There is a phenotypic spectrum associated with mutations in the CASK gene. This includes affected males and females with mild to severe intellectual disability, with or without dysmorphic features, and unaffected carrier females.
Ocular abnormalities, specifically nystagmus and strabismus, appear to be common findings, including in some carrier females with normal intelligence. Other neurological findings such as gait abnormalities, seizures, and a resting tremor have also been described in individuals with CASK mutations.
An FG-like phenotype in one family has also been associated with mutations in this gene.