Autism Risk 3 to 5% for Children Whose Aunts or Uncles Have Autism, New Study Finds
Approximately 3 to 5% of children who have an aunt or uncle with autism spectrum disorder (ASD) are likely to have autism themselves, according to a new study funded by the National Institutes of Health. The study, published in the journal Biological Psychiatry and conducted by Dr. John Constantino at Washington University in St. Louis, also found that a child whose mother has a sibling with autism is not more likely to be affected by autism than a child whose father has a sibling on the autism spectrum.
According to NIH.gov, the study’s results were based on the records of almost 850,000 Swedish children born between 2003 and 2012 and their families. 13,000 of the children were diagnosed with autism. Children of mothers with one or more siblings with autism were found to be three times more likely to have autism than children in the general population. Children of fathers with a sibling or siblings with autism were found to be twice as likely to have autism as children in the general population.
Dr. Alice Kau, of the Intellectual and Developmental Disabilities Branch of NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), said the results of the study “offer important new information for counseling people who have a sibling with ASD.” She added that the study’s findings suggest that the higher prevalence of autism in males is not due to the so-called “female protective effect,” a theory that females have a lower rate of autism than males because they have a greater tolerance of autism risk factors. Previous studies have found that three times more males have autism than females, though the exact reasons for this remain unknown.
Constantino agreed that the study’s findings challenge the “female protective effect,” because if the effect existed, children of mothers whose siblings have autism would have up to a 30% higher risk of autism. The researchers also found no statistically significant increase in autism risk for children whose uncle’s have autism, compared with children whose aunts are on the autism spectrum.