title: Mitochondrial haplogroups are associated with severity of diabetic retinopathy.
abstract: OBJECTIVE
  To determine if specific mitochondrial haplogroups associate with nonproliferative diabetic retinopathy (NPDR) and proliferative diabetic retinopathy (PDR).
  
  
  METHODS
  Deidentified medical records for Caucasian patients with diabetic retinopathy (DR; 153 NPDR and 138 PDR) were obtained from BioVU, Vanderbilt University's electronic, deidentified DNA databank. An independent cohort of Caucasian patients with DR (44 NPDR and 57 PDR) from the Vanderbilt Eye Institute (VEI) was used for validation. We tested for an association between mitochondrial haplogroups and PDR among patients with DR.
  
  
  RESULTS
  In the BioVU cohort, PDR frequency among Caucasian DR patients differed significantly by mitochondrial haplogroup (P = 0.027). Replication in the VEI cohort confirmed this association (P = 0.0064). In the combined cohort, patients from the common haplogroup H were more likely to have PDR (odds ratio [OR] = 2.0 [95% confidence interval (CI) = 1.3-3.0], P = 0.0012), while patients from haplogroup Uk were less likely to have PDR (OR = 0.5 [95% CI = 0.3-0.8], P = 0.0049). In logistic regression analyses, the addition of diabetes duration, hemoglobin A1c (HgbA1c) levels, and hypertension had no effect on the associations of haplogroups H and Uk with PDR.
  
  
  CONCLUSIONS
  In this study, DR patients from mitochondrial haplogroup H were more likely to have PDR, while DR patients from haplogroup Uk were less likely to have PDR. The association was independent of the major clinical variables affecting PDR. The mitochondrial haplogroups were as strong a risk factor for PDR as were elevated HgbA1c levels.
authors.affiliation: Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee, United States.
authors.forename: Christopher B
authors.initials: CB
authors.lastname: Estopinal
authors.affiliation: Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee, United States.
authors.forename: Isaac M
authors.initials: IM
authors.lastname: Chocron
authors.affiliation: Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee, United States.
authors.forename: Megan B
authors.initials: MB
authors.lastname: Parks
authors.affiliation: Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee, United States.
authors.forename: Emily A
authors.initials: EA
authors.lastname: Wade
authors.affiliation: Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee, United States.
authors.forename: Rachel M
authors.initials: RM
authors.lastname: Roberson
authors.affiliation: Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee, United States.
authors.forename: L Goodwin
authors.initials: LG
authors.lastname: Burgess
authors.affiliation: Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee, United States.
authors.forename: Milam A
authors.initials: MA
authors.lastname: Brantley
authors.affiliation: Center for Human Genetics Research and Department of Molecular Physiology and Biophysics, Vanderbilt University Medical Center, Nashville, Tennessee, United States.
authors.forename: David C
authors.initials: DC
authors.lastname: Samuels
mesh_terms: D000328:Adult; D000368:Aged; D016022:Case-Control Studies; D015331:Cohort Studies; D003922:Diabetes Mellitus, Type 1 / Q000150:complications; D003924:Diabetes Mellitus, Type 2 / Q000150:complications; D003930:Diabetic Retinopathy / Q000097:blood / Q000235:genetics*; D005260:Female; D005838:Genotype; D006442:Glycated Hemoglobin / Q000032:analysis; D006239:Haplotypes; D006801:Humans; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000235:genetics*; D016017:Odds Ratio
chemical_list: D006442:Glycated Hemoglobin
keywords: diabetes; diabetic retinopathy; genetics; mitochondrial DNA; mitochondrial genetics; mitochondrial haplogroup; proliferative diabetic retinopathy