Autism risk higher among children whose parents have sibling with autism
Children with parents who have a sibling with autism spectrum disorder are at a higher risk for the condition compared with the general population, according to the results of a study published in Biological Psychiatry.
The study also showed that the risk for ASD was similar among children whose mothers had a sibling with ASD compared with children whose fathers had a sibling with ASD, contradicting the “female protective effect,” the authors wrote.
“Our findings do not suggest female protective factors as the principal mechanism underlying the male sex bias in ASD,” they wrote.
For the study, Sven Sandin, PhD, a statistician for the Karolinska Institute in Stockholm, Sweden, and colleagues analyzed data from a Swedish patient registry containing information on 847,732 children born between 2003 and 2012, including 13,103 (1.55%) who had an ASD diagnosis. Of those children, 8,216 were diagnosed with AD.
The median age of onset among children diagnosed with ASD was 7.72 years. Among the total cohort, 87.5% (n = 742,125) of children had a maternal aunt or uncle, while 87.6% (n = 742,813) had a paternal aunt or uncle.
Presence of ASD diagnosis in maternal aunt or uncle was associated with an increased risk for ASD (RR = 3.05; 95% CI, 2.52-3.64), as was the presence of an ASD diagnosis in a paternal sibling (RR = 2.08; 95% CI, 1.54-2.26). The prevalence of ASD among children with an aunt or uncle with ASD was approximately 3% to 5%, according to an NIH news release about the study.
After the authors adjusted the data for confounding, the rates were slightly mitigated for maternal lineage (RR = 1.88; 95% CI, 1.54-2.26) and paternal lineage (RR = 1.44; 95% CI, 1.05-1.86), the researchers reported.
The relative risks were similar for ASD in aunts and uncles for both maternal and paternal lineages, according to the study.
“The results offer important new information for counseling people who have a sibling with ASD,” Alice Kau, PhD, of the Intellectual and Developmental Disabilities Branch of NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development, said in the NIH release. “The findings also suggest that the greater prevalence of ASD in males is likely not due to a female protective effect.”