The broader language phenotype of autism: a comparison with specific language impairment

Abstract
Background: Some individuals with autism spectrum disorders (ASD) experience linguistic difficulties similar to those found in individuals with specific language impairment (SLI). Whether these behaviours are indicative of a common underlying genetic cause or a superficial similarity is unclear. Methods: Standardised language assessments were administered to three participant groups: parents of children with ASD (Par‐A), parents of children with specific language/literacy impairment (Par‐L) and parents of typically developing children (Par‐T) (n = 30, in each group). Additionally, the Autism‐Spectrum Quotient (AQ) was used to assess autism‐like tendencies, in particular, social language use. Results: The Par‐A group performed better than the Par‐L group (and identical to the Par‐T group) on all language tests. Conversely, the Par‐A group was characterised by higher levels of pragmatic difficulties than the other two groups, as measured by the communication subscale of the AQ. Conclusions: No evidence was found for a shared phenotype in parents of children with ASD and SLI. A model is presented describing the relation between SLI and ASD.