Definition

What is Townes-Brocks syndrome?

Townes-Brocks syndrome (TBS) is  is a genetic condition characterized by an absence of the anal opening (imperforate anus), abnormal ears associated with hearing impairment and thumb malformations.

How common is Townes-Brocks syndrome?

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. Please discuss with your doctor for further information.

Symptoms

What are the symptoms of Townes-Brocks syndrome?

Townes-Brocks syndrome is characterized by three main features:

  • Imperforate anus (84% of the cases)
  • Abnormally shaped ears (87% of the cases)
  • Thumb malformations (89% of the cases) such as  triphalangeal thumbs (when a thumb has 3 bones instead of 2 bones), duplication of the thumb (two tumbs), and rarely, very small thumbs).

Most people with this condition have at least two of these three major features.

Other frequent findings include:

  • Hearing problems
  • Kidney problems (such as end-stage renal disease (ESRD), which may occur with or without kidney malformations (malrotation, abnormal position (ectopia), abnormal shape (horseshoe kidney), small size (renal hypoplasia), multiple cysts in the kidney (polycystic kidneys), or vesicoutereral reflux).
  • Congenital heart disease
  • Foot malformations (flat feet, overlapping toes)
  • Genital or urinary malformations
  • Intellectual disability
  • Rare features include eye anomalies (a defect on the iris of the eye (iris coloboma), or an eye movement disorder known as Duane anomaly), Arnold-Chiari malformation type 1, and growth delay.

There may be some symptoms not listed above. If you have any concerns about a symptom, please consult your doctor.

When should I see my doctor?

If you or your loved one has any signs or symptoms listed above or you have any questions, please consult with your doctor. Everyone’s body acts differently. It is always best to discuss with your doctor what is best for your situation.

Causes

What causes Townes-Brocks syndrome?

Townes-Brocks syndrome is caused by mutations in the SALL1 gene. This 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.

Some patients with the clinical features of the syndrome have a mutation in the SALL4 gene rather than SALL1 gene. It is unclear how these genetic changes disrupt normal development and cause the  symptoms associated with Townes-Brocks syndrome.

Risk factors

What increases my risk for Townes-Brocks syndrome?

Townes-Brocks syndrome is inherited in an autosomal dominant fashion, which means that one copy of the altered gene in each cell is sufficient to cause the disorder. In about 50% of cases, an affected person inherits the mutation from an affected parent. The other 50% have the condition as a result of a new (de novo) mutation. Please consult with your doctor for further information.

Diagnosis & treatment

The information provided is not a substitute for any medical advice. ALWAYS consult with your doctor for more information.

How is Townes-Brocks syndrome diagnosed?

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.

How is Townes-Brocks syndrome treated?

Treatment is directed towards the specific symptoms, including:

  • Immediate surgical intervention for imperforate anus
  • Surgery for severe malformations of the thumbs
  • Early treatment of hearing loss

When heart defects are present, treatment is with the routine management of congenital heart defects, such as surgery and medication.

Kidney impairment is treated with hemodialysis and, in some cases, with kidney transplantation for end-stage renal disease (ESRD). Regular monitoring of kidney function in individuals, with and without kidney anomalies, is recommended.

An annual hearing testing is recommended.

Lifestyle changes & home remedies

What are some lifestyle changes or home remedies that can help me manage Townes-Brocks syndrome?

If you have any questions, please consult with your doctor to better understand the best solution for you.

Hello Health Group does not provide medical advice, diagnosis or treatment.

Sources

Review Date: February 6, 2018 | Last Modified: February 6, 2018

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