Why boys are more susceptible to autism than girls

Autism is four times more common in boys than in girls. Scientists now suspect testosterone. The hormone uses risk genes for autism.

Autism affects about 1.5 percent of all children. It is striking that boys are hit four times as often as girls. Until now, these differences could not be explained. Now there is evidence that the hormone testosterone might play a role. Scientists from Heidelberg University Hospital have demonstrated in human cells and brain regions that the male sex hormone testosterone significantly increases certain risk genes in the brain in the period before and after birth. Until now, only known is that defects in these specific genes are a strong risk factor for the development of neuronal developmental disorders.

Boys are at greater risk for autism

"Now we have a first indication why – at least with regard to an important group of the many risk genes – boys have a significantly higher risk of autism than girls," says senior author Prof. dr. Dr. med. Gudrun Rappold, director of the Department of Molecular Human Genetics.

These risk genes are SHANK1, 2 and 3 genes. The Heidelberg research group has been researching the SHANK genes for years, as defects in these parts of genetic information play an important role in the development of autism and other mental illnesses. ,

Testosterone activates SHANK genes

As the latest tests on the brains of young male mice have now shown, these genes are increasingly being converted into proteins and this is influenced by higher levels of the sex hormone testosterone. In the brains of male mice, which naturally have more testosterone in the blood and brain, the researchers also found significantly higher levels of Shank proteins than in women. "We expect that the larger amount of shaft protein in the male brain will increase the impact of defects in the SHANK genes and therefore lead to a higher risk of autism," explains Rappold.

The results of the work "Distinct Phenotypes of Shank2 Mouse Models Reflect Neuropsychiatric Spectrum Disorders or Human Patients with SHANK2 Variants" have just been published in the magazine "Frontiers in Molecular Neuroscience".

Autism manifests itself early

In autism, the development of nerve cells in the brain is disrupted. The symptoms are usually noticeable even in childhood and can vary greatly from patient to patient. Classically, autistic people have difficulty with social interaction, communication and perceptual processing and often exhibit intense, special interests. Nevertheless Many autistic people are very intelligent.