title: Endothelial nitric oxide synthase Glu298Asp, 4b/a, and T-786C polymorphisms in type 2 diabetic retinopathy.
abstract: OBJECTIVE
  The possible association between the endothelial nitric oxide (eNOS) gene T-786C (promoter region), 27-bp repeat 4b/4a (intron 4), and Glu298Asp (exon 7) polymorphisms with diabetic retinopathy (DR) was investigated.
  
  
  METHODS
  A retrospective case-control study.
  
  
  METHODS
  A total of 872 type 2 diabetes (T2DM) patients were studied, of whom 383 presented with preproliferative/proliferative retinopathy (DR group), and 489 with absent/mild retinopathy (DWR group).
  
  
  METHODS
  Glu298Asp and T-786C genotyping was carried out by PCR-RFLP analysis, while 4b/4a was assessed by PCR. Genotype distribution was compared using the chi(2)-test, and the contributions of the polymorphisms to DR were analysed by haplotype analysis and multivariate regression analysis.
  
  
  RESULTS
  Lower prevalence of mutant 4a (P = 0.011), and heterozygous 4b/4a (P = 0.042) were seen in the DR compared to the DWR groups; the allele and genotype distribution of the Glu298Asp and T-786C polymorphisms were comparable between DR and DWR groups. Three-loci haplotype analysis demonstrated significant association between eNOS variants and DR, with protective [haplotype 122 (Glu298/4a/-786C)], and susceptible haplotypes [haplotypes 112 (Glu298/4b/-786C) and 222 (Asp298/4a/-786C)] identified. Multivariate regression analysis confirmed the association between haplotypes 122 (P = 0.015); 112 (P = 0.027), and 222 (P = 0.048) and DR, after controlling for potential covariates (including age, sex, age of disease onset; HbA1c; hypertension, total cholesterol).
  
  
  CONCLUSIONS
  This study identifies genetic variation at the eNOS locus as genetic risk factor for diabetic retinopathy, which may serve as a useful marker of increased susceptibility to the risk of retinopathy.
authors.affiliation: Research Unit of Haematological and Autoimmune Diseases, Faculty of Pharmacy, Monastir, Center University, Tunisia.
authors.forename: Intissar
authors.initials: I
authors.lastname: Ezzidi
authors.forename: Nabil
authors.initials: N
authors.lastname: Mtiraoui
authors.forename: Manel Ben Hadj
authors.initials: MB
authors.lastname: Mohamed
authors.forename: Touhami
authors.initials: T
authors.lastname: Mahjoub
authors.forename: Maha
authors.initials: M
authors.lastname: Kacem
authors.forename: Wassim Y
authors.initials: WY
authors.lastname: Almawi
mesh_terms: D000368:Aged; D016022:Case-Control Studies; D003924:Diabetes Mellitus, Type 2; D003930:Diabetic Retinopathy / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D052250:Nitric Oxide Synthase Type III / Q000235:genetics*; D011110:Polymorphism, Genetic; D012189:Retrospective Studies; D012307:Risk Factors
chemical_list: D052250:Nitric Oxide Synthase Type III