Kaiser Finds Strong Autism Link Among Siblings

Kaiser Permanente has released a new study showing that incidences of autism are much higher in newborns who have siblings with the disorder.

            According to the study, which was recently published in the Journal of Developmental & Behavioral Pediatrics, a younger sibling's chance of developing an autism spectrum disorder is 14 times greater if one of their older siblings has already been diagnosed. Autism normally occurs in about one in every 68 children, according to data from the U.S. Centers for Disease Control and Prevention.

            Researchers from Kaiser examined the healthcare system's medical records of 53,336 children born to the same mother between 28 and 42 weeks of gestation between 2001 and 2010. Of those, 592 were diagnosed with an autism spectrum disorder.

            Among those younger siblings who already had an older sibling diagnosed with autism, the rate of diagnosis was 11.3%. It was only 0.92% for younger siblings diagnosed with autism whose older sibling was unaffected. The rate among brothers was significantly higher than among sisters (15% versus 7%).

            "Our study provides additional insights into how autism affects siblings," said Darios Getahun, M.D., a study senior author with Kaiser Permanente Southern California's department of research and evaluation. "These findings also contribute to a better understanding of the influence of factors such as gender on autism risk."

            Previous research from Kaiser has concluded that children born within two years of an older sibling with the disorder or more than six years after also have an elevated risk of being diagnoses.