertebrate species. They traced the relationship of these genes through evolution and found 155 of them originated from regions of unique DNA. New genes can arise from duplication events already existing in the genome; however, these genes came from scratch.
‘It was very exciting to work on something so new,’ said senior author Aoife McLysaght, a scientist at Trinity College Dublin, Ireland. “When you start to get into these small dimensions of DNA, I’m really at the edge of what’s interpretable from a genome sequence, and I’m in that area where it’s hard to know if it’s biologically significant.”
Other hidden things
Of these 155 new genes, 44 are associated with growth defects in cell cultures, demonstrating the importance of these genes in maintaining a healthy and alive system. Since these genes are specific to humans, this makes direct testing difficult. Researchers must look for another way to explore the effects these new genes might have on the body. Vakirlis and her team looked at patterns found in the DNA that could indicate whether these genes play a role in specific diseases.
Three of these 155 new genes have disease-associated DNA markers that indicate connections to diseases such as muscular dystrophy, retinitis pigmentosa and Alazami syndrome. The researchers also discovered a new gene associated with human heart tissue. This gene emerged in humans and chimpanzees shortly after the gorilla split and shows how quickly a gene can evolve to become essential to the body.
“It will be very interesting in future studies to understand what these microgenes can do and whether they can be directly involved in some kind of disease,” Vakirlis noted.
“It’s convenient to ignore these genes because they are so difficult to study, but I think there will increasingly be recognition that they need to be looked into and considered,” McLysaght said. “If we’re right about what we think we have here, there’s a lot more functionally relevant material hidden away in the human genome.”
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