FB2026_02 , released June 18, 2026
FB2026_02 , released June 18, 2026
Human Disease Model Report: intellectual disability, X-linked, FG syndrome 4
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General Information
Name
intellectual disability, X-linked, FG syndrome 4
FlyBase ID
FBhh0000866
Disease Ontology Term
Parent Disease
OMIM
FG SYNDROME 4; FGS4
Overview

Intellectual disability, X-linked, FG syndrome 4, also called X-linked intellectual disability with or without nystagmus, is one of several diseases associated with defects in the human CASK gene; this disease exhibits X-linked recessive inheritance. Missense and hypomorphic mutations of CASK are typically implicated in this disease. See the human disease model report for 'intellectual disability, X-linked, CASK-related' (FBhh0000867) for information on experimental results using Drosophila models of this and related diseases.

[updated Aug. 2018 by FlyBase; FBrf0222196]

Disease Summary Information
Parent Disease Summary: intellectual disability, X-linked, syndromic
Symptoms and phenotype

Intellectual disability is characterized by impairments in intellectual functioning and adaptive behavior; symptoms must be present before a child becomes 18 years old (http://medical-dictionary.thefreedictionary.com/mental+retardation; 2016.01.19).

(FlyBase Curators, 2013-)

Intellectual disability can be subdivided into syndromic forms, characterized by cognitive impairment accompanied by dysmorphic features, malformations or neurological abnormalities, and nonsyndromic forms, characterized by cognitive impairment without additional features (Basel-Vanagaite, 2008; DOI: 10.1002/9780470015902.a0021454).

(FlyBase Curators, 2013-)
Specific Disease Summary: intellectual disability, X-linked, FG syndrome 4
OMIM report

[FG SYNDROME 4; FGS4](https://omim.org/entry/300422)

Human gene(s) implicated

[CALCIUM/CALMODULIN-DEPENDENT SERINE PROTEIN KINASE; CASK](https://omim.org/entry/300172)

Symptoms and phenotype

FG syndrome-4 is an X-linked recessive mental retardation syndrome characterized by congenital hypotonia, constipation, behavioral disturbances, and dysmorphic features (summary by Piluso et al., 2003). [from MIM:300422; 2018.08.14]

(OMIM, 2013-)
Genetics

FG syndrome-4 (FGS4) is caused by mutation in the CASK gene. FGS4 is typically associated with missense or hypomorphic mutations in the CASK gene. [from MIM:300422; 2018.08.14]

(OMIM, 2013-)
Cellular phenotype and pathology
Molecular information

The CASK gene encodes a calcium/calmodulin-dependent serine protein kinase that is a member of the membrane-associated guanylate kinase (MAGUK) protein family. MAGUKs are scaffolding proteins associated with intercellular junctions (summary by Atasoy et al., 2007; pubmed:17287346) [from MIM:300172; 2018.08.14]

(OMIM, 2013-)
External links
Disease synonyms
FGS4
intellectual disability, X-linked, FG sydrome 4
mental retardation, X-linked, with or without nystagmus
mental retardation with or without nystagmus
XLID with or without nystagmus
X-linked intellectual disability with or without nystagmus
Ortholog Information
Human gene(s) in FlyBase
    Human gene (HGNC)
    Symbol / Name
    CASK; calcium/calmodulin dependent serine protein kinase
    D. melanogaster ortholog (based on DIOPT)
    Comments on ortholog(s)
    Other mammalian ortholog(s) used
      D. melanogaster Gene Information (0)
      Other Genes Used: Viral, Bacterial, Synthetic (0)
        Summary of Physical Interactions (0 groups)
        Alleles Reported to Model Human Disease (Disease Ontology) (0 alleles)
        Alleles Representing Disease-Implicated Variants
        Genetic Tools, Stocks and Reagents
        Sources of Stocks
        Contact lab of origin for a reagent not available from a public stock center.
        Bloomington Stock Center Disease Page
        Related mammalian, viral, bacterial, or synthetic transgenes
        Allele
        Transgene
        Publicly Available Stocks
        Selected Drosophila transgenes
        Allele
        Transgene
        Publicly Available Stocks
        RNAi constructs available
        Allele
        Transgene
        Publicly Available Stocks
        Selected Drosophila classical alleles
        Allele
        Allele class
        Mutagen
        Publicly Available Stocks
        References (3)