New evidence is found for the idea that multiple genes contribute to autism. "It is highly unlikely that there is only one gene responsible for autism," said Gerard Schellenberg, researcher at the Puget Sound Veterans Affairs Medical Center and research professor of medicine at the University of Washington. "There may be four to six major genes and 20 to 30 others that might contribute to autism to a lesser degree.

Schellenberg points out: "If an individual only gets three high-risk variants of these genes, it could mean a less-severe form of autism. And because autism is rarer in females, it may take more risk genes for a female to have autism. There also is the possibility that there might be a biological difference in autism for females versus males.”

A meaningful piece of information is the fact that the researchers have found evidence for two genetic subtypes of autism, male versus female and early versus late onset: "With Alzheimer's disease research, one big breakthrough was segregating the late and early onset forms of the disease, and this led to important genetic discoveries," added Geraldine Dawson, a professor of psychology.

The researchers are looking for autism susceptibility genes, ones that heighten the risk of an individual getting autism, just as there are genes that raise the chances of getting breast cancer.

"Once we discover these susceptibility genes, we can immediately screen infants to identify those at risk early in life. Early identification can lead to early intervention, which could have a much more dramatic effect”, said Dawson.; Source: University of Washington