"The Collaborative Linkage Study of Autism reported peak findings on regions of interest on 7q and 13q that were nearly entirely attributable to the subgroup of families in which both children and parents showed histories of language delay. Subsequent studies incorporating language information have provided further support for a language-related peak on chromosome 7q [Alarcon et al., 2002, 2005]."
Defining key features of the broad autism phenotype, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2746421/