title: Association of apolipoprotein E polymorphisms with normal tension glaucoma in a Chinese population.
abstract: OBJECTIVE
  To evaluate the role of apolipoprotein E (APOE) polymorphisms in primary open angle glaucoma (POAG).
  
  
  METHODS
  A cohort of 400 unrelated Chinese POAG patients was examined, including 294 cases of high tension glaucoma (HTG) and 106 with normal tension glaucoma (NTG). Also studied were 300 unrelated Chinese control subjects. The genotypes of the APOE polymorphisms in exon 4 and in the promoter at positions -491, -427, and -219 were determined by polymerase chain reaction and restriction endonuclease analysis. Frequencies of the genotypes were compared between patients and controls by chi test or Fisher exact test. The association of APOE polymorphisms with POAG phenotypes including age at diagnosis, intraocular pressure (IOP) at diagnosis, highest IOP, cup-disc ratio, and visual field score was investigated by the Kruskal-Wallis test.
  
  
  RESULTS
  No significant difference was detected in the frequencies of APOE promoter polymorphisms between POAG patients and control subjects (P>0.0125). For the exon 4 polymorphism, when compared with control subjects, the frequency of epsilon 4 carriers was significantly lower in patients with NTG (P=0.008; odds ratio=0.36, 95% confidence interval=0.17, 0.79) but not in HTG (P=0.07). Compared with -219TT, the -219G carriers had a significant higher age at diagnosis (P=0.0046). No significant association was found between other APOE polymorphisms and POAG phenotypes (P>0.07).
  
  
  CONCLUSIONS
  Our findings suggest that the APOE epsilon 4 allele confers a protective effect against NTG, whereas the APOE promoter polymorphisms do not contribute to POAG risk. However, the APOE -219G carriers tended to have later-onset POAG.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Chinese University of Hong Kong, Kowloon, Hong Kong.
authors.forename: Ching Yan
authors.initials: CY
authors.lastname: Lam
authors.forename: Bao Jian
authors.initials: BJ
authors.lastname: Fan
authors.forename: Dan Yi
authors.initials: DY
authors.lastname: Wang
authors.forename: Pancy Oi Sin
authors.initials: PO
authors.lastname: Tam
authors.forename: Clement Chee
authors.initials: CC
authors.lastname: Yung Tham
authors.forename: Dexter Yu Lung
authors.initials: DY
authors.lastname: Leung
authors.forename: Dorothy Shu
authors.initials: DS
authors.lastname: Ping Fan
authors.forename: Dennis Shun
authors.initials: DS
authors.lastname: Chiu Lam
authors.forename: Chi Pui
authors.initials: CP
authors.lastname: Pang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D053327:Apolipoprotein E4; D001057:Apolipoproteins E / Q000235:genetics*; D044466:Asian People / Q000235:genetics*; D002648:Child; D005260:Female; D005838:Genotype; D005902:Glaucoma, Open-Angle / Q000208:ethnology / Q000235:genetics*; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D007429:Intraocular Pressure; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012307:Risk Factors
chemical_list: D053327:Apolipoprotein E4; D001057:Apolipoproteins E