Yale May Have Discovered Reason for the Female Protective Effect

Girls Require a Larger “Genetic Hit” than Boys to Develop ASD

A recent Yale-led study has discovered that autism develops in different areas of the brain for  girls than it does for boys. The researchers involved in this study also found that girls have a larger number of genetic mutations than boys suggesting that females need a larger “genetic hit” in order to develop the disorder. This discovery falls in line with the long recognized fact that boys are four times more likely than girls to receive an autism diagnosis. This imbalanced rate of autism between the sexes has been often referred to as the female protective effect, which has been poorly understood for decades. To shed more light on this effect, the researchers studied a balanced sample of boys and girls ages 8 to 17. This first  cohort was composed of 45 girls with autism and 47 boys with autism. The other cohort had 45 typically developing girls and 47 typically developing boys. By using a brain imaging technology called functional magnetic resonance imaging (MRI), the researchers studied how the brains of the youngsters with and without autism process human motion. Past studies, which almost exclusively relied on male subjects, found that a part of the brain called the posterior superior temporal sulcus is active in the social perception in typical children but less responsive for kids with autism. After using the MRI technology on both the study’s cohorts, the authors discovered the posterior superior temporal sulcus region constitutes a “neural signature” for autism in boys but not necessarily for girls. The neuroimaging showed that girls have a different area of the brain, called the striatum, that is more involved in processing human motion. The research team went one step further to probe into these sex based differences. After examining genetic data from the Simons Simplex Collection, they found that there was a larger number of copy number variations containing genes expressed in the same region of the brain, the striatum, for girls with autism. The study’s authors suggest that their findings may provide a clue into what is driving the female protective effect that makes girls less susceptible to autism. 

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