Boys are at greater risk than girls for neurodevelopmental disorders like autism. The reason why has always been unknown, up to now. A large cohort study provides some compelling evidence supporting the “female protective model” which proposes that girls require more extreme genetic mutations than do boys in order to acquire neurodevelopmental disorders.
A difference in genders at the molecular level
“This is the first study that convincingly demonstrates a difference at the molecular level between boys and girls referred to the clinic for a developmental disability,” noted study author Sebastien Jacquemont of the University Hospital of Lausanne. “The study suggests that there is a different level of robustness in brain development, and females seem to have a clear advantage.”
Other studies inconclusive
Past studies investigating the reasons for gender bias have produced inconclusive results. Some speculate there is a social bias against boys, labelling them with autism or attention deficit disorder for displaying behaviors that may just be typical for boys but on the extreme. Other researchers have suggested there is a genetic susceptibility for boys which girls do not possess.
Female brains require more genetic variants than males
Jacquemont and his team looked at a cohort of 16,000 individuals with neurodevelopmental disorders and another cohort of 800 families affected by autism. They analyzed copy-number variants (CNVs) – variations in the number of copies of a gene – and single nucleotide variants (SNVs) - DNA sequence variations. They found that girls diagnosed with autistic spectrum disorder had more harmful CNVs and SNVs than boys. This suggests that the female brain requires more extreme genetic alterations than the male brain to produce a neurodevelopmental disorder.
Gender specific treatments may be useful
“Overall, females function a lot better than males with a similar mutation affecting brain development,” Jacquemont explained. “Our findings may lead to the development of more sensitive, gender-specific approaches for the diagnostic screening of neurodevelopmental disorders.”
Source: MedicalNewsToday, American Journal of Human Genetics
Photo by Picture Youth at flickr.com
