More men than women have autism – now we may know why. Sex hormones regulate a gene linked with the condition, making it more likely that males will accumulate testosterone in the dangerous amounts that are thought to lead to autism.
For every female that has autism there are four males. To better understand this sex bias, Valerie Hu at the George Washington University Medical Center in Washington DC and colleagues studied a gene implicated in autism called retinoic acid-related orphan receptor-alpha (RORA). This gene controls a molecule that switches many subsequent genes on and off.
Previous research has shown that RORA is important for development of the cerebellum and that the brains of people with autism expressed less of it than normal. Mice that likewise express less RORA than normal display symptoms that resemble autism in humans, such as repetitive behaviours and deficits in spatial learning.