title: Distinct iris gene expression profiles of primary angle closure glaucoma and primary open angle glaucoma and their interaction with ocular biometric parameters.
abstract: BACKGROUND
  This study aimed to evaluate differences in iris gene expression profiles between primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG) and their interaction with biometric characteristics.
  
  
  METHODS
  Prospective study.
  
  
  METHODS
  Thirty-five subjects with PACG and thirty-three subjects with POAG who required trabeculectomy were enrolled at the Singapore National Eye Centre, Singapore.
  
  
  METHODS
  Iris specimens, obtained by iridectomy, were analysed by real-time polymerase chain reaction for expression of type I collagen, vascular endothelial growth factor (VEGF)-A, -B and -C, as well as VEGF receptors (VEGFRs) 1 and 2. Anterior segment optical coherence tomography (ASOCT) imaging for biometric parameters, including anterior chamber depth (ACD), anterior chamber volume (ACV) and lens vault (LV), was also performed pre-operatively.
  
  
  METHODS
  Relative mRNA levels between PACG and POAG irises, biometric measurements, discriminant analyses using genes and biometric parameters.
  
  
  RESULTS
  COL1A1, VEGFB, VEGFC and VEGFR2 mRNA expression was higher in PACG compared to POAG irises. LV, ACD and ACV were significantly different between the two subgroups. Discriminant analyses based on gene expression, biometric parameters or a combination of both gene expression and biometrics (LV and ACV), correctly classified 94.1%, 85.3% and 94.1% of the original PACG and POAG cases, respectively. The discriminant function combining genes and biometrics demonstrated the highest accuracy in cross-validated classification of the two glaucoma subtypes.
  
  
  CONCLUSIONS
  Distinct iris gene expression supports the pathophysiological differences that exist between PACG and POAG. Biometric parameters can combine with iris gene expression to more accurately define PACG from POAG.
authors.affiliation: Singapore Eye Research Institute, Singapore.|Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.|Duke-NUS Graduate Medical School, Singapore.
authors.forename: Li-Fong
authors.initials: LF
authors.lastname: Seet
authors.affiliation: Singapore National Eye Centre, Singapore.
authors.forename: Arun
authors.initials: A
authors.lastname: Narayanaswamy
authors.affiliation: Singapore Eye Research Institute, Singapore.
authors.forename: Sharon N
authors.initials: SN
authors.lastname: Finger
authors.affiliation: Singapore Eye Research Institute, Singapore.|Duke-NUS Graduate Medical School, Singapore.
authors.forename: Hla M
authors.initials: HM
authors.lastname: Htoon
authors.affiliation: Singapore Eye Research Institute, Singapore.|Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.|Duke-NUS Graduate Medical School, Singapore.
authors.forename: Monisha E
authors.initials: ME
authors.lastname: Nongpiur
authors.affiliation: Singapore Eye Research Institute, Singapore.
authors.forename: Li Zhen
authors.initials: LZ
authors.lastname: Toh
authors.affiliation: Singapore National Eye Centre, Singapore.
authors.forename: Henrietta
authors.initials: H
authors.lastname: Ho
authors.affiliation: Singapore Eye Research Institute, Singapore.|Singapore National Eye Centre, Singapore.
authors.forename: Shamira A
authors.initials: SA
authors.lastname: Perera
authors.affiliation: Singapore Eye Research Institute, Singapore.|Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.|Duke-NUS Graduate Medical School, Singapore.|Singapore National Eye Centre, Singapore.|School of Materials Science and Engineering, Nanyang Technological University, Singapore.
authors.forename: Tina T
authors.initials: TT
authors.lastname: Wong
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000867:Anterior Chamber / Q000473:pathology*; D001699:Biometry; D024042:Collagen Type I / Q000235:genetics; D000090602:Collagen Type I, alpha 1 Chain; D005136:Eye Proteins / Q000235:genetics*; D005260:Female; D020869:Gene Expression Profiling; D015812:Glaucoma, Angle-Closure / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D005902:Glaucoma, Open-Angle / Q000235:genetics* / Q000473:pathology / Q000601:surgery; D006068:Gonioscopy; D006801:Humans; D007429:Intraocular Pressure; D032801:Iridectomy; D007498:Iris / Q000378:metabolism*; D007908:Lens, Crystalline / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D041623:Tomography, Optical Coherence; D014065:Tonometry, Ocular; D042561:Vascular Endothelial Growth Factor B / Q000235:genetics; D042582:Vascular Endothelial Growth Factor C / Q000235:genetics; D040281:Vascular Endothelial Growth Factor Receptor-1 / Q000235:genetics; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000235:genetics
chemical_list: D024042:Collagen Type I; D000090602:Collagen Type I, alpha 1 Chain; D005136:Eye Proteins; D012333:RNA, Messenger; C467485:VEGFB protein, human; C467486:VEGFC protein, human; D042561:Vascular Endothelial Growth Factor B; D042582:Vascular Endothelial Growth Factor C; C000588866:KDR protein, human; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2
keywords: PACG; POAG; biometrics; iris