Townes Brocks Syndrome

Townes Brocks Syndrome

National Organization for Rare Disorders, Inc.

Important

It is possible that the main title of the report Townes Brocks Syndrome is not the name you expected. Please check the synonyms listing to find the alternate name(s) and disorder subdivision(s) covered by this report.

Synonyms

  • Imperforate Anus with Hand, Foot and Ear Anomalies
  • Deafness, Sensorineural, with Imperforate Anus and Hypoplastic Thumbs
  • Townes Syndrome

Disorder Subdivisions

  • None

General Discussion

Townes-Brocks syndrome (TBS) is an autosomal dominant genetic disorder characterized by absence of the anal opening (imperforate anus), abnormal ears associated with hearing impairment and thumb malformations. Abnormalities in the feet, heart and kidneys also occur frequently. Townes-Brocks syndrome is associated with a mutation in the SALL1 gene.

Symptoms

The absence of the anal opening (imperforate anus) is the most common feature of TBS. Small ears and a folded rim of skin and cartilage around the outer ear are usually present. Congenital sensorineural and/or conductive hearing loss can range from mild to severe and can be progressive. The most common thumb malformations are three bones instead of two (triphalangeal thumbs) and duplicated thumbs (preaxial polydactyly). Feet anomalies occur less frequently and include a short third toe, overlapping toes and flat feet. Kidney dysfunction can occur with or without kidney malformations. Typical kidney anomalies include displaced or rotated kidneys, horseshoe kidney, polycystic kidneys, and underdeveloped kidneys. Abnormalities of the heart, eye and spine are infrequently associated with Townes-Brocks syndrome. Mental retardation occurs in approximately 10% of affected individuals.

Causes

Townes-Brocks syndrome is an autosomal dominant genetic disorder. Dominant genetic disorders occur when only a single copy of an abnormal gene is necessary for the appearance of the disease. The SALL1 gene is the only gene known to be associated with Townes-Brocks syndrome. The abnormal gene can be inherited from either parent, or can be the result of a new mutation (gene change) in the affected individual. Approximately 50% of affected individuals have the condition as a result of a new mutation. The risk of passing the abnormal gene from affected parent to offspring is 50% for each pregnancy regardless of the sex of the resulting child.

Affected Populations

The prevalence of Townes-Brock syndrome is not known but has been estimated to be at least 1 in 250,000 births. This condition affects males and females in equal numbers.

Standard Therapies

Diagnosis

The diagnosis of Townes-Brocks syndrome is based on clinical symptoms. Molecular genetic testing for mutations in the SALL1 gene is available to confirm the diagnosis.



Treatment

Treatment of Townes-Brocks syndrome often requires surgery for malformations associated with this condition. Hearing evaluation should be conducted if TBS is suspected. Ultrasound and laboratory tests should be performed to monitor kidney function. A baseline echocardiogram should be performed by a cardiologist.



Genetic counseling is recommended for affected individuals and their families.

Investigational Therapies

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.



For information about clinical trials being conducted at the National Institutes of Health (NIH) in Bethesda, MD, contact the NIH Patient Recruitment Office:



Tollfree: (800) 411-1222

TTY: (866) 411-1010

Email: prpl@cc.nih.gov



For information about clinical trials sponsored by private sources, contact:

www.centerwatch.com

References

TEXTBOOKS

Kohlhase, J. (Posted 1/24/07). Townes-Brocks Syndrome. In Genereviews at Genetests: Medical Genetics Information Resource (database online). Copyright, University of Washington, Seattle. 1997-2007. Available at http://www.genetests.org accessed 3/07.



Lachiewicz AM, Hodge C. Townes-Brocks Syndrome. In: The NORD Guide to Rare Disorders, Philadelphia: Lippincott, Williams and Wilkins, 2003:262.



JOURNAL ARTICLES

Botzenhart EM, Bartalini G, Blair E, et al. Townes-Brocks syndrome: twenty novel SALL1 mutations in sporadic and familial cases and refinement of the SALL1 hot spot region. Hum Mutat 2007:28:204-5.



Botzenhart EM, Green A, Ilyina H, et al. SALL1 mutation analysis in Townes-Brocks syndrome: twelve novel mutations and expansion of the phenotype. Hum Mutat 2005:26-282.



Devriendt K, Fryns JP, Lemmens F, et al. Somatic mosaicism and variable expression of Townes-Brocks syndrome. Am J Med Genet 2002: 111-230-1.



Kohlhase J. SALL1 mutations in Townes-Brocks syndrome and related disorders. Hum Mutat 2000: 16:460-6.



Townes PL and Brocks ER. Hereditary syndrome of imperforate anus with hand, foot and ear anomalies. J Pediatr 1972:81;321-326.

Resources

Alexander Graham Bell Association for the Deaf and Hard of Hearing

3417 Volta Place NW

Washington, DC 20007-2778

United States

Tel: (202)337-5220

Fax: (202)337-8314

Tel: (866)337-5220

TDD: (202)337-5221

Email: info@agbell.org

Internet: http://www.agbell.org



American Society for Deaf Children

800 Florida Avenue NE

2047

Washington, DC 20002-3695

Tel: (866)895-4206

Fax: (410)795-0965

Tel: (800)942-2732

Email: asdc@deafchildren.org

Internet: http://www.deafchildren.org



National Association of the Deaf

8630 Fenton Street

Suite 820

Silver Springs, MD 20910

USA

Tel: (301)587-1788

Fax: (301)587-1791

TDD: (301)587-1789

Email: NADinfo@nad.org

Internet: http://www.nad.org



NIH/National Eye Institute

31 Center Dr

MSC 2510

Bethesda, MD 20892-2510

United States

Tel: (301)496-5248

Fax: (301)402-1065

Email: 2020@nei.nih.gov

Internet: http://www.nei.nih.gov/



Kids With Heart ~ National Association for Children's Heart Disorders, Inc.

1578 Careful Dr.

Green Bay, WI 54304

Tel: (920)498-0058

Fax: (920)498-0058

Tel: (800)538-5390

Email: michelle@kidswithheart.org

Internet: http://www.kidswithheart.org



Little Hearts, Inc.

P.O. Box 171

110 Court Street, Suite 3A

Cromwell, CT 06416

USA

Tel: (860)635-0006

Fax: (860)635-0006

Tel: (866)435-4673

Email: info@littlehearts.org

Internet: http://www.littlehearts.org



Congenital Heart Information Network (C.H.I.N.)

P.O. Box 3397

Margate City, NJ 08402-0397

Tel: (609)823-4507

Fax: (609)822-1574

Email: mb@tchin.org

Internet: http://www.tchin.org



Genetic and Rare Diseases (GARD) Information Center

PO Box 8126

Gaithersburg, MD 20898-8126

Tel: (301)251-4925

Fax: (301)251-4911

Tel: (888)205-2311

TDD: (888)205-3223

Internet: http://rarediseases.info.nih.gov/GARD/



Madisons Foundation

PO Box 241956

Los Angeles, CA 90024

Tel: (310)264-0826

Fax: (310)264-4766

Email: getinfo@madisonsfoundation.org

Internet: http://www.madisonsfoundation.org



Let Them Hear Foundation

1900 University Avenue, Suite 101

East Palo Alto, CA 94303

Tel: (650)462-3174

Fax: (650)462-3144

Email: info@letthemhear.org

Internet: http://www.letthemhear.org



American Academy of Audiology

11730 Plaza America Drive, Suite 300

Reston, VA 20190

Tel: (703)790-8466

Fax: (703)790-8631

Tel: (800)222-2336

Email: infoaud@audiology.org

Internet: http://www.audiology.org



Townes-Brocks Syndrome International Support Network

Internet: http://health.groups.yahoo.com/group/Townes-Brocks-Syndrome/



Hearing Loss Association of America

7910 Woodmont Avenue

Suite 1200

Bethesda, MD 20814

Tel: (301)657-2248

Fax: (301)913-9413

Email: info@hearingloss.org

Internet: http://www.hearingloss.org



For a Complete Report

This is an abstract of a report from the National Organization for Rare Disorders, Inc.® (NORD). Cigna members can access the complete report by logging into myCigna.com. For non-Cigna members, a copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see http://www.rarediseases.org/search/rdblist.html.

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