Scientists have found an explanation for the higher risk of autism in boys. / mizina, stock.adobe.com
Heidelberg – Autism occurs 4 times more often in boys than in girls. For the first time, scientists from the Department of Molecular Human Genetics at Heidelberg University Hospital found an explanation: their studies in human brain and mouse regions showed that male sex hormone testosterone significantly activates certain brain and brain-related genes in the brain before and after birth. The results were at The Border in Molecular Neuroscience published (2018; doi: 10.3389 / fnmol.2018.00337).
So far, it is only known that defects in these particular genes are a powerful risk factor for the development of neuronal developmental disorders. New results show that these genetic defects may have a greater effect on the brains of men than women.
"Now we have a first indication because – at least in relation to an important group of many risk genes – boys have a significantly higher risk of autism than girls," says senior author Gudrun Rappold, Director of the Department of Molecular Human Genetics.
Their team trials have shown that in the young brain of male mice certain genes called SHANK 1, 2 and 3 are becoming increasingly protein-bound and that this is affected by higher levels of sex hormone testosterone. The Heidelberg research team has been researching the SHANK genes for years because defects in these genetic information segments play an important role in the development of autism and other mental illnesses.
More Testosterone – More Strain Protein
For the tests, the group used cell culture of childhood cancerous tumors (neuroblastoma) as a model of nerve cell growth. Scientists have discovered in these cells that activation of SHANK genes depends on the binding of testosterone to an androgen receptor. When this receptor was blocked, strong activation of the risk genes disappeared. "We were able to confirm this in studies in brain regions of young mice in which this androgen receptor was not formed: they were significantly weaker than in control animals with intact receptors," explains Simone Berkel, student Ahmed Eltokhi is being held.
Researchers also studied the amount of stem protein in the brain of young male and female mice before and after birth. In male animals, which of course have more testosterone in the blood and the brain, significantly higher levels of Shank proteins were found than in females. "We believe that the largest amount of stem protein in the male brain increases the" perforation "of defects in the SHANK genes and therefore leads to a higher risk of autism," Rappold concluded.
on the subject
In autism, the development of nerve cells in the brain is disturbed. One of the 68 children (approximately 1.5%) is affected. Typical symptoms are evident early, so diagnosis is usually made before the third year of life. Autistic people have difficulties in social interaction, communication and perceptual processing, and often show strong, special interests and abilities, as well as recurring and narrow (restrictive) patterns of behavior. However, these features of autistic behavior can vary widely from patient to patient – one of them talking about a range of autism. © IDW / energy / aerzteblatt.de