title: Does haptoglobin genotype affect early onset of diabetic retinopathy in patients with type 2 diabetes?
abstract: OBJECTIVE
  There are 2 common alleles for Hp (Hp-1 and Hp-2) and 3 common Hp genotypes: Hp1-1, Hp2-1, and Hp2-2. The haptoglobin genotype may play a dual role in morbidities of diabetes: Hp1-1, protective and Hp2-2, provocative. This study investigated the possible association of haptoglobin genotypes with onset of retinopathy in Type 2 diabetes (DM2).
  
  
  METHODS
  The sample included 98 consecutive adults with DM2 under routine outpatient follow-up from 2007 to 2009 who met the criteria for either no retinopathy at ≥10 years after diagnosis (Group 1) or proliferative retinopathy at ≤10 years after diagnosis (Group 2). Blood samples were collected for haptoglobin genotyping by polymerase chain reaction. Findings were compared between and within groups.
  
  
  RESULTS
  Eighty-four patients had no retinopathy and 14 had early proliferative retinopathy. The distributions of the Hp genotypes were as follows: no-retinopathy group: 28.6% Hp1-1, 35.7% Hp2-1, and 35.7% Hp2-2 and proliferative retinopathy group: 22.6% Hp1-1, 27.4% Hp2-1, and 50% Hp2-2 (NS). On statistical analysis (limited to the larger no-retinopathy group), a predominance of Hp1-1 was noted in older patients; Hp2-2 was associated with an increased rate of stroke.
  
  
  CONCLUSIONS
  The Hp genotype apparently plays no role in the development or worsening of proliferative retinopathy in DM2. Hp1-1 may be involved in delaying the onset of diabetes. Hp2-2 may pose a microvascular risk.
authors.affiliation: Pediatric Ophthalmology Unit, Schneider Children's Medical Center of Israel, Petach Tikva, Israel. ncohen1@gmail.com
authors.forename: Nitza
authors.initials: N
authors.lastname: Goldenberg-Cohen
authors.forename: Merav
authors.initials: M
authors.lastname: Gabbay
authors.forename: Olga
authors.initials: O
authors.lastname: Dratviman-Storobinsky
authors.forename: Ehud
authors.initials: E
authors.lastname: Reich
authors.forename: Ruth
authors.initials: R
authors.lastname: Axer-Siegel
authors.forename: Dov
authors.initials: D
authors.lastname: Weinberger
authors.forename: Uri
authors.initials: U
authors.lastname: Gabbay
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003924:Diabetes Mellitus, Type 2 / Q000175:diagnosis*; D003930:Diabetic Retinopathy / Q000175:diagnosis / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006242:Haptoglobins / Q000235:genetics*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009887:Ophthalmoscopy; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012307:Risk Factors
chemical_list: C485359:HP protein, human; D006242:Haptoglobins