Heritability of Retinal Vascular Fractals: A Twin Study

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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 - Aug 2017

    Research areas

  • 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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