Townes-Brocks syndrome is characterized by four main signs: anal defects, ranging from simple anal anteversion to an imperforate anus with a rectovaginal fistula; malformation of the external ear (pretragial tags, malformation of the helix, stenosed external acoustic meatus); anomalies of the digits (three-phalanged thumb, bifid thumb, hexadactyly); and all types and degrees of deafness. Foot malformation, renal and cardiac diseases may also be associated. Severe anal malformations may lead to definitive postoperative encopresis in some cases. Incidence is very difficult to estimate, as the syndrome is most likely underdiagnosed. Approximately one hundred cases have been described in the literature. The condition is transmitted as an autosomal dominant trait with total penetrance and a very variable expressivity. The incriminated gene is SALL1, located on chromosome 16 (16q12.1) and coding for a transcription factor. Radial and ear defects can be corrected surgically. Deafness should be managed by a multidisciplinary team. The disorder becomes life-threatening only in cases of severe cardiac and renal malformations.
Last update: January 2005