A new study show siblings of children diagnosed with autism spectrum disorder are at a higher risk of developing ASD.
"A Danish study of siblings suggests the recurrence risks for autism spectrum disorders (ASDs) varied from 4.5 percent to 10.5 percent depending on the birth years, which is higher than the ASD risk of 1.18 percent in the overall Danish population," according to a news release.
JAMA Pediatrics, a JAMA Network publication, published the study from the Aarhus University, Denmark, according to a news release:
Therese K. Grønborg, M.Sc., of Aarhus University, Denmark, and colleagues conducted a population-based study in Denmark of all children (about 1.5 million) born between 1980 and 2004. They identified a maternal sibling group derived from mothers with at least two children and a paternal sibling group derived from fathers with at least two children...
The study results suggest an almost seven-fold increase in ASDs risk if an older sibling had an ASD diagnosis compared with no ASD diagnoses in older siblings. In children with the same mother, the adjusted relative recurrence risk of 7.5 in full siblings was significantly higher than the risk of 2.4 in half siblings. In children with the same father, the adjusted relative recurrence risk was 7.4 in full siblings and significant, but no statistically significant increased risk was observed among paternal half siblings, the results also indicate.
"I think a lot of autism researchers agree that the causes of autism are many and it's very complex," Gronborg, who led the study at Aarhus University, told Reuters. "If it was only genetics we would see a much higher recurrence rate [among siblings]."
According to Reuters, about one in 88 U.S. children have ASD, citing a report form the Centers for Disease Control and Prevention.
The results from the study suggest there is almost a seven-fold increase in ASDs risk if an older sibling had an ASD diagnosis.
"The difference in the recurrence risk between full and half siblings supports the role of genetics in ASDs, while the significant recurrence risk in maternal half-siblings may support the role of factors associated with pregnancy and the maternal intrauterine environment in ASDs," the study concludes.
