1.27 EARLY QUANTITATIVE MEASURES OF AUTISM SPECTRUM DISORDER PHENOTYPES IN TODDLERS: HERITABILITY AND LONGITUDINAL STABILITY

Abstract

We previously demonstrated that a video-referenced rating of reciprocal social behavior (vrRSB), a novel toddler measure in which caregivers rate their child’s level of RSB compared with a typically developing video anchor, shows strong psychometric properties and marked impairments of RSB in toddlers with ASD. Here, we compare heritability of total RSB scores at ages 18 and 36 months; examine longitudinal stability of RSB scores from 18 to 36 months of age, when ASD frequently manifests; and estimate 18-month heritability of social visual engagement (SVE), a quantitative eye-tracking measure that has been shown to predict ASD in infancy.