Sébastien Jacquemont of the University Hospital of Lausanne in Switzerland and Evan Eichler of the University of Washington School of Medicine reported the first evidence of genetic differences that explain why more males have autism and other neurodegenerative conditions than females in the Feb. 27, 2014, issue of the American Journal of Human Genetics.
The researchers examined the gene structure of 16,000 individuals with neurodevelopmental disorders and the genetic code of 800 families with autism spectrum disorder.
The scientists found that females have the ability to compensate for more individual variations in the number of copies of a particular gene and more DNA sequence variations involving a single nucleotide than males.
The female brain requires a much larger number of genetic defects to produce the symptoms of autism or other neurodegenerative diseases than the male brain.
This is the first large investigation that proves there is a difference in the brains and genes of males and females that produces a higher level of autism and neurodegenerative diseases in males.
"Overall, females function a lot better than males with a similar mutation affecting brain development," Jacquemont says.
The discovery may lead to new treatments for autism and neurodegenerative diseases based on sexual differences and chromosomal differences in males and females.