title: Distribution of ABO and Rh Blood Groups in Patients With Keratoconus: A Case-Control Study.
abstract: Association of keratoconus (KC) with genetic predisposition and environmental factors has been well documented. However, no single study has investigated the possible relationship between ABO and Rh blood groups and KC.
  
  
  METHODS
  A case-control study was designed in a university hospital enrolling 214 patients with KC in the case group and equal number of age- and sex-matched healthy subjects in the control group. Primary characteristics, ABO blood group, and Rh factors were compared between the two groups. Topographic findings of KC eyes and the severity of the diseases were investigated according to the distribution of the blood groups.
  
  
  RESULTS
  Blood group O and Rh(+) phenotype were most frequent in both groups. There was no significant difference between the two groups in terms of ABO blood groups or Rh factors. Mean keratometery (K), central corneal thickness, thinnest corneal thickness, flat K, steep K, sphere and cylinder, spherical equivalent, and uncorrected visual acuity were all similar between ABO blood groups and Rh(+) and Rh(-) groups. However, the best spectacle-corrected visual acuity (BCVA) had the highest value in AB blood group (0.35 ± 0.22 logMAR, P=0.005). Moreover, the blood group AB revealed the highest frequency for grade 3 KC, followed by grades 1, 2, and 4 (P=0.003).
  
  
  CONCLUSIONS
  We observed no significant excess of any particular blood group among KC cases compared with healthy subjects. Except BCVA, none of the keratometric or topographic findings was significantly different between blood groups.
authors.affiliation: Eye Research Center, Farabi Eye Hospital (M.N., M.T.R., S.S., Mor.N., F.R., M.Z.), Tehran University of Medical Sciences, Tehran, Iran; Department of Biotechnology (M.A.K.), College of Science, University of Tehran, Tehran, Iran; and School of Medicine (R.P.), Iran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Naderan
authors.forename: Mohammad Taher
authors.initials: MT
authors.lastname: Rajabi
authors.forename: Saeed
authors.initials: S
authors.lastname: Shoar
authors.forename: Mohammad Amin
authors.initials: MA
authors.lastname: Kamaleddin
authors.forename: Morteza
authors.initials: M
authors.lastname: Naderan
authors.forename: Farzaneh
authors.initials: F
authors.lastname: Rezagholizadeh
authors.forename: Masoome
authors.initials: M
authors.lastname: Zolfaghari
authors.forename: Rozhin
authors.initials: R
authors.lastname: Pahlevani
mesh_terms: D000017:ABO Blood-Group System; D000293:Adolescent; D000328:Adult; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007492:Iran; D007640:Keratoconus / Q000097:blood*; D008297:Male; D008875:Middle Aged; D012204:Rh-Hr Blood-Group System; D012720:Severity of Illness Index; D055815:Young Adult
chemical_list: D000017:ABO Blood-Group System; D012204:Rh-Hr Blood-Group System