Townes-Brocks syndrome


Townes-Brocks syndrome (TBS) is a rare genetic condition present at birth. The main features include ear anomalies leading to hearing loss and characteristic anal and thumb anomalies. The range and severity of these features vary from person to person. TBS affects males and females equally. Since 1972, when the condition was first described by Dr Townes and Dr Brocks, approximately 100 individuals worldwide have been reported with the syndrome. It is difficult to estimate the true incidence of TBS because there is a possibility that TBS is currently under diagnosed. On this basis, more individuals than reported may be affected with TBS.


Medical text written September 2003 by Contact a Family. Last reviewed July 2008 by Dr M Whiteford, Consultant Clinical Geneticist, Ferguson-Smith Centre for Clinical Genetics, Glasgow, UK.

What are the symptoms?

Anal anomalies associated with TBS may include absence of a normal opening (imperforate anus) with a passage connecting the rectum to the vagina (rectovaginal fistula), abnormal placement of the anus and narrowing of the anal passage (anal stenosis). Typically, the ears of individuals with TBS may be large, or small, abnormally developed (dysplastic) ears, lop ear (over-folded ear helix) or have preauricular tags or pits (a rudimentary tag of ear tissue typically located just in front of the ear). Individuals may experience hearing loss (see entry Deafness) due to structural anomalies in the inner ear (sensorineural deafness) or because of anomalies in the external or middle ear (conductive deafness). The thumbs may be underdeveloped (hypoplastic) or have the appearance more of a finger than a thumb. Webbed fingers (syndactyly) may occur, as well as fusion of the bones in the wrist.

A number of other features may also be associated TBS. These involve other systems in the body. The bones in the feet of some children may be fused with overlapping toes leading to mobility difficulties (see entry Lower Limb Abnormalities). TBS may affect the kidney, and underdeveloped (hypoplastic) kidneys, multicystic kidneys, abnormal (dysplastic) kidneys and kidney failure have been reported (see entry Kidney disease). Abnormalities associated with the heart may include tetralogy of fallot and ventricular septal defects (see entry Heart Defects). Whilst severe heart and kidney problems may be life-threatening, many individuals with TBS have a normal life span.

Learning difficulties have been reported in some children with TBS. For others, intelligence is within the normal range.

Inheritance patterns and prenatal diagnosis

Inheritance patterns
TBS is inherited as an autosomal dominant trait. Changes in a gene located on chromosome 16 are associated with the characteristic features.

Prenatal diagnosis 
It may sometimes be possible to perform prenatal diagnosis by chorionic villus sampling (CVS) or amniocentesis during pregnancy. Genetic counselling may be helpful for individuals and families affected by this condition.

Is there support?

There is no support group for Townes-Brocks syndrome. Cross referrals to other entries in Contact’s directory are intended to provide relevant support for those particular features of the disorder. Organisations identified in those entries do not provide support specifically for Townes-Brocks syndrome.

Families can use Contact’s freephone helpline for advice, information and, where possible, links to other families. To meet other families with disabled children, join Contact’s closed (private) Facebook group.

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