The year 2011 was a big one for autism research, with major findings that non-genetic factors play a larger role in who develops the disorder than many scientists had previously suspected.

A University of Pennsylvania study that found very low-birth-weight babies were five times as likely to later be diagnosed with an autism spectrum spectrum disorder was named one of Time magazine’s “Top 10 New Findings in Parenting.”

Other significant autism findings last year include calculations -- based on a University of Southern California study of identical and fraternal twins that was published online in Archives of General Psychiatry in July -- that shared genes accounted for just 38 percent of the risk while what scientists refer to  as environmental factors – basically everything else – were responsible for 58 percent.

And a team at the University of California, Davis, Mind Institute, reported  in the journal Pediatrics in August that younger siblings of  autistic children had a one-in-five chance of becoming autistic. (The overall risk for all children born in the United States is estimated to be about one in 110.)

The link to very low birth weight was found by Penn researchers who followed 1,105 premature babies born in three central New Jersey counties for more than two decades. It was led by Jennifer Pinto-Martin,  director of the Center for Autism and Developmental Disabilities Research and Epidemiology in the School of Nursing, and  published Oct. 26 in Pediatrics.

The study did not determine exactly what was different  about low-birth-weight infants. It could be that the same factors that cause babies to be born preterm and small also set the developing brain on an autistic path. Another possibility is that some of the interventions that kept them alive – and are allowing greater and greater numbers of  small babies to survive as medical technology continues to improve -- somehow triggered the disorder.

The Penn center was founded in 2001. With the addition of the newer Center for Autism Research at  Children’s Hospital of Philadelphia and a proposed Autism Public Health Research Institute at Drexel University School of Public Health, the city has become a major location for study of the developmental disorder.

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