Question: What is (are) Townes-Brocks syndrome ?
Answer: Townes-Brocks syndrome is a genetic condition characterized by an obstruction of the anal opening (imperforate anus), abnormally shaped ears, and hand malformations that most often affect the thumbs. Most affected individuals have at least two of these three main features. The condition is caused by mutations in the SALL1 gene which provides instructions for making proteins that are involved in the formation of tissues and organs before birth. It follows an autosomal dominant pattern of inheritance.
Source: GARD

Question: What are the symptoms of Townes-Brocks syndrome ?
Answer: What are the signs and symptoms of Townes-Brocks syndrome? Townes-Brocks syndrome is characterized by an obstruction of the anal opening (imperforate anus), abnormally shaped ears, and hand malformations that most often affect the thumbs. Most people with this condition have at least two of these three major features. Other possible signs and symptoms include kidney abnormalities, mild to profound sensorineural and/or conductive hearing loss, heart defects, and genital malformations. These features vary among affected individuals - even among those within the same family. Intellectual disability or learning problems have also been reported in about 10 percent of people with Townes-Brocks syndrome. Visit GeneReviews for more detailed information about the signs and symptoms of Townes-Brocks syndrome. The Human Phenotype Ontology provides the following list of signs and symptoms for Townes-Brocks syndrome. If the information is available, the table below includes how often the symptom is seen in people with this condition. You can use the MedlinePlus Medical Dictionary to look up the definitions for these medical terms. Signs and Symptoms Approximate number of patients (when available) External ear malformation 90% Preauricular skin tag 90% Preaxial hand polydactyly 90% Triphalangeal thumb 90% Urogenital fistula 90% Camptodactyly of toe 50% Clinodactyly of the 5th finger 50% Clinodactyly of the 5th toe 50% Constipation 50% Cryptorchidism 50% Ectopic anus 50% Hearing impairment 50% Microtia 50% Pes planus 50% Preauricular pit 50% Renal insufficiency 50% Sensorineural hearing impairment 50% Anal atresia 47% 2-4 finger syndactyly 7.5% Abnormal localization of kidney 7.5% Abnormality of the pulmonary valve 7.5% Abnormality of the ribs 7.5% Abnormality of the tragus 7.5% Abnormality of the vagina 7.5% Aplasia/Hypoplasia affecting the eye 7.5% Aplasia/Hypoplasia of the corpus callosum 7.5% Arnold-Chiari malformation 7.5% Atria septal defect 7.5% Bifid scrotum 7.5% Blepharophimosis 7.5% Bowel incontinence 7.5% Cataract 7.5% Chorioretinal coloboma 7.5% Cognitive impairment 7.5% Cranial nerve paralysis 7.5% Displacement of the external urethral meatus 7.5% Epibulbar dermoid 7.5% Facial asymmetry 7.5% Hypoplasia of penis 7.5% Hypothyroidism 7.5% Iris coloboma 7.5% Lower limb asymmetry 7.5% Multicystic kidney dysplasia 7.5% Patent ductus arteriosus 7.5% Preaxial foot polydactyly 7.5% Renal dysplasia 7.5% Renal hypoplasia 7.5% Short stature 7.5% Split foot 7.5% Strabismus 7.5% Tetralogy of Fallot 7.5% Toe syndactyly 7.5% Ulnar deviation of finger 7.5% Vesicoureteral reflux 7.5% Visual impairment 7.5% Wide mouth 7.5% Duane anomaly 5% 2-3 toe syndactyly - 3-4 finger syndactyly - 3-4 toe syndactyly - Anal stenosis - Aplasia/Hypoplasia of the 3rd toe - Autosomal dominant inheritance - Bifid uterus - Broad thumb - Duodenal atresia - Gastroesophageal reflux - Hypospadias - Intellectual disability - Macrotia - Metatarsal synostosis - Microcephaly - Overfolding of the superior helices - Partial duplication of thumb phalanx - Pseudoepiphyses of second metacarpal - Rectoperineal fistula - Rectovaginal fistula - Short metatarsal - Stahl ear - Umbilical hernia - Urethral valve - Ventricular septal defect - The Human Phenotype Ontology (HPO) has collected information on how often a sign or symptom occurs in a condition. Much of this information comes from Orphanet, a European rare disease database. The frequency of a sign or symptom is usually listed as a rough estimate of the percentage of patients who have that feature. The frequency may also be listed as a fraction. The first number of the fraction is how many people had the symptom, and the second number is the total number of people who were examined in one study. For example, a frequency of 25/25 means that in a study of 25 people all patients were found to have that symptom. Because these frequencies are based on a specific study, the fractions may be different if another group of patients are examined. Sometimes, no information on frequency is available. In these cases, the sign or symptom may be rare or common.
Source: GARD

Question: What causes Townes-Brocks syndrome ?
Answer: What causes Townes-Brocks syndrome? Townes-Brocks syndrome is caused by mutations in the SALL1 gene. This 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 symptoms associated with Townes-Brocks syndrome.
Source: GARD

Question: How to diagnose Townes-Brocks syndrome ?
Answer: How is Townes-Brocks syndrome diagnosed? Townes-Brocks syndrome is diagnosed clinically based on the presence of the following: Imperforate anus Abnormally shaped ears Typical thumb malformations (preaxial polydactyly, triphalangeal thumbs which have three bones in them, much like the fingers, instead of the normal two, hypoplastic or underdeveloped thumbs) without shortening of the radius (the larger of the two bones in the forearm) SALL1 is the only gene known to be associated with Townes-Brocks syndrome. Detection of a SALL1 mutation confirms the diagnosis. Genetic testing is available on a clinical basis.
Source: GARD