Fragile XE syndrome

Title

Other Names:

FRAXE syndrome; Fragile site, folic acid type; X-linked mental retardation associated with fragile site FRAXE

Categories:

Congenital and Genetic Diseases; Nervous System Diseases

Summary Summary

Fragile XE syndrome (FRAXE) is a genetic condition associated with mild to borderline intellectual disabilities with physical features differing from person to person. The characteristic features are learning difficulties, often a consequence of communication problems (speech delay, poor writing skills), hyperactivity, and a shortened attention span. Nearly all cases of FRAXE are caused by a specific type of mutation, called a trinucleotide repeat expansion, in the AFF2 gene, which is located on the X chromosome. A trinucleotide repeat expansion occurs when there is an abnormally large number of repeats of a specific sequence of three nucleotides (building block of DNA) within our DNA. The repeating nucleotides in FRAXE syndrome are CCG. When the number of CCG repeats is over 200, people typically have the signs and symptoms seen in FRAXE. FRAXE is inherited in an X-linked manner.^[1]^[2]^[3] Although there is no specific treatment for FRAXE, there may be ways to manage the symptoms. A team of doctors or specialists is often needed to figure out the treatment options for each person.

Last updated: 9/9/2016

Symptoms Symptoms

The Human Phenotype Ontology (HPO) provides the following list of features that have been reported in people with this condition. Much of the information in the HPO comes from Orphanet, a European rare disease database. If available, the list includes a rough estimate of how common a feature is (its frequency). Frequencies are based on a specific study and may not be representative of all studies. You can use the MedlinePlus Medical Dictionary for definitions of the terms below.

Signs and Symptoms	Approximate number of patients (when available)
Abnormality of metabolism/homeostasis	-
Aggressive behavior	-
Agitation	-
Delayed speech and language development	-
Epicanthus	-
Hyperactivity	-
Impulsivity	-
Intellectual disability	-
Obsessive-compulsive behavior	-
Prominent nasal bridge	-
X-linked recessive inheritance	-

Last updated: 9/1/2016

Cause Cause

FRAXE is a genetic disorder caused by mutations in the AFF2 gene. This gene provides instructions for making a protein whose function is not well understood. Nearly all cases of FRAXE are caused by a specific type of mutation, called a trinucleotide repeat. A trinucleotide repeat is an abnormal expansion of three repeats of our DNA building blocks (nucleotides). The repeating nucleotides in FRAXE are CCG. Normally, the involved segment of three nucleotides is repeated approximately 4 to 40 times. However, in people with FRAXE, the CCG segment is repeated more than 200 times, which makes this region of the gene unstable or fragile. As a result, the AFF2 gene is turned off (silenced), and no AFF2 protein is produced. It is unclear how a shortage of this protein leads to intellectual disability in people with FRAXE. Some people with FRAXE have a deletion of genetic material in the AFF2 gene.^[4]^[2]^[3]

People with 50 to 200 CCG repeats are said to have an AFF2 gene premutation. Current research suggests that people with a premutation do not have associated cognitive problems.^[2]

Last updated: 9/9/2016

Diagnosis Diagnosis

The diagnosis of FRAXE is made based on signs and symptoms and genetic testing to confirm either a trinucleotide repeat expansion or a deletion within the AFF2 gene.^[3]

Last updated: 9/9/2016

Testing Resources

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.

Research Research

Research helps us better understand diseases and can lead to advances in diagnosis and treatment. This section provides resources to help you learn about medical research and ways to get involved.

Clinical Research Resources

The National Fragile X Foundation provides a state by state list of clinical trials involving fragile X-associated disorders. Click on National Fragile X Foundation to view the list.

Organizations Organizations

Nonprofit support and advocacy groups bring together patients, families, medical professionals, and researchers. These groups often raise awareness, provide support, and develop patient-centered information. Many are the driving force behind research for better treatments and possible cures. They can direct people to research, resources, and services. Many groups also have experts who serve as medical advisors. Visit their website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD. Suggest an organization to add.

Organizations Supporting this Disease

Developmental Delay Resources (DDR)
5801 Beacon Street
Pittsburgh, PA 15217
Toll-free: 800-497-0944
Fax: 412-422-1374
E-mail: devdelay@mindspring.com
Website: http://www.devdelay.org

Organizations Providing General Support

American Association on Intellectual and Developmental Disabilities
444 North Capitol Street, NW
Suite 846
Washington, DC 20001-1512
Toll-free: (800) 424-3688
Telephone: (202) 387-1968
Fax: (202) 387-2193
Website: http://www.aaidd.org
The Society for Developmental and Behavioral Pediatrics
6728 Old McLean Village Drive
McLean, VA 22101
Telephone: 703-556-9222
E-mail: info@sdbp.org
Website: http://www.sdbp.org/index.cfm

Living With Living With

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Genetics Resources

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by GeneTests, the American College of Medical Genetics, and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from Genetics Home Reference.

Learn More Learn More

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.

Where to Start

The National Center on Birth Defects and Developmental Disabilities (NCBDDD) at the Center for Disease Control and Prevention (CDC) provides information about developmental disabilities, including intellectual disability. To view this information, click on the link below.
Link: http://www.cdc.gov/ncbddd/dd/ddmr.htm
Genetics Home Reference (GHR) contains information on Fragile XE syndrome. This website is maintained by the National Library of Medicine.

In-Depth Information

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 XE syndrome. Click on the link to view a sample search on this topic.

GARD Answers GARD Answers

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References References

Gecz J. The FMR2 gene, FRAXE and non-specific X-linked mental retardation: clinical and molecular aspects. Ann. Hum. Genet. Mar 2000; 64(Pt 2):95-106. http://www.ncbi.nlm.nih.gov/pubmed/?term=11246464.
fragile XE syndrome. Genetics Home Reference. January 2014; https://ghr.nlm.nih.gov/condition/fragile-xe-syndrome.
Victor A. McKusick. MENTAL RETARDATION, X-LINKED, ASSOCIATED WITH FRAGILE SITE FRAXE. In: Cassandra L. Kniffin. OMIM. 9/22/2011; http://omim.org/entry/309548.
Rimoin DL, Connor JM, Pyeritz RE, Korf BR. Emery and Rimoin's Principles and Practice of Medical Genetics, 5th ed. Philadelphia: Churchill Livingstone Elsevier; 2007;