Among males or females with autism spectrum disorder (ASD), male siblings are more likely to be diagnosed with ASD than female siblings, according to results from a large observational study published in JAMA Pediatrics.
Investigators sought to analyze high-confidence, sex-specific recurrence rates of ASD among sibling pairs. The study used an administrative database to assess the incidence of ASD among 3,166,542 children (mean age, 11.2 ± 4.7 years) from 1,583.271 families enrolled in commercial health care insurance plans at a large US-managed healthcare company from January 1, 2008, through February 29, 2016. Families who were studied had 2 children who were observed for ≥12 months between 4 and 18 years of age. Of these, a total of 39,460 children from 37,507 families had received an ASD diagnosis, indicating an overall population incidence of 1.25% (95% CI, 1.23%-1.26%).
Of the 3,166,542 children who were evaluated, the prevalence of ASD was 1.96% (95% CI, 1.94%-1.98%) among boys and 0.50% (95% CI, 0.49%-0.51%) among girls. When a male child had an ASD diagnosis, ASD was diagnosed in 4.2% (95% CI, 3.8%-4.7%) of female siblings and in 12.9% (95% CI, 12.2%-13.6%) of male siblings. In contrast, when a female child had an ASD diagnosis, ASD was diagnosed in 7.6% (95% CI, 6.5%-8.9%) of female siblings and in 16.7% (95% CI, 15.2%-18.4%) of male siblings.
The findings of this study support the hypothesis that ASD clusters in families because of shared genetic or environmental factors. The findings may ultimately provide more guidance for screening and family counseling, as well as improved likelihood estimates of ASD recurrence among siblings.
Palmer N, Beam A, Agniel D, et al. Association of sex with recurrence of autism spectrum disorder among siblings [published online September 25, 2017]. JAMA Pediatr. doi:10.1001/jamapediatrics.2017.2832.