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At a glance

A very rare syndrome that can also be associated with cardiac and neurological anomalies. REAR is an acronym that stands for Renal-Ear-Anal-Radial. Association of progressive renal insufficiency, external ear abnormalities and deafness, anorectal malformation, and abnormalities of the extremities (polydactyly and syndactyly).

Synonyms

Townes-Brocks Syndrome (TBS); Imperforate Anus, Hand, Foot, and Ear Anomalies; Sensorineural Deafness with Imperforate Anus and Hypoplastic Thumbs Syndrome; Branchiootorenal-like Syndrome; TBS.

History

First described by P. L. Townes, geneticist and pediatrician, and E. R. Brocks, a medical student, in 1972.

Incidence

Around 200 patients have been described, males and females equally affected.

Genetic inheritance

Autosomal dominant, total penetrance, variable expressivity. The gene (SALL1) is mapped on chromosome 16 (16q12.1).

Pathophysiology

Caused by consequence of a mutation in a gene coding for a transcription factor (SALL1). A potentially second mutation has been described in the DACT1 gene in 14q23 termed Townes-Brocks Syndrome type 2.

Diagnosis

Association of three main malformations: anorectal malformations (imperforate anus), hand and feet deformities, and external ear abnormalities. Minor features include sensorineural deafness, cardiac disease, and progressive renal failure.

Clinical aspects

Features include gastrointestinal signs (duodenal atresia, imperforate anus, anal stenosis, anterior placement of anus, rectovaginal/rectoperineal fistula), abnormality of the extremity (radial ray deformities, broad thumb, bifid thumb, triphalangeal thumb, preaxial polydactyly, syndactyly, fusion of metatarsals, absent/hypoplastic third toe, fifth toe clinodactyly, pseudoepiphysis of second metacarpal), ear deformations (overfolding of superior helix, large ears, preauricular tags, preauricular pits, microtia satyr ear, sensorineural hearing), cardiovascular anomalies (eg, tetralogy of Fallot or ventricular septal defect), microcephaly (with some cases of mental retardation), and multiple genitourinary deformations (hypospadias, bifid scrotum, prominent midline perineal raphe, hypoplastic kidneys, vesicoureteral reflux, urethral valves, multicystic kidneys, dysplastic kidneys, renal failure). Associations with ☞Goldenhar Syndrome and micro/retrognathia have been reported.

Precautions before anesthesia

Evaluate cardiac function (clinical, ECG, echocardiography, radionuclide imaging if necessary); renal function (blood analysis: kaliemia, creatinine, sodium, abdominal echography, eventually computed tomography [CT] scan).

Anesthetic considerations

Children will present for multiple surgeries. Anesthetic management will be adapted primarily to both cardiopathy and renal status. Micrognathia may present unique airway challenges that will improve with age. Venous access and pulse oximetry can be more difficult because of extremity deformities. Fluid regimen must be adapted to renal status. Prophylactic antibiotics must be done in case of cardiopathy.

Pharmacological implications

Avoid cardiac-depressive drugs; prefer drugs with hepatic or plasmatic metabolism. Aminoglycosides are not contraindicated but must be adapted to renal clearance and benefit has to be clearly evaluated in ...

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