Heritability of Retinal Vascular Fractals: A Twin Study

TY - JOUR

T1 - Heritability of Retinal Vascular Fractals

T2 - A Twin Study

AU - Vergmann, Anna Stage

AU - Broe, Rebecca

AU - Kessel, Line

AU - Hougaard, Jesper Leth

AU - Möller, Sören

AU - Kyvik, Kirsten Ohm

AU - Larsen, Michael

AU - Munch, Inger Christine

AU - Grauslund, Jakob

PY - 2017/8

Y1 - 2017/8

N2 - 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 50º, 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.

AB - 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 50º, 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.

KW - Adult

KW - Cross-Sectional Studies

KW - Female

KW - Fractals

KW - Humans

KW - Male

KW - Middle Aged

KW - Quantitative Trait, Heritable

KW - Retinal Vessels

KW - Surveys and Questionnaires

KW - Twins, Dizygotic

KW - Twins, Monozygotic

KW - Young Adult

KW - Journal Article

KW - Twin Study

U2 - 10.1167/iovs.17-22072

DO - 10.1167/iovs.17-22072

M3 - Journal article

C2 - 28800646

SN - 0146-0404

VL - 58

SP - 3997

EP - 4002

JO - Investigative Ophthalmology & Visual Science

JF - Investigative Ophthalmology & Visual Science

IS - 10

ER -