A systematic assessment of clinical history and cognitive deficits across multiple XLID-associated genes led to the observation that ZDHHC9 mutations are associated with homogeneous neurological and cognitive features, including disproportionate attention problems, language impairment, and deficits in oromotor control in the context of mild to moderate intellectual disability (Baker et al. 2015). This evidence concerns the gene ZDHHC9 and cask-related x-linked intellectual disability.