Causes: Is Asperger's Syndrome Genetic?

Courtesy of the National Institute of Neurological Disorders and Stroke

Twin and family studies suggest there is a genetic vulnerability to Aspergers Syndrome and the other ASDs, but a specific gene for AS hasn’t been identified. It is likely that multiple genes cause Aspergers, since the symptoms and the severity of symptoms vary so widely among individuals.

Researchers recently identified an association between certain behavioral traits (the insistence on strict routines and repetitive behavior) in a group of children with autism and a specific gene – GABRB3. Another study discovered a strong association between autism and the mutation of a gene the researchers call ENGRAILED 2. Additional evidence for the link between inheritable genetic mutations and AS is seen in the higher incidence of family members of children with an ASD who have similar behavioral symptoms, but in a more limited form. For example they may have mild social, language, or reading problems.

Current research points to structural abnormalities in the brain as a cause of AS. These abnormalities impact neural circuits that control thought and behavior. Researchers think that gene/environment interactions cause some genes to turn on or turn off, or turn on too much or too little in the wrong places, and this interferes with the normal migration and wiring of embryonic brain cells during early development.

Researchers at the University of California , supported in part by the National Institutes of Health, have proposed that Asperger's Syndrome stems from abnormal changes that happen during critical stages of fetal development. Defects in the genes that control and regulate normal brain growth create abnormal growth patterns, which cause overgrowth in some brain structures and reduced growth, or excessive cell loss, in others.

Using advanced brain imaging techniques, scientists have revealed structural and functional differences in specific brain regions between the brains of normal versus AS children. One study found a lack of activity in the frontal lobe of AS children when asked to respond to tasks that required them to use their judgment. Another found differences in brain activity when children were asked to respond to facial expressions. Other methods of investigating brain function have revealed abnormal levels of particular proteins in the brains of adults with Asperger's Syndrome, which correlate with obsessive and repetitive behaviors.