Heritability of Retinal Vascular Fractals: A Twin Study

Anna Stage Vergmann, Rebecca Broe, Line Kessel, Jesper Leth Hougaard, Sören Möller, Kirsten Ohm Kyvik, Michael Larsen, Inger Christine Munch, Jakob Grauslund

4 Citations (Scopus)


Purpose: To determine the genetic contribution to the pattern of retinal vascular branching expressed by its fractal dimension.

Methods: This was a cross-sectional study of 50 monozygotic and 49 dizygotic, same-sex twin pairs aged 20 to 46 years. In 50°, disc-centered fundus photographs, the retinal vascular fractal dimension was measured using the box-counting method and compared within monozygotic and dizygotic twin pairs using Pearson correlation coefficients. Falconer's formula and quantitative genetic models were used to determine the genetic component of variation.

Results: The mean fractal dimension did not differ statistically significantly between monozygotic and dizygotic twin pairs (1.505 vs. 1.495, P = 0.06), supporting that the study population was suitable for quantitative analysis of heritability. The intrapair correlation was markedly higher (0.505, P = 0.0002) in monozygotic twins than in dizygotic twins (0.108, P = 0.46), corresponding to a heritability h2 for the fractal dimension of 0.79. In quantitative genetic models, dominant genetic effects explained 54% of the variation and 46% was individually environmentally determined.

Conclusions: In young adult twins, the branching pattern of the retinal vessels demonstrated a higher structural similarity in monozygotic than in dizygotic twin pairs. The retinal vascular fractal dimension was mainly determined by genetic factors, which accounted for 54% of the variation. The genetically predetermination of the retinal vasculature may affect the retinal response to potential vascular disease in later life.

Original languageEnglish
JournalInvestigative ophthalmology & visual science
Issue number10
Pages (from-to)3997-4002
Number of pages6
Publication statusPublished - 2017


  • Adult
  • Cross-Sectional Studies
  • Female
  • Fractals
  • Humans
  • Male
  • Middle Aged
  • Quantitative Trait, Heritable
  • Retinal Vessels
  • Surveys and Questionnaires
  • Twins, Dizygotic
  • Twins, Monozygotic
  • Young Adult
  • Journal Article
  • Twin Study


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