CAUSES OF AUTISM
Autism hits 1 out of 150 children under the age of three. It is now postulated that genes lose regulation because of disturbed synaptic connections caused by early life environment and experiences.
Prominent features of the illness include repetion and stereotyped and obsessive compulsive like behavior. These are often accompanied by seizures and disturbed sleep patterns.
There seems to b a substantial genetic component. Many underlying genes are involved. Discrete changes in DNA sequence is identified in autism but rarely replicated. There are small losses and gains of DNA (7-12) called copy number variations.
Everyone has this common genetic variation and it can arise from a sporadic event. It is difficult today to interpret the observed copy number variation. This major category of genetic risk is implicated in up to 20% of the cases of autism.
Several of these genes affected by deletions are regulated by neuronal activity. Since the brain continues to grow after birth, experiences and environment play a big role in brain development. Connections between neurons (synapses) mature partly by experience dependent neuronal activity and the genes that accompany it.
If the genes are disrupted by mutation or copy number variation, it will disturb these neuronal connections.
This theory that genes lose regulation when their connections are disturbed because of early life environment and experiences still requires further research to validate this theory.
Meanwhile, the life environment and experiences that trigger the disruption of genes will be argued for some time until these experiences are truly isolated.
Source: Science, July 11, 200
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