Gene Study Explains Why More Boys than Girls have Autism
For years, statistics have revealed that boys are more likely to be diagnosed with autism spectrum disorders (ASDs). ASDs are a group of developmental disorders that are characterized by social, communication and behavioral challenges. In a new study, researchers analyzed DNA in order to examine why boys have a higher incidence rate of ASDs. The researcher concluded that girls appear to be better capable of tolerating certain mutations than boys
"Girls tolerate neurodevelopmental mutations more than boys do. This is really what the study shows," said study author Sebastien Jacquemont, an assistant professor of genetic medicine at the University Hospital of Lausanne, in Switzerland, reported by WebMD. "To push a girl over the threshold for autism or any of these neurodevelopmental disorders, it takes more of these mutations. It's about resilience to genetic insult."
For this study, researchers from Switzerland and scientists from the University of Washington School of Medicine received around 16,000 DNA samples and sequencing data sets to analyze. The samples were from people with neurodevelopmental disorders. On top of these samples, the researchers also analyzed genetic data provided from nearly 800 families that had ASDs.
In the DNA, the researchers specifically looked at copy-number variants (CNVs) and single-nucleotide variants (SNVs). The researchers found that girls with a type of neurodevelopmental disorder had more CNVs than males who had the same condition. In terms of autism, girls had more harmful SNVs than males with autism did.
"If we divide [the cohort] into females and males, and look at really big mutations, do we see a difference between boys and girls in terms of frequency?" study author, Evan Eichler said reported by FOX News. "The answer was, unequivocally, yes. Girls tend to have more of these than boys. Boys have fewer than females."
According to the United States Centers for Disease Control and Prevention (CDC), boys have a one in 52 chance of being diagnosed with ASDs. For girls, that rate is one in 252.
"There's a well-known disparity when it comes to developmental disorders between boys and girls, and it's been puzzling," Jacquemont added. "And there have been quite a bit of papers trying to investigate this bias that we've seen in the clinic."
The study was published in the American Journal of Human Genetics.