ZFIN ID: ZDB-PUB-101011-26
Potential novel mechanism for Axenfeld-Rieger syndrome: deletion of a distant region containing regulatory elements of PITX2
Volkmann, B.A., Zinkevich, N.S., Mustonen, A., Schilter, K.F., Bosenko, D.V., Reis, L.M., Broeckel, U., Link, B.A., and Semina, E.
Date: 2011
Source: Investigative ophthalmology & visual science   52(3): 1450-1459 (Journal)
Registered Authors: Link, Brian, Semina, Elena
Keywords: glaucoma anterior segment, gene expression, genetic diseases
MeSH Terms:
  • Animals
  • Animals, Genetically Modified
  • Anterior Eye Segment/abnormalities
  • Anterior Eye Segment/pathology
  • Eye Abnormalities/genetics
  • Eye Abnormalities/pathology
  • Gene Deletion
  • Gene Duplication
  • Gene Expression
  • Homeodomain Proteins/genetics*
  • Humans
  • In Situ Hybridization
  • Infant
  • Male
  • Mutation
  • Plasmids
  • Regulatory Elements, Transcriptional/genetics*
  • Sequence Deletion*
  • Transcription Factors/genetics*
  • Zebrafish
PubMed: 20881290 Full text @ Invest. Ophthalmol. Vis. Sci.
Purpose: Mutations in PITX2 are associated with Axenfeld-Rieger syndrome (ARS), which involves ocular, dental and umbilical abnormalities. Identification of cis-regulatory elements of PITX2 is important to better understand the mechanisms of disease. Methods: Conserved noncoding elements surrounding PITX2/pitx2 were identified and examined through transgenic analysis in zebrafish; expression pattern was studied by in situ hybridization. Patient samples were screened for deletion/duplication of the PITX2 upstream region using Affymetrix arrays and TaqMan probes. Results: Zebrafish pitx2 demonstrates conserved expression during ocular and craniofacial development. Thirteen conserved noncoding sequences positioned within a gene desert as far as 1.1-Mb upstream of the human PITX2 gene were identified; eleven of which have enhancer activities consistent with pitx2 expression. Ten elements mediated expression in the developing brain, four regions were active during eye formation and two sequences were associated with craniofacial expression. One region, CE4, located approximately 111-kb upstream of PITX2, directed a complex pattern including expression in the developing eye and craniofacial region, the classic sites affected in ARS. Screening of ARS patients identified a ~7600-kb deletion that begins 106-108-kb upstream of the PITX2 gene, leaving PITX2 intact while removing regulatory elements CE4-CE13. Conclusion: These data suggest the presence of a complex distant regulatory matrix within the gene desert located upstream of PITX2 with an essential role in its activity and provides a possible mechanism for the previous reports of ARS in patients with balanced translocations involving the 4q25 region upstream of PITX2 as well as the current patient with an upstream deletion.