Syndromes of the first and second pharyngeal arches: A review

Our aim in this review is to discuss currently known mechanisms associated with three important syndromes of the first and second pharyngeal arches: Treacher Collins syndrome (TCS), Oculo‐auriculo‐vertebral syndrome (AOVS) and Auriculo‐Condylar syndrome (ACS) or question mark ear syndrome. TCS and A...

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Bibliographic Details
Published in:American journal of medical genetics. Part A 2009-08, Vol.149A (8), p.1853-1859
Main Authors: Passos-Bueno, Maria Rita, Ornelas, Camila C., Fanganiello, Roberto D.
Format: Article
Language:English
Subjects:
Abnormalities, Multiple - pathology
Abnormalities, Multiple - therapy
Animals
Auriculo-Condylar syndrome
Biological and medical sciences
Branchial Region - abnormalities
Branchial Region - pathology
cranial neural crest
Diseases of the osteoarticular system
epigenetic
genetic heterogeneity
Humans
Malformations and congenital and or hereditary diseases involving bones. Joint deformations
Medical genetics
Medical sciences
oculo-auriculo-vertebral syndrome
Syndrome
TCOF1
Treacher Collins syndrome
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Summary:Our aim in this review is to discuss currently known mechanisms associated with three important syndromes of the first and second pharyngeal arches: Treacher Collins syndrome (TCS), Oculo‐auriculo‐vertebral syndrome (AOVS) and Auriculo‐Condylar syndrome (ACS) or question mark ear syndrome. TCS and ACS are autosomal dominant diseases, with nearly complete penetrance and wide spectrum of clinical variability. The phenotype of the latter has several overlapping features with OAVS, but OAVS may exist in both sporadic and autosomal dominant forms. Mutations in the TCOF1 gene are predicted to cause premature termination codons, leading to haploinsuficiency of the protein treacle and causing TCS. Low amount of treacle leads ultimately to a reduction in the number of cranial neural crest cells migrating to the first and second pharyngeal arches. Other than TCS, the genes associated with ACS and OAVS are still unknown. The first locus for ACS was mapped by our group to 1p21‐23 but there is genetic heretogeneity. Genetic heterogeneity is also present in OAVS. Based on the molecular analysis of balanced translocation in an OAVS patient, it has been suggested that abnormal expression of BAPX1 possibly due to epigenetic disregulation might be involved with the etiology of OAVS. Involvement of environmental events has also been linked to the causation of OAVS. Identification of factors leading to these disorders are important for a comprehensive delineation of the molecular pathways underlying the craniofacial development from the first and the second pharyngeal arches, for genetic counseling and to open alternative strategies for patient treatment. © 2009 Wiley‐Liss, Inc.
ISSN:1552-4825
1552-4833
DOI:10.1002/ajmg.a.32950