Scientists have found an explanation for a higher risk of autism in a boy. / table, stock.adobe.com
Heidelberg – Autism occurs 4 times more often with a boy than a girl. Scientists from the Department of Molecular Genetics at the University Hospital in Heidelberg have found an explanation: studies on human cells and brain parts of mice have shown that male sex hormone testosterone significantly activates certain genes of risk in the brain before and after birth. The results were in Boundaries in molecular neuroscience published (2018; doi: 10.3389 / fnmol.2018.00337).
So far, it is only known that defects in these specific genomes are strong risk factors for the development of neuronal developmental disorders. New results indicate that these genetic defects can have a greater impact on the minds of the male than the female individuals.
"Now we have the first indicator why – at least in relation to an important group of many risk genes – boys have a significantly higher risk of autism than a girl," says senior author Gudrun Rappold, director of the Department of Molecular Genetics.
Tests of their group showed that certain genes SHANK 1, 2, and 3 were increasingly translated into proteins in the young male brain of mice and are affected by higher levels of sex hormone testosterone. The Heidelberg research group has been researching SHANK genes for years, because defects in these genetic information sections play an important role in the development of autism and other mental illnesses.
More testosterone – more protein proteins
For tests, the team used the cell culture of childhood brain tumors (neuroblastomas) as a model for the development of nerve cells. Scientists have discovered in these cells that SHANK gene activation depends on binding testosterone to the androgen receptor. When this receptor is blocked, there is a strong activation of risk genes. "We could confirm this in studies in the areas of the brain of young mice in which this androgen receptor is not formed: they were activated considerably weaker than control animals with intact receptors," explains Simone Berkel, this study along with Dr. Ahmed Eltokhi, conducted.
The researchers also studied the amount of protein protein in the brain of young male and female mice before and after birth. In male animals, which naturally have more testosterone in the blood and brain, significantly higher levels of Shank protein were found than in women. "We believe that a higher amount of protein protein in the male brain increases the" blows "of defects in the SHANK gene and therefore leads to a greater risk of autism," concluded Rappold.
on the subject
In autism, the development of nerve cells in the brain is disturbed. One in 68 children (about 1.5%) is affected. Typical symptoms are noticeable early, so the diagnosis is usually done 3 years ago. Autistic people have difficulties in social interaction, in communication and perceptual processing, and often show intense, special interests and abilities, as well as repetitive and narrow (restrictive) patterns of behavior. However, these characteristics of autistic behavior can vary greatly from patient to patient – this is why autism is concerned. © IDV / energy / aerzteblatt.de