Researchers at the University of California in Los Angeles (UCLA) and other institutions have found two new potential genetic links with autism.
The links may indicate a predisposition to the brain disorder, according to the findings appearing in the online version of the journal Nature Genetics, which was published on Monday.
The large-scale study, which took five years, scanned the world 's largest collection of DNA samples from families affected by autism.
The findings indicate that "autism is an extremely diverse condition," said Dr. Daniel Geschwind, director of the Center for Autism Research and Treatment at UCLA.
"Our findings suggest that autism has numerous genetic origins rather than a single or a few major causes," Geschwind said.
The consortium searched for genetic commonalties in autistic individuals from about 1,200 families.
The results implicated a previously unidentified region of a chromosome, and a member of a gene family that is believed to play a key role in communication between brain cells.
One finding highlighted an area of brain cells and the genes that affect their development and function.
Because of the large number of families involved in the study, researchers were able to organize children with similar features into smaller groups, which would more easily reveal genetic links, said Rita Cantor, a professor of human genetics at the David Geffen School of Medicine at UCLA.
The five-year study of DNA samples was funded by the Autism Genome Project, an international consortium of scientists from 50 institutions in 19 countries.
The UCLA families had more than one family member diagnosed with one of three genetically related autism disorders: autism, pervasive development disorder, or Asperger's syndrome.
Autism is a complex brain disorder that appears in early childhood, disrupting the child's ability to communicate and develop social relationships.
It affects four times as many boys as girls, and the federal Centers for Disease Control and Prevention estimates that one in 150 children are diagnosed with autism spectrum disorders.