The shared environment of twins—possibly in utero as well as in childhood—ups the risk of brain incidental findings associated with autism spectrum disorder (ASD) in both siblings even when only one of them has ASD, according to an MRI-based study published online Nov. 22 in Autism Research.
Julio Monterrey, MD, MS, and colleagues at Stanford compared the MR brain scans of 50 “case pairs” of twin children in whom at least one twin had a diagnosis of ASD with the scans of 32 non-ASD control pairs.
They found that incidental findings were present in 68 percent of subjects with ASD, 71 percent of unaffected ASD siblings and 58 percent of control subjects.
Also, incidental findings requiring clinical follow-up occurred more frequently in the subjects with ASD (17 percent) compared to the controls (5 percent).
The concordance rate of incidental findings in twins was 83 percent.
Applying a mixed-effects model, the researchers found male sex and “family environment” to be significantly associated with incidental findings.
They also found a significant association with younger age, although the study abstract does not specify the age ranges of the children.
There was no difference in the prevalence of incidental findings between ASD subjects and controls; however, more incidental findings required clinical follow-up in ASD subjects compared to the controls.
Noting that the prevalence of incidental findings observed in this twin study was higher than rates previously reported in single-subject studies, Monterrey et al. suggest that brain MRI in the initial workup of ASD may be indicated in twins, especially in males.
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