A study led by Dr. Eli Hatchwell of Stony Brook University Medical Center in New York has found that disruption of a gene called contactin 4 prevents the brain from making proper networks. Two copies of the gene are required for proper functioning but some children have either three copies or one copy. Dr. Hatchwell estimates that contactin 4 gene disruption may be involved in as many as 2.5 percent of autism cases:
"Generally the mistake that people make is they are looking for one unifying cause for autism, and there is no such thing and there never will be," Hatchwell said in a telephone interview.....
"Autism is a syndrome. These individuals have all been grouped together as having the same thing. There will be many, many dozens if not hundreds of different causes," he said.
Contactin 4 is involved in the development of axons, which are the long strings that connect one neuron to another. Other disruptions of this gene are known to cause developmental delay and mental retardation.autism