Fragile X syndrome
Prevalence estimates on Rare Medical Network websites are calculated based on data available from numerous sources, including US and European government statistics, the NIH, Orphanet, and published epidemiologic studies. Rare disease population data is recognized to be highly variable, and based on a wide variety of source data and methodologies, so the prevalence data on this site should be assumed to be estimated and cannot be considered to be absolutely correct.
Age of Onset
Autosomal dominant ?A pathogenic variant in only one gene copy in each cell is sufficient to cause an autosomal dominant disease
Autosomal recessive ?Pathogenic variants in both copies of each gene of the chromosome are needed to cause an autosomal recessive disease and observe the mutant phenotype
X-linked dominant ?X-linked dominant inheritance, sometimes referred to as X-linked dominance, is a mode of genetic inheritance by which a dominant gene is carried on the X chromosome.
X-linked recessive ?Pathogenic variants in both copies of a gene on the X chromosome cause an X-linked recessive disorder
Mitochondrial or multigenic ?Mitochondrial genetic disorders can be caused by changes (mutations) in either the mitochondrial DNA or nuclear DNA that lead to dysfunction of the mitochondria and inadequate production of energy.
Multigenic or multifactor ?Inheritance involving many factors, of which at least one is genetic but none is of overwhelming importance, as in the causation of a disease by multiple genetic and environmental factors.
Other Names (AKA)
Marker X syndrome; Martin-Bell syndrome; FRAXA syndrome;
Congenital and Genetic Diseases; Ear, Nose, and Throat Diseases; Endocrine Diseases;
This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.
|Medical Terms||Other Names||
|80%-99% of people have these symptoms|
|Chronic otitis media||
Chronic infections of the middle ear
|Intellectual disability, moderate||
IQ between 34 and 49
[ more ]
|Neurological speech impairment||
[ more ]
[ more ]
|30%-79% of people have these symptoms|
|Attention deficit hyperactivity disorder||
Attention deficit disorder
Attention deficit-hyperactivity disorder
Childhood attention deficit/hyperactivity disorder
[ more ]
Acid reflux disease
[ more ]
Increased size of forehead
Elongation of face
Increased height of face
Increased length of face
Vertical elongation of face
Vertical enlargement of face
Vertical overgrowth of face
[ more ]
Increased size of skull
Large head circumference
[ more ]
Big lower jaw
Increased projection of lower jaw
Increased size of lower jaw
Large lower jaw
Prominent lower jaw
[ more ]
Low or weak muscle tone
Decreased breadth of face
Decreased width of face
[ more ]
[ more ]
|5%-29% of people have these symptoms|
Excessive, persistent worry and fear
|Ascending tubular aorta aneurysm||
Bulging of wall of large artery located above heart
|Cerebral cortical atrophy||
Decrease in size of the outer layer of the brain due to loss of brain cells
|Mitral valve prolapse||0001634|
[ more ]
|Percent of people who have these symptoms is not available through HPO|
|Abnormal head movements||0002457|
|Coarse facial features||
Coarse facial appearance
More active than typical
|Poor eye contact||0000817|
People with 55 to 200 repeats of the CGG segment are said to have an FMR1 premutation. Most people with a premutation are intellectually normal. In some cases, people with a premutation have lower levels of the gene's protein and may have some mild symptoms of FXS. About 20% of women with a premutation have premature ovarian failure, and some people with a premutation have an increased risk of developing fragile X-associated tremor/ataxia syndrome (FXTAS).
The Genetic Testing Registry (GTR) provides information about the labs that offer genetic testing for fragile X syndrome. The intended audience for the GTR is health care providers and researchers. People with questions about genetic testing should speak with a health care provider or genetics professional.
- The American College of Medical Genetics (ACMG) Laboratory Quality Assurance (Lab QA) Committee has the mission of maintaining high technical standards for the performance and interpretation of genetic tests. In part, this is accomplished by the publication of the document "ACMG Standards and Guidelines for Clinical Genetics Laboratories." These standards and guidelines are designed primarily as an educational resource for clinical laboratory geneticists to help them provide quality clinical laboratory genetic services. To view the Technical Standards and Guidelines for Fragile X syndrome, visit the link above.
- The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.
- recognizing the need for special education and avoiding excessive stimulation, which may help with behavioral problems
- early educational intervention and special education that is tailored to specific learning difficulties; small class size, individual attention and avoidance of sudden change is often needed
- medications for behavioral issues that affect social interaction
- routine medical management of
strabismus, ear infections, reflux, seizures, mitral valve prolapse, and/or high blood pressure.
- American Academy of Pediatrics Guidelines: Health Supervision for Children with Fragile X Pediatrics 2011; 127: 994-1006.
- Project OrphanAnesthesia is a project whose aim is to create peer-reviewed, readily accessible guidelines for patients with rare diseases and for the anesthesiologists caring for them. The project is a collaborative effort of the German Society of Anesthesiology and Intensive Care, Orphanet, the European Society of Pediatric Anesthesia, anesthetists and rare disease experts with the aim to contribute to patient safety.
Related diseases are conditions that have similar signs and symptoms. A health care provider may consider these conditions in the table below when making a diagnosis. Please note that the table may not include all the possible conditions related to this disease.
Conditions with similar signs and symptoms from Orphanet
The differential diagnosis includes other X-linked intellectual deficiencies, Sotos syndrome, microdeletion syndromes (e.g. 22q11.2 deletion syndrome), fetal alcohol syndrome (see these terms) or idiopathic autism.
Visit the Orphanet disease page for more information.
Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.
American Association on Intellectual and Developmental Disabilities
501 3rd Street NW
Washington, DC 20001
Toll-free: (800) 424-3688
Telephone: (202) 387-1968
Fax: (202) 387-2193
The Society for Developmental and Behavioral Pediatrics
6728 Old McLean Village Drive
McLean, VA 22101
These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.
- 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.
- MedlinePlus was designed by the National Library of Medicine to help you research your health questions, and it provides more information about this topic.
- Genetics Home Reference (GHR) contains information on Fragile X syndrome. This website is maintained by the National Library of Medicine.
- The Merck Manuals Online Medical Library provides information on this condition for patients and caregivers.
- The National Human Genome Research Institute's (NHGRI) website has an information page on this topic. NHGRI is part of the National Institutes of Health and supports research on the structure and function of the human genome and its role in health and disease.
- The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.
- GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
- Medscape provides information on this topic. You may need to register to view the medical textbook, but registration is free.
- The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
- Online Mendelian Inheritance in Man (OMIM) is a 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.
- Fragile X syndrome. MedlinePlus. 2016; https://www.nlm.nih.gov/medlineplus/ency/article/001668.htm.
- Fragile X syndrome. Genetics Home Reference. April 2012; https://www.ghr.nlm.nih.gov/condition/fragile-x-syndrome.
- Saul RA & Tarleton JC. FMR1-Related Disorders. GeneReviews. April 26, 2012; https://www.ncbi.nlm.nih.gov/books/NBK1384/.
- Fragile X syndrome. Genetics Home Reference. April 2012; https://ghr.nlm.nih.gov/condition/fragile-x-syndrome.
- Carriers. The National Fragile X Foundation. https://www.fragilex.org/html/carriers.htm. Accessed 3/6/2016.
- Robert A Saul, Jack C Tarleton. FMR1-Related Disorders. GeneReviews. October 28, 2010; https://www.ncbi.nlm.nih.gov/books/NBK1384/. Accessed 6/16/2011.
- Treatments. Fragile X Research Foundation of Canada. 2009; https://www.fragilexcanada.ca/index.php?home&lng=en.