title: Heritability of the retinal microcirculation in Flemish families.
abstract: BACKGROUND
  Few population studies have described the heritability and intrafamilial concordance of the retinal microvessels, or the genetic or environmental correlations of the phenotypes of these vessels.
  
  
  METHODS
  We randomly selected 413 participants from 70 families (mean age, 51.5 years; 50.1% women) from a Flemish population. We postprocessed retinal images using IVAN software to generate the central retinal arteriole equivalent (CRAE), central retinal venule equivalent (CRVE), and arteriole-to-venule-ratio (AVR) from these images. We used SAGE version 6.2 and SAS version 9.2 to compute multivariate-adjusted estimates of heritability and intrafamilial correlations of the CRAE, CRVE, and AVR of the retinal microvessels in the images.
  
  
  RESULTS
  Sex, age, mean arterial pressure, and smoking explained up to 12.7% of the variance of the phenotypes of the retinal microvessels of the study participants. With adjustments applied for these covariates, the heritability estimates of CRAE, CRVE, and AVR were 0.213 (P = 0.044), 0.339 (P = 0.010), and 0.272 (P = 0.004), respectively. The parent-offspring correlations for CRAE, CRVE, and AVR were 0.118 (NS), 0.225 (P < 0.01), and 0.215 (P < 0.05), respectively. The corresponding values were 0.222 (P < 0.05), 0.213 (P < 0.05), and 0.390 (P < 0.001) for sib-sib correlations, respectively. The genetic and environmental correlations between CRAE and CRVE were 0.360 and 0.545 (P < 0.001 for both).
  
  
  CONCLUSIONS
  Our study showed moderate heritability for CRAE, CRVE, and AVR, and a significant genetic correlation of CRAE with CRVE in the Flemish population of our study. These findings suggest that genetic factors influence the diameter of the retinal microvessels, and that CRAE and CRVE share some genetic determinants.
authors: Studies Coordinating Centre, Division of Hypertension and Cardiovascular Rehabilitation, Department of Cardiovascular Sciences, University of Leuven, Leuven, Belgium.
authors: Yan-Ping
authors: YP
authors: Liu
authors: Tatiana
authors: T
authors: Kuznetsova
authors: Yu
authors: Y
authors: Jin
authors: Lutgarde
authors: L
authors: Thijs
authors: Kei
authors: K
authors: Asayama
authors: Yu-Mei
authors: YM
authors: Gu
authors: Murielle
authors: M
authors: Bochud
authors: Peter
authors: P
authors: Verhamme
authors: Harry A J
authors: HA
authors: Struijker-Boudier
authors: Jan A
authors: JA
authors: Staessen
mesh_terms: D000328:Adult; D001160:Arterioles / Q000033:anatomy & histology; D001530:Belgium; D006801:Humans; D008833:Microcirculation / Q000235:genetics*; D008875:Middle Aged; D010641:Phenotype; D012171:Retinal Vessels / Q000033:anatomy & histology*; D014699:Venules / Q000033:anatomy & histology
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