Table 2 Conditional probabilities (p) for retinal arterial tortuosity in 57 monozygotic twin pairs
p(Twin status|co-twin status)Co-twin status of tortuosity
Twin status of tortuosityCategory 1Category 2Category 3
Category 10.72 (0.53 to 0.86)0.17 (0.09 to 0.29)0.01 (0.00 to 0.11)
Category 20.28 (0.14 to 0.47)0.71 (0.57 to 0.83)0.37 (0.16 to 0.64)
Category 30.00 (0.00 to 0.00)0.12 (0.05 to 0.23)0.63 (0.35 to 0.83)

  • Numbers are given as probability p (95% confidence interval).

  • Category 1 = straight retinal arteries, category 2 = wavy retinal arteries, and category 3 = tortuous retinal arteries.