Heritability for autism spectrum disorder varies for males and females, finds study

Heritability for autism spectrum disorder (ASD) varies for males and females, with higher heritability seen for males than females, according to a study published online April 17 in JAMA Psychiatry.

Sven Sandin, Ph.D., from the Karolinska Institutet in Stockholm, and colleagues estimated the sex-specific heritability of ASD in a population-based, retrospective analysis of nontwin siblings and cousins from Sweden born between Jan. 1, 1985, and Dec. 31, 1998, with follow-up to age 19 years. The relative variance in risk for ASD occurrence due to sex-specific additive genetics, shared environmental effects, and a common residual term, which conceptually captured other factors that promote individual behavioral variation, was estimated.

The sample included 1,047,649 individuals in 456,832 families. The researchers found that 1.17% of the entire sample received a diagnosis of ASD, including 1.51% of males and 0.80% of females. For males and females, ASD heritability was estimated at 87.0 and 75.7%, respectively, with the difference in heritability estimated at 11.3%. No support was seen for shared environmental contributions.

"The skewed sex ratio in ASD may, partly, be explained by differences in genetic variance between sexes," the authors write. "This discovery opens up new avenues for further research aimed at gaining a deeper understanding of the prevalence of ASD."

A related editorial in JAMA Psychiatry appears here.

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