Population-based estimate of the sibling recurrence risk ratio for rhegmatogenous retinal detachment.

PURPOSE The influence of genetic predisposition on nonsyndromic primary rhegmatogenous retinal detachment (RRD) is poorly characterized. The purpose of this study was to investigate the magnitude of genetic risk for RRD. METHODS All participants (probands) in the Scottish Retinal Detachment Study (N = 922) with known postal addresses were contacted by questionnaire to assess the personal and family history of RRD. Sibling affection status was modeled by logistic regression and generalizing estimating equations accounting for the effect of proband covariates of age, sex, spherical equivalent refraction, index birth order, and body mass index (BMI). Sibling-sibling recurrence risk ratios (λs) and parent-offspring recurrence risk ratios were calculated. RESULTS Sixty-five percent of probands returned completed questionnaires. Of these, 602 families (parents, siblings, offspring), 7.8% (47) had one affected member, and 0.5% (3) had two affected members. A total of 501 sibships were included in the regression analysis. The odds ratio (OR) that a sibling would be affected, given another affected sibling, was 1.91 (95% confidence interval [CI], 1.18-3.05). With adjustment for age and sex, the OR that a sibling would be affected increased by 9.8% for each additional diopter of spherical equivalent refractive error (SER) toward myopia in the proband. The λs and the parent-offspring recurrence risk ratio of RRD were 2.1 (95% CI, 1.3-3.2) and 2.9 (95% CI, 1.9-4.2), respectively. CONCLUSIONS Genetic factors are important in the etiology of myopic and nonmyopic RRD. The risk of having an affected sibling with RRD increases twofold, given that a sibling has had the condition. The sibling risk increases with the level of spherical equivalent myopia in the proband.