Family score as an indicator of genetic risk of primary open-angle glaucoma

Objectives: To assess the genetic risk of open-angle glaucoma (OAG) in individuals by calculating a family score (FS), which summarizes the information of all relatives including their disease status, age, sex, and degree of kinship and to examine the genetic contribution to OAG with and without an increased intraocular pressure. Methods: Case and control probands, derived from the Rotterdam Study, underwent the same ophthalmologic examination as their relatives. The FS of each proband was the sum of the differences between observed and expected values of OAG for all relatives. The FSs were compared between case and control probands using logistic regression analysis, adjusted for intraocular pressure. Results: Of 37 case probands, 44 (half-) siblings and 86 children were available, and of 83 control probands there were 97 (half-) siblings and 155 children. Family scores ranged from -0.44 to 7.08 in case probands and from -0.98 to 2.46 in control probands. One unit increase in FS was significantly associated with a higher risk of OAG (odds ratio, 1.59; 95% confidence interval, 1.14-2.23). Adjustments for intraocular pressure did not change the odds ratio. Conclusions: These data show that the FS strongly predicts OAG, independent of the intraocular pressure. Therefore, the FS is useful to identify individuals with a high genetic risk.