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Genetic and Rare Diseases Information Center (GARD)

Other Names for this Disease
  • FGS
  • FGS1
  • Keller syndrome
  • Mental retardation, large head, imperforate anus, congenital hypotonia, and partial agenesis of corpus callosum
  • Opitz-Kaveggia syndrome
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FG syndrome (FGS) is a genetic condition that affects many parts of the body and occurs almost exclusively in males. "FG" represents the surname initials of the first individuals diagnosed with the disorder. People with FGS frequently have intellectual disability ranging from mild to severe, hypotonia, constipation and/or anal anomalies, a distinctive facial appearance, broad thumbs and great toes, a large head compared to body size (relative macrocephaly), and abnormalities of the corpus callosum. Medical problems including heart defects, seizures, undescended testicle, and an inguinal hernia have also been reported in some affected individuals. Researchers have identified five regions of the X chromosome that are linked to FGS in affected families. The condition is called FGS1 when it is caused by a change (mutation) in a gene called MED12. FGS2 is caused by mutations in the FLNA gene. The genes responsible for FGS3, FGS4, and FGS5 remain unknown. FGS is inherited in an X-linked recessive pattern.[1]
Last updated: 1/11/2010


  1. FG syndrome. Genetics Home Reference. November 2008; Accessed 1/11/2010.
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Basic Information

  • Genetics Home Reference (GHR) contains information on FG syndrome. This website is maintained by the National Library of Medicine.
  • The National Organization for Rare Disorders (NORD) is a federation of more than 130 nonprofit voluntary health organizations serving people with rare disorders. Click on the link to view information on this topic.

In Depth Information

  • The Online Mendelian Inheritance in Man (OMIM) database contains genetics resources that discuss the different types of FG syndrome. Click on the links below to go to OMIM and review these resources.
    FG syndrome 1
    FG syndrome 2
    FG syndrome 3
    FG syndrome 4
    FG syndrome 5
  • Orphanet is a European reference portal for information on rare diseases and orphan drugs.  Access to this database is free of charge.
  • PubMed is a searchable database of medical literature and lists journal articles that discuss FG syndrome. Click on the link to view a sample search on this topic.