CASK and syndromic X-linked intellectual disability Najm type: MICPCH syndrome is caused by the deficiency of the X-linked gene calcium/calmodulin-dependent serine protein kinase (CASK) that encodes a membrane-associated guanylate kinase (MAGUK) family protein, containing a CaMK domain, two L27 domains, a PDZ domain, an SH3 domain, and a C-terminal guanylate kinase domain [4].