Treacher Collins Syndrome
Overview
Plain-Language Overview
Treacher Collins Syndrome is a genetic condition that mainly affects the development of bones and tissues in the face. It primarily involves the craniofacial skeleton, including the cheekbones, jaw, and ears. People with this condition often have distinctive facial features such as underdeveloped cheekbones, a small jaw, and sometimes missing or malformed ears. These changes can affect hearing and breathing, as well as cause difficulties with feeding and speech. The condition varies in severity, with some individuals having mild changes and others more significant facial differences. It is present from birth and affects the head and neck region specifically.
Clinical Definition
Treacher Collins Syndrome is a congenital disorder characterized by craniofacial malformations due to abnormal development of the first and second pharyngeal arches. It is most commonly caused by mutations in the TCOF1 gene, which encodes the protein treacle, essential for neural crest cell survival and migration. The resulting deficiency in neural crest cells leads to hypoplasia of the zygomatic bones, mandible, and external ears. Clinically, it presents with malar hypoplasia, micrognathia, downward-slanting palpebral fissures, and conductive hearing loss due to middle ear anomalies. The syndrome is inherited in an autosomal dominant pattern with variable expressivity. The major clinical significance lies in the potential for airway obstruction, feeding difficulties, and hearing impairment.