Why Autism Affects More Boys Than Girls: Study

Geneticists have long wondered why boys are more frequently born with autism than girls. It is also known that most female cases of autism are considered severe cases. Now, new research may help explain why autism seems so gender-selective.

A study published in the American Journal of Human Genetics, a Cell publication, sets out to explain the phenomenon geneticists have been calling a "female productive model" for years.

Researcher examined over 16,000 autistic study participants in all, selectively dividing this group by gender and the severity of their condition. The group proved to represent what is currently thought for the general population, that there are about seven males with mild autism for every one female with the same condition. As the severity of the autism increases, this gender gap quickly closes, with evidence that indicates that the number of most-severe autism cases in females is at least equal to the number of similar cases in males.

Analyzing genetic differences among genders, the researchers quickly found that males are more prone to common cases of autism because they can get autism from significantly smaller genetic components, compared to females, who on-average require a greater number of genetic mutations -- implying increased severity -- for autism to show.

Researchers concluded their study, suggesting that this decreased sensitivity to autism mutations in females might have everything to do with the X chromosome, where genetic information from double the x-chromosomes in females can lead to the developing brain overlooking mutations in genetic information that would normally lead to autism. Unfortunately for males, they receive only one x chromosome from their parents, increasingly the likelihood that mutations will effect a child's development considerably.

Of course, researchers are quick to point out that the study only focuses on proving the existence of greater genetic sensitivity to autism mutations in males. Further research will need to be done to determine the true cause of this bizarre phenomenon.

The study was published in the American Journal of Human Genetics on February 27.