title: Evaluation of the X-linked high-grade myopia locus (MYP1) with cone dysfunction and color vision deficiencies.
abstract: OBJECTIVE
  X-linked high myopia with mild cone dysfunction and color vision defects has been mapped to chromosome Xq28 (MYP1 locus). CXorf2/TEX28 is a nested, intercalated gene within the red-green opsin cone pigment gene tandem array on Xq28. The authors investigated whether TEX28 gene alterations were associated with the Xq28-linked myopia phenotype. Genomic DNA from five pedigrees (with high myopia and either protanopia or deuteranopia) that mapped to Xq28 were screened for TEX28 copy number variations (CNVs) and sequence variants.
  
  
  METHODS
  To examine for CNVs, ultra-high resolution array-comparative genomic hybridization (array-CGH) assays were performed comparing the subject genomic DNA with control samples (two pairs from two pedigrees). Opsin or TEX28 gene-targeted quantitative real-time gene expression assays (comparative CT method) were performed to validate the array-CGH findings. All exons of TEX28, including intron/exon boundaries, were amplified and sequenced using standard techniques.
  
  
  RESULTS
  Array-CGH findings revealed predicted duplications in affected patient samples. Although only three copies of TEX28 were previously reported within the opsin array, quantitative real-time analysis of the TEX28 targeted assay of affected male or carrier female individuals in these pedigrees revealed either fewer (one) or more (four or five) copies than did related and control unaffected individuals. Sequence analysis of TEX28 did not reveal any variants associated with the disease status.
  
  
  CONCLUSIONS
  CNVs have been proposed to play a role in disease inheritance and susceptibility as they affect gene dosage. TEX28 gene CNVs appear to be associated with the MYP1 X-linked myopia phenotypes.
authors.affiliation: Duke University Eye Center, Durham, North Carolina, USA.
authors.forename: Ravikanth
authors.initials: R
authors.lastname: Metlapally
authors.forename: Michel
authors.initials: M
authors.lastname: Michaelides
authors.forename: Anuradha
authors.initials: A
authors.lastname: Bulusu
authors.forename: Yi-Ju
authors.initials: YJ
authors.lastname: Li
authors.forename: Marianne
authors.initials: M
authors.lastname: Schwartz
authors.forename: Thomas
authors.initials: T
authors.lastname: Rosenberg
authors.forename: David M
authors.initials: DM
authors.lastname: Hunt
authors.forename: Anthony T
authors.initials: AT
authors.lastname: Moore
authors.forename: Stephan
authors.initials: S
authors.lastname: Züchner
authors.forename: Catherine Bowes
authors.initials: CB
authors.lastname: Rickman
authors.forename: Terri L
authors.initials: TL
authors.lastname: Young
mesh_terms: D003117:Color Vision Defects / Q000235:genetics*; D005260:Female; D018628:Gene Dosage; D020869:Gene Expression Profiling; D040181:Genetic Diseases, X-Linked / Q000235:genetics*; D005838:Genotype; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000235:genetics*; D047728:Myopia, Degenerative / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D055355:Opsins / Q000235:genetics; D010375:Pedigree; D012333:RNA, Messenger / Q000235:genetics; D017949:Retinal Cone Photoreceptor Cells / Q000473:pathology*; D012164:Retinal Diseases / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D008565:Membrane Proteins; D055355:Opsins; D012333:RNA, Messenger; C108630:TEX28 protein, human