Variability in the common genetic architecture of social-communication spectrum phenotypes during childhood and adolescence

Background: Social-communication abilities are heritable traits, and their impairments overlap with the autism continuum. To characterise the genetic architecture of social-communication difficulties developmentally and identify genetic links with the autistic dimension, we conducted a genome-wide screen of social-communication problems at multiple time-points during childhood and adolescence.

Methods: Social-communication difficulties were ascertained at ages 8, 11, 14 and 17 years in a UK population-based birth cohort (Avon Longitudinal Study of Parents and Children; N

Results: GCTA heritability was strongest in childhood (h(2)((8 years)) = 0.24) and especially in later adolescence (h(2) ((17 years)) = 0.45), with a marked drop during early tomiddle adolescence (h(2) ((11 years))= 0.16 and h(2)((14 years)) = 0.08). Genome-wide screens at ages 8 and 17 years identified for the latter time-point evidence for association at 3p22.2 near SCN11A (rs4453791, P = 9.3x10(-9); genome-wide empirical P = 0.011) and suggestive evidence at 20p12.3 at PLCB1 (rs3761168, P = 7.9x10(-8); genome-wide empirical P = 0.085). None of these signals contributed to risk for autism. However, the co-location of population-based signals and autism susceptibility loci harbouring rare mutations, such as PLCB1, is unlikely to be due to chance (genome-wide empirical Pco-location = 0.007).

Conclusions: Our findings suggest that measurable common genetic effects for social-communication