Chapter category: Development
An Overview of Axenfeld-Rieger Syndrome and the Anterior Segment Developmental Disorders
The Molecular Mechanism's of Axenfeld-Rieger Syndrome
Edited by: Brad A. AmendtISBN: 0-387-26222-9
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Chapter authors:
Brad A. Amendt
The preceding chapters have described the current research on the genetic, molecular and biochemical basis for Axenfeld-Rieger syndrome (ARS). They also provided infor mation on anterior segment disorders by PITX and FOXC1 genes characterized by maldevelopment of the anterior segment of the eye. In chapter 1, Dr. Elena Semina described their initial studies that identified the human PITX2 gene on chromosome 4q25 using a positional cloning strategy. This gene was cloned from mouse at the same time by a group from the University of Michigan,1 and several other groups and has been assigned various names (Rieg, Ptx2, Otlx2, Brx1, ARP1).2-4 The three cardinal features of ARS include specific ocular anomalies of the anterior segment, dental anomalies and redundant periumbilical skin. However, other anomalies were reported in ARS patients such as pituitary, hearing, heart and limb defects that may be associated with other gene defects. Dr. Semina noted that approximately 40% of classic ARS patients have mutations in the PITX2 gene. This indicated that other genes are involved in the etiology of this disorder. Dr. Semina and Dr. Murray as well as others have identified many PITX2 mutations, which are mainly clustered in the homeodomain, however recently two missense mutations were found downstream of the homeodomain in ARS patients. 5 The phenotypic presentations of the ARS patients provided the first clues to the role of PITX2 in embryogenesis and development of the affected tissues.
Additional chapters from this book:
Role of PITX2 in the Pituitary Gland
Hoonkyo Suh, Donna M. Martin, Michael A. Charles, Igor O. Nasonkin, Philip J. Gage and Sally A. Camper
The pituitary gland is a neuroendocrine organ composed of specialized peptide hormone-producing cells that control many bodily functions. Pituitary development depends on the combined activity of ex...
An Overview of Axenfeld-Rieger Syndrome and the Anterior Segment Developmental Disorders
Brad A. Amendt
The preceding chapters have described the current research on the genetic, molecular and biochemical basis for Axenfeld-Rieger syndrome (ARS). They also provided infor mation on anterior segment dis...
The Role of PITX2 in Tooth Development
Brad A. Amendt
The transcriptional mechanisms underlying tooth development are only beginning to be understood. Axenfeld-Rieger syndrome (ARS) patients provided the first link of PITX2 to tooth development. ARS pa...
The Molecular and Biochemical Basis of Axenfeld-Rieger Syndrome
Brad A. Amendt
Mutations in the PITX2 homeobox gene are associated with Axenfeld-Rieger syn drome (ARS) and provided the first link of this transcription factor to tooth, eye, heart, and pituitary development. We ...
Rieger Syndrome and PAX6 Deletion
Ruth Riise
Rieger syndrome is a rare autosomal dominant inherited disorder mainly characterized by congenital anomalies of the anterior segment of the eye, the teeth and the skin around umbilicus.1 The anomaly...
Expression and Function of Pitx2 in Chick Heart Looping
Xueyan Yu, Shusheng Wang and YiPing Chen
Rightward looping of the straight heart tube, a vital process for the formation of multichambered heart, is the first morphological manifestation of left-right (L-R) asymme try during vertebrate emb...
The Multiple Roles of Pitx2 in Heart Development
James F. Martin
PITX2 is a paired-related homeobox gene that has been shown to be the mutated gene in Axenfeld-Rieger syndrome (ARS). The focus of this chapter will be to review recent studies that address the role...
PITX Genes and Ocular Development
Elena V. Semina
The anterior segment of the vertebrate eye is a complex arrangement of interdependent tissues of different embryonic origins. Despite its critical role in normal vision, rela tively little is curren...
Winged Helix/Forkhead Transcription Factors and Rieger Syndrome
Darryl Y. Nishimura and Ruth E. Swiderski
A second locus for Rieger syndrome (RS) was identified from chromosomal abnormali ties involving chromosome 6p25. Study of the breakpoint revealed mutations in the forkhead transcription factor (FOX...
Identification of the Gene Involved in 4q25-Linked Axenfeld-Rieger Syndrome PITX2
Elena V. Semina
Axenfeld-Rieger syndrome (ARS) is a rare autosomal dominant disorder. ARS is consid ered to be fully penetrant, but variable expressivity was reported in families. The three cardinal features of ARS...
