Other Names for this Disease
- Anus, imperforate, with hand, foot and ear anomalies
- Deafness, sensorineural, with imperforate anus and hypoplastic thumbs
- REAR syndrome
- Renal-ear-anal-radial syndrome
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Questions on this page
- What is Townes-Brocks syndrome?
- What are the signs and symptoms of Townes-Brocks syndrome?
- What genes are related to Townes-Brocks syndrome?
- How is Townes-Brocks syndrome diagnosed?
- Is Townes-Brocks syndrome genetic?
- Is there treatment for Townes-Brocks syndrome?
- What is the prognosis for individuals with Townes-Brocks syndrome?
In addition to these clinical features, the clinical manifestations of Townes-Brocks syndrome may include the following :
Eyes. Microphthalmia (rare), iris coloboma, lamellar cataract, chorioretinal coloboma with loss of vision
Kidneys. Renal agenesis, renal hypoplasia, polycystic kidneys; functional impairment with or without structural abnormalities (42% of cases).
Hearing. Congenital sensorineural and/or conductive hearing loss ranging from mild to severe. Hearing loss that is mild may worsen with age (65% of cases).
Heart. Congenital heart disease occurs in 50% of persons with the common p.Arg276X mutations and 12%-25% of persons with other SALL1 mutations. Defects include atrial septal defect, ventricular septal defect, tetralogy of Fallot, lethal truncus arteriosus, pulmonary valve atresia, and persistent ductus arteriosus.
Gastrointestinal. Anal stenosis, chronic constipation, gastroesophageal reflux.
Face. Hemifacial microsomia.
Lower extremities. Club foot, overlapping toes (II and IV over III), syndactyly of toes, missing toes (III) (52% of cases).
Genitourinary. Hypospadias, vaginal aplasia with bifid uterus, bifid scrotum, cryptorchidism (36% of cases).
Central nervous system.
- Mental retardation (about 10%)
- Behavioral problems, observed in many children with TBS [Kohlhase, unpublished observations]
- Arnold-Chiari malformation type I [Kohlhase, unpublished observations]
- Cranial nerve palsy (nerves VI and VII)
- Duane anomaly . Uni- or bilateral limitation of abduction of the eye associated with retraction of the globe and narrowing of the palpebral fissure on adduction. The abducens nucleus and nerve (cranial nerve VI) are absent and the lateral rectus muscle is innervated by a branch of the oculomotor nerve (cranial nerve III), accounting for the aberrant ocular movements
- Hypoplasia of the dorsal part of corpus callosum
Skeletal. Rib anomalies (fused ribs, missing ribs, additional cervical ribs), mild vertebral anomalies (9% of cases). Painful joints have been observed in several adults with TBS.
Endocrine. Congenital hypothyroidism (rare)
Growth. Postnatal growth retardation. This poorly documented feature has been described in fewer than 6% to 29% of persons reported with TBS in the literature. The occurrence of postnatal growth retardation among mutation-positive individuals is not known.
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. 
- Imperforate anus
- Dysplastic ears (overfolded superior helices, microtia)
- Typical thumb malformations (preaxial polydactyly, triphalangeal thumbs, hypoplastic thumbs) without shortening of the radius
SALL1 is the only gene known to be associated with TBS. Detection of a SALL1 mutation confirms the diagnosis. Direct sequencing of the complete SALL1 coding region and quantitative Real Time PCR analysis to identify intragenic and larger deletions are clinically available. 
- Lachiewicz AM and Hodge C. Townes-Brocks syndrome. NORD Guide to Rare Disorders. Philadelphia, PA: Lippincott Williams & Wilkins; 2003;
- Kohlhase J. Townes-Brocks Syndrome. GeneReveiws. 2007; http://www.genetests.org/query?dz=tbs. Accessed 9/5/2008.
- Townes-Brocks Syndrome. Genetics Home Reference (GHR). 2007; http://ghr.nlm.nih.gov/condition=townesbrockssyndrome. Accessed 9/5/2008.
- Marlin S. Townes-Brocks syndrome. Orphanet. 2005; http://www.orpha.net/consor/cgi-bin/OC_Exp.php?Lng=EN&Expert=857. Accessed 9/5/2008.