Researchers have said that women are able to carry higher levels of genetic defects without getting any brain development disorders like autism, supporting the possibility of a "female protective effect."
The study has provided clues as to why 50 percent more males typically have an intellectual disability than females and why boys are four times likelier to suffer from autism than girls, Discovery News reported.
Professor Evan Eichler of the University of Washington, USA, led a Swiss-U.S. team to look for genetic defects in 15,585 people diagnosed with a range of disorders believed to be due to faulty brain development - known as neurodevelopmental disorders.
The defects that were being looked for were large "copy number variants" (CNVs) - sections of chromosomes carrying perhaps a dozen genes either missing, or present as multiple copies.
Surprisingly, the females in the sample had more CNVs than the males, and despite both sexes in the study having neurodevelopmental disorders, the females were carrying a bigger "burden" of genetic damage.
The study has been published in The American Journal of Human Genetics.