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Disease characteristics

Excerpted from the GeneReview: Townes-Brocks Syndrome
Townes-Brocks syndrome (TBS) is characterized by the triad of imperforate anus (82%), dysplastic ears (88%) (overfolded superior helices and preauricular tags) frequently associated with sensorineural and/or conductive hearing impairment (65%), and thumb malformations (89%) (triphalangeal thumbs, duplication of the thumb (preaxial polydactyly), and rarely hypoplasia of the thumbs). Renal impairment (27%), including end-stage renal disease (ESRD) (42%), may occur with or without structural abnormalities (mild malrotation, ectopia, horseshoe kidney, renal hypoplasia, polycystic kidneys, vesicoutereral reflux). Congenital heart disease occurs in 25%. Foot malformations (52%) (flat feet, overlapping toes) and genitourinary malformations (36%) are common. Intellectual disability occurs in approximately 10% of cases. Rare features include iris coloboma, Duane anomaly, Arnold-Chiari malformation type 1, and growth retardation.

Associated genes

Clinical features

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  • Umbilical hernia
  • Renal hypoplasia
  • Ulnar deviation of finger
  • Short stature
  • Broad thumb
  • Hearing impairment
  • Vesicoureteral reflux
  • triphalangeal thumb
  • Preauricular pit
  • Intellectual disability
  • Short metatarsal
  • Arnold-Chiari malformation
  • Microcephaly
  • Duane anomaly
  • Bifid uterus
  • Abnormality of the vagina
  • Cognitive impairment
  • Ventricular septal defect
  • Macrotia
  • 3-4 finger syndactyly
  • Fifth toe clinodactyly
  • Pseudoepiphyses of second metacarpal
  • Aplasia/Hypoplasia of the 3rd toe
  • 3-4 toe syndactyly
  • 2-3 toe syndactyly
  • Microtia
  • Overfolding of the superior helices
  • Epibulbar dermoid
  • Cataract
  • Constipation
  • Strabismus
  • Hypothyroidism
  • Multicystic kidney dysplasia
  • Cryptorchidism
  • Hypospadias
  • Bifid scrotum
  • Renal insufficiency
  • Renal dysplasia
  • Rectovaginal fistula
  • Wide mouth
  • Facial asymmetry
  • Preauricular skin tag
  • Sensorineural hearing impairment
  • Visual impairment
  • Chorioretinal coloboma
  • Blepharophimosis
  • Iris coloboma
  • Abnormality of the ribs
  • Preaxial hand polydactyly
  • Synostosis involving metatarsal bones
  • Defect in the atrial septum
  • Tetralogy of Fallot
  • Abnormality of the pulmonary valve
  • Patent ductus arteriosus
  • Pes planus
  • Toe syndactyly
  • Camptodactyly (feet)
  • Split foot
  • Preaxial foot polydactyly
  • Gastroesophageal reflux
  • Anal atresia
  • Anal stenosis
  • Duodenal atresia
  • Bowel incontinence
  • Clinodactyly of the 5th finger
  • Ectopic anus
  • Rectoperineal fistula
  • Cranial nerve paralysis
  • Aplasia/Hypoplasia of the corpus callosum
  • Aplasia/Hypoplasia affecting the eye
  • External ear malformation
  • Hypoplasia of penis
  • Abnormality of the tragus
  • Partial duplication of the phalanges of the thumb
  • Urethral valve
  • 2-4 finger syndactyly
  • Stahl ear
  • Abnormal localization of kidney
  • Lower limb asymmetry
  • Urogenital fistula
  • Displacement of the external urethral meatus
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