CASK and X-linked intellectual disability: Several neurodevelopmental presentations have been reported in association with CASK variants including: X-linked intellectual disability (XLID) [2, 3], microcephaly with pontine and cerebellar hypoplasia (MICPCH) [4–6], XLID with or without nystagmus and microcephaly [7, 8], X-linked optic and ophthalmic problems [9], and FG syndrome [10, 11].