Geneticists at the University of Washington have discovered that a region of the human genome associated with autism, schizophrenia, and other disorders evolved recently, over the past 250,000 years. Their findings were presented at the American Society of Human Genetics (ASHG) 2014 Annual Meeting in San Diego.
Researchers studied the genomes of 2,551 humans, 86 apes, one Neanderthal, and one Denisovan. They found that a region of human chromosome 16, known as 16p11.2, is prone to genetic modifications involving duplication or deletion of certain strands of DNA. These modifications have been linked to several diseases, including autism. Researchers also found that these modifications were not present in the non-human DNA, suggesting that these gene mutations originated with human beings.
Author Xander Nuttle, B.S., B.S.E, graduate student in the Department of Genome Sciences at the University of Washington, said, “When we compared the genomes of apes and humans, we found that the humans had evolved complex structural changes at 16p11.2 associated with deletions and duplications that often result in autism. The findings suggest that these changes emerged relatively recently and are unique to humans.”
While this genetic variation has made humans more susceptible to disease, researchers also believe it has contributed to the formation of novel genes, such as BOLA2, which is thought to be important in cell reproduction. Humans have between three and 14 copies of BOLA2, with an average of six, while apes, Neanderthals and Denisovan only have two.
While gene variations in the 16p11.2 region are linked to various diseases, severity of symptoms can range from severe to mild between different individuals. Researchers believe this may be due to individual differences in how the region is organized, including the number of copies of BOLA2, and exact locations where deletions and duplications start and stop. The team plans to follow up on this by studying DNA and medical data from over 125 individuals with deletions and/or duplications at 16p11.2.
“We believe this work will lead to new insights about the genetic underpinnings of autism and other conditions associated with 16p11.2 deletions and duplications, potentially paving the way for more specific diagnostics and treatments for patients in the future.”