Watching autistic infants, who typically arch their backs and become stiff when held, may have prompted experts of the day to come up with that conclusion. Today scientists know autism is organic in nature. But the cause of 90 percent of the cases still remains a mystery. Some experts suggest neurotransmitter dysfunction in the brain, while others point to defective cell migration during brain formation, hormonal irregularities, environmental toxins, vaccines, or obstetrical complications. And there are no blood tests specific for the disorder.
Some scientists strongly believe genetics play a role.
But the research is still in the early stages. And sorting out the genetics of autism is difficult, he says, for a number of reasons. First, it may have both genetic and non-genetic causes. A person may have the mutated gene but an external trigger might be necessary for the disorder to actually occur. Another problem, he says, is that the number of people who have the mutated gene and actually get autism may be very low.