Association study between autistic-like traits and polymorphisms in the autism candidate regions RELN, CNTNAP2, SHANK3, and CDH9/10

Background: Autistic-like traits (ALTs) are continuously distributed in the general population, with the autism spectrum disorder (ASD) at the upper extreme end. A genetic overlap has been shown between ALTs and ASD, indicating that common variation in ASD candidate genes may also influence ALTs. In our study, we have investigated the SNP rs4307059 that has been associated with both ALTs and ASD. In addition, we genotyped polymorphisms in a selection of genes involved in synaptic functioning, that is, SHANK3, RELN, and CNTNAP2, which repeatedly have been associated with ASD. The possible associations of these polymorphisms with ALTs, as well as genetic factors for neurodevelopmental problems (NDPs), were investigated in a large cohort from the general population: The Child and Adolescent Twin Study in Sweden. For analyses of ALTs and NDPs, 12,319 subjects (including 2,268 monozygotic (MZ) and 3,805 dizygotic (DZ) twin pairs) and 8,671 subjects (including 2,243 MZ and 2,044 DZ twin pairs), respectively, were included in the analyses. Findings: We could not replicate the previous association between rs4307059 and social communication impairment. Moreover, common variations in CNTNAP2 (rs7794745 and rs2710102), RELN (rs362691), and SHANK3 (rs9616915) were not significantly associated with ALTs in our study. Conclusions: Our results do not suggest that the investigated genes, which previously has been found associated with ASD diagnosis, have any major influence on ALTs in children from the general population.