This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Treacher Collins syndrome (TCS) is a condition that affects the development of bones and other tissues of the face. The signs and symptoms vary greatly, ranging from almost unnoticeable to severe. Most affected people have underdeveloped facial bones, particularly the cheek bones, and a very small jaw and chin (micrognathia). Other features may include cleft palate, eye abnormalities, and hearing loss. TCS may be caused by mutations in the TCOF1, POLR1C, or POLR1D genes. When the TCOF1 or POLR1D gene is responsible, it is inherited in an autosomal dominant manner. However, about 60% of autosomal dominant cases are due to a new mutation in the gene and are not inherited from a parent. When the POLR1C gene is responsible, it is inherited in an autosomal recessive manner. In some cases, the genetic cause of the condition is unknown.
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