Bio 361 Section 001
Dr. Brenda Grubb
November 11, 2010
Treacher Collins Syndrome
Treacher Collins syndrome is an autosomal dominant disorder that affects the
development of the face and head. It consist of several malformations of the face and can
also affect the development of the middle ear resulting in deafness. It is derived from
neural crest cells which contain the gene TCOF1. Treacher Collins syndrome results
when there is a loss-of-function mutation in the TCOF1 gene which encodes Treacle.
Treacle is a nucleolar phosphoprotein that is and plays a central role in pre-ribosomal
processing and ribosomal biogenesis. There is depletion and a reduced number in neural
crest cells due to haploinsufficiency in mice. This results in high levels of cell death in
Treacher Collins syndrome, also known as manidibulofacial dysostosis, is an
autosomal dominant disorder which derived from neural crest cells and affects the
development of the head and face. Even though it is often found to be autosomal
dominant, there is a possibility that it could be autosomal recessive as well. Treacher
Collins syndrome has been found in several races such as Caucasians, African Americans,
Chinese, Japanese, and Asiatic Indians.Dixon states that Treacher Collins syndrome
affects the development of the face in about 1 in 50,000 live births and is thought to be
the result of a de novo mutation. However, there are several theories proposed to explain
the cellular basis of the tissues that are affected within the cranial neural crest.
theories that were proposed include abnormal neural crest cell migration, improper
cellular differentiation during development, or an abnormality of the extracellular matrix.
In fact, a mutated gene known as TCOF1 was identified using genetic, physical, and
transcript mapping techniques. Treacle, which is encoded by TCOF1, is defined as a low
complexity, serine/alanine-rich, nucleolar phosphoprotein.
Treacher Collins syndrome consists of major clinical features such as
abnormalities of the external ear, atresia of external auditory canals, deep eyelid furrows,
and malar hypoplasia. Hearing loss is often a result of these major clinical features. Other
features of Treacher Collins syndrome are coloboma which is a defect of the lower eye,
small jaw, large mouth, cleft palate, and the scalp reaches to the cheeks. The other
features that occur occasionally include pharyngeal hypoplasia which is the
underdevelopment of the pharynx, notches of the upper lid, bony or membranous closure
of one or both of the openings between the nasal cavity and the nasopharynx, congenital
heart defect, and absence of the parotid gland .
Research was conducted by Dixon on the molecular genetics of Treacher Collins