Autism spectrum disorders (ASD) or autism are now known to be multifactorial in origin, meaning that they occur in individuals who are genetically predisposed after exposure to one or more as yet unknown environmental factors.
Causes of Autism
Autism Spectrum Disorder (ASD) is now known to be multifactorial, meaning that it occurs in individuals who are genetically predisposed after exposure to one or more environmental factors.
Environmental factors include use of certain medications during pregnancy, prematurity or lack of oxygen at birth. To date, however, solid scientific evidence has ruled out the role of vaccines in the development of autism.
Epidemiological studies show a ratio of 3 affected boys to 1 girl.
The genetic component is now confirmed by the high concordance of autism in monozygotic twins. It is also known that the risk of having a child with ASD is 50 to 100 times higher in the sibling of an autistic person.
Genetics in Autism
There are now several hundred genes known to predispose individuals to ASD, genetic variants that increase the risk of developing the disease in individuals who carry them. These variants are neither necessary nor sufficient to develop ASD, i.e. a person with a given variant may not have ASD and a person with autism may not have ASD.
The identified susceptibility genes are involved primarily in neurotransmission (the passage of information from one neuron to another) in synapse formation (the sites of passage of neurotransmission) and more generally in brain development.
At Paris Brain Institute: Clinician scientists from Paris Brain Institute et du Centre du Neurodéveloppement Adulte (CNA, unit of the Adult Psychiatry Service of the Hôpital Pitié Salpêtrière) are setting up a study on neuroanatomical and functional markers of the autism spectrum in adult women. report no autistic traits.
Certain brain abnormalities have been identified in autistic persons and are localized in the ventricles (dilation), in the cerebellar vermis, in the nuclei of the brainstem or in the hippocampus.
The CHD8 gene is one of the predisposing genes for autism that gives rise to a high risk of developing the disease. Carlos PARRAS, Inserm researcher in the team led by Bassem HASSAN, showed in 2018 the role of the protein encoded by this gene in differentiating oligodendrocytes. These central nervous system cells have two essential roles:
- Myelination, the formation of an insulating and protective sheath of neurons, myelin that facilitates the passage of the nerve message
- The supply of energy to neurons for the optimal functioning of these cells
The results of this work show an important role for oligodendrocytes in the brain abnormalities that cause autism spectrum disorders.
At Paris Brain Institute
Clinician scientists from the Institute of Brain and Centre for Adult Neurodevelopment (CNA, unit of the Department of Adult Psychiatry at Pitié Salpêtrière Hospital) are setting up a study on neuroanatomical and functional markers of the autism spectrum in adult women.
This project will compare MRI data from young women with autistic traits without ASD diagnosis to those with autism and those without autistic traits.
