Townes–Brocks syndrome

Townes–Brocks Syndrome

Diagram of autosomal dominant inheritance pattern.

Townes–Brocks syndrome (TBS) is a rare genetic disorder characterized by a triad of congenital anomalies: anorectal malformations, ear abnormalities, and thumb malformations. It is an autosomal dominant condition, meaning that a single copy of the altered gene in each cell is sufficient to cause the disorder.

Etiology

Townes–Brocks syndrome is caused by mutations in the SALL1 gene, which provides instructions for making a protein that is involved in the development of many parts of the body. The SALL1 protein is a transcription factor that regulates the activity of other genes, particularly during embryonic development.

Clinical Features

The clinical presentation of Townes–Brocks syndrome can vary widely among affected individuals, even within the same family. The most common features include:

• Anorectal malformations: These can range from mild anal stenosis to more severe forms such as imperforate anus.
• Ear abnormalities: These may include preauricular tags, hearing loss, and structural ear defects.
• Thumb malformations: These can include triphalangeal thumbs, duplicated thumbs, or hypoplastic thumbs.

Other possible features include renal anomalies, cardiac defects, and genitourinary abnormalities.

Diagnosis

Diagnosis of Townes–Brocks syndrome is based on clinical findings and can be confirmed by genetic testing to identify mutations in the SALL1 gene. Prenatal diagnosis is possible if the mutation in the family is known.

Management

Management of Townes–Brocks syndrome is symptomatic and supportive. It may involve surgical correction of anorectal malformations, hearing aids for hearing loss, and orthopedic interventions for limb anomalies. Regular monitoring of renal function and cardiac health is also recommended.

Related Pages

• Genetic disorder
• Autosomal dominant
• Congenital anomaly
• SALL1