The majority of evidence has linked autism to a genetic cause. Xander Nuttle from the University of Washington and colleagues from the University of Lausanne in Switzerland and the University of Bari in Italy are the first to determine the time frame of the origin of the genetic dysfunctions that cause autism.
The researchers compared the genome sequences of apes, human, Neanderthals, and Denisovans. The group found that the genetic changes that produce autism developed about 250,000 years ago in humans. The genetic modifications that produce autism are completely linked to modern humans and have no counterpart in ancient human ancestors or apes.
The research focused on the section of chromosome 16 called the 16p11.2 region. This region is known to be a center of gene deletion and duplication in both humans. Part of the genetic code in this area is repeated a variable number of times in different people and that duplication can produce autism, schizophrenia, and other conditions.
The researchers also found a gene produced in humans that is directly related to the potential for a person to have autism. The gene is named BOLA2 and is thought to play a major role in cell reproduction. Apes, Neanderthals, and Denisovans have two copies of the BOLA2 gene. Modern humans can have between three and 14 copies of the gene. The average number of copies of BOLA2 in humans is six based on an analysis of 2,551 living people.
The researchers propose that the severity of autism symptoms and behaviors may be linked to the number of duplications of the BOLA2 gene in the 16p11.2 region. The scientists are analyzing the genetic structure of 125 people that have autism to determine the correlation between genetics and the severity of autism. The potential for isolating the gene structure that causes autism and selectively removing the duplications is a real potential for curing autism.
