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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®

Townes-Brocks Syndrome

Reviewed October 2007

What is Townes-Brocks Syndrome?

Townes-Brocks syndrome is a genetic condition that affects several parts of the body. The most common features of this condition are an obstruction of the anal opening (imperforate anus), abnormally shaped ears, and hand malformations that most often affect the thumb. Most people with this condition have at least two of these three major features.

Other possible signs and symptoms of Townes-Brocks syndrome include kidney abnormalities, mild to profound hearing loss, heart defects, and genital malformations. These features vary among affected individuals, even within the same family. Intellectual disability or learning problems have also been reported in about 10 percent of people with Townes-Brocks syndrome.

How common is Townes-Brocks Syndrome?

The prevalence of this condition is unknown, although one study estimated that it may affect 1 in 250,000 people. It is difficult to determine how frequently Townes-Brocks syndrome occurs because the varied signs and symptoms of this disorder overlap with those of other genetic syndromes.

What genes are related to Townes-Brocks Syndrome?

Mutations in the SALL1 gene cause Townes-Brocks Syndrome. The SALL1 gene is part of a group of genes called the SALL family. These genes provide instructions for making proteins that are involved in the formation of tissues and organs before birth. SALL proteins act as transcription factors, which means they attach (bind) to specific regions of DNA and help control the activity of particular genes. Some mutations in the SALL1 gene lead to the production of an abnormally short version of the SALL1 protein that malfunctions within the cell. Other mutations prevent one copy of the gene in each cell from making any protein. It is unclear how these genetic changes disrupt normal development and cause the birth defects associated with Townes-Brocks syndrome.

Related Gene(s)

Changes in this gene are associated with Townes-Brocks Syndrome.

  • SALL1

How do people inherit Townes-Brocks Syndrome?

This condition is inherited in an autosomal dominant pattern, which means one copy of the altered gene in each cell is sufficient to cause the disorder.

In some cases, an affected person inherits the mutation from one affected parent. Other cases result from new mutations in the gene and occur in people with no history of the disorder in their family.

Where can I find information about diagnosis or management of Townes-Brocks Syndrome?

These resources address the diagnosis or management of Townes-Brocks Syndrome and may include treatment providers.

  • Gene Review: Townes-Brocks Syndrome (
  • Genetic Testing Registry: Townes syndrome (
  • MedlinePlus Encyclopedia: Ear Disorders (image) (
  • MedlinePlus Encyclopedia: Imperforate Anus (

You might also find information on the diagnosis or management of Townes-Brocks Syndrome in Educational resources and Patient support.

General information about the diagnosis ( and management ( of genetic conditions is available in the Handbook. Read more about genetic testing (, particularly the difference between clinical tests and research tests (

To locate a healthcare provider, see How can I find a genetics professional in my area? ( in the Handbook.

Where can I find additional information about Townes-Brocks Syndrome?

You may find the following resources about Townes-Brocks Syndrome helpful. These materials are written for the general public.

You may also be interested in these resources, which are designed for healthcare professionals and researchers.

What other names do people use for Townes-Brocks Syndrome?

  • anal-ear-renal-radial malformation syndrome
  • deafness-imperforate anus-hypoplastic thumbs syndrome
  • imperforate anus-hand and foot anomalies syndrome
  • renal-ear-anal-radial syndrome (REAR)
  • sensorineural deafness-imperforate anus-hypoplastic thumbs syndrome
  • Townes syndrome

For more information about naming genetic conditions, see the Genetics Home Reference Condition Naming Guidelines ( and How are genetic conditions and genes named? ( in the Handbook.

What if I still have specific questions about Townes-Brocks Syndrome?

Ask the Genetic and Rare Diseases Information Center (

What glossary definitions help with understanding Townes-Brocks Syndrome?

anus ; autosomal ; autosomal dominant ; cell ; disability ; DNA ; gene ; imperforate anus ; inherited ; kidney ; malformation ; mutation ; obstruction ; prevalence ; protein ; renal ; sensorineural ; syndrome ; transcription

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.


  • Botzenhart EM, Bartalini G, Blair E, Brady AF, Elmslie F, Chong KL, Christy K, Torres-Martinez W, Danesino C, Deardorff MA, Fryns JP, Marlin S, Garcia-Minaur S, Hellenbroich Y, Hay BN, Penttinen M, Shashi V, Terhal P, Van Maldergem L, Whiteford ML, Zackai E, Kohlhase J. Townes-Brocks syndrome: twenty novel SALL1 mutations in sporadic and familial cases and refinement of the SALL1 hot spot region. Hum Mutat. 2007 Feb;28(2):204-5. (
  • Botzenhart EM, Green A, Ilyina H, König R, Lowry RB, Lo IF, Shohat M, Burke L, McGaughran J, Chafai R, Pierquin G, Michaelis RC, Whiteford ML, Simola KO, Rösler B, Kohlhase J. SALL1 mutation analysis in Townes-Brocks syndrome: twelve novel mutations and expansion of the phenotype. Hum Mutat. 2005 Sep;26(3):282. (
  • Gene Review: Townes-Brocks Syndrome (
  • Keegan CE, Mulliken JB, Wu BL, Korf BR. Townes-Brocks syndrome versus expanded spectrum hemifacial microsomia: review of eight patients and further evidence of a "hot spot" for mutation in the SALL1 gene. Genet Med. 2001 Jul-Aug;3(4):310-3. Review. (
  • Kiefer SM, Ohlemiller KK, Yang J, McDill BW, Kohlhase J, Rauchman M. Expression of a truncated Sall1 transcriptional repressor is responsible for Townes-Brocks syndrome birth defects. Hum Mol Genet. 2003 Sep 1;12(17):2221-7. Epub 2003 Jul 15. (
  • Powell CM, Michaelis RC. Townes-Brocks syndrome. J Med Genet. 1999 Feb;36(2):89-93. Review. (


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? ( in the Handbook.

Reviewed: October 2007
Published: February 8, 2016