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Genetic and Rare Diseases Information Center (GARD)

Other Names for this Disease
  • Fra(X) syndrome
  • FRAXA syndrome
  • FXS
  • Marker X syndrome
  • Martin-Bell syndrome
More Names
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Fragile X syndrome is a genetic condition involving changes in part of the X chromosome.[1] This condition causes a range of developmental problems including learning disabilities and cognitive impairment.[2] It is the most common form of inherited intellectual disability in males and a significant cause of intellectual disability in females.[1]  Fragile X syndrome is caused by a change in the FMR1 gene.[1][2] Fragile X syndrome is inherited in an X-linked dominant pattern.[2]
Last updated: 6/23/2011


  1. Haldeman-Englert C. Fragile X syndrome. MedlinePlus. 2007; Accessed 4/20/2009.
  2. Fragile X syndrome. Genetics Home Reference (GHR). April 2012; Accessed 6/5/2013.
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Basic Information

  • The Centers for Disease Control and Prevention (CDC) provides information on fragile X associated disorders and research. Click on the link above to visit the CDC's Fragile X Syndrome home page.
  • Genetics Home Reference (GHR) contains information on Fragile X syndrome. This website is maintained by the National Library of Medicine.
  • MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
  • The Merck Manuals Online Medical Library provides information on this condition. Click on the link to view the information.
  • The National Human Genome Research Institute's (NHGRI) mission encompasses a broad range of studies aimed at understanding the structure and function of the human genome and its role in health and disease. Click on the link to view the information page on this topic.
  • 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

  • Medscape Reference provides information on this topic. Click on the link to view this information. You may need to register to view the medical textbook, but registration is free.
  • The Online Mendelian Inheritance in Man (OMIM) is an catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine. 
  • 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 Fragile X syndrome. Click on the link to view a sample search on this topic.