Association of the CYP39A1 G204E Genetic Variant with Increased Risk of Glaucoma and Blindness in Patients with Exfoliation Syndrome

Purpose: Carriers of functionally deficient mutations in the CYP39A1 gene have been recently reported to have a 2-fold increased risk of exfoliation syndrome (XFS). The aim of this study was to evaluate the risk of blindness and related clinical phenotypes of XFS patients carrying the loss-of-function CYP39A1 G204E mutation in comparison with XFS patients without any CYP39A1 mutation.

Design: Retrospective case study.

Participants: A total of 35 patients diagnosed with XFS carrying the CYP39A1 G204E mutation and 150 XFS patients without any CYP39A1 mutation who were randomly selected from the Japanese XFS cohort.

Methods: Two-sided Fisher exact test with an alpha level < 0.05 was used to estimate the significance of the calculated odds ratio (OR) for all categorical measures. Comparisons between groups of subjects were performed using linear mixed effect models with group as random effect and taking possible dependence between eyes within a subject into account.

Main outcome measures: Primary analysis compared the incidence of blindness (defined as visual acuity [VA] < 0.05 decimal), prevalence of exfoliation glaucoma (XFG), history of glaucoma surgery, and indices of glaucoma severity such as visual field (VF) mean deviation (MD), intraocular pressure (IOP), and vertical cup-disc ratio (CDR) between CYP39A1 G204E carriers and those without any CYP39A1 mutation.

Results: The overall risk for blindness was significantly higher in XFS patients carrying the CYP39A1 G204E variant (10/35 [28.6%]) compared with XFS patients without any CYP39A1 mutations (8/150 [5.4%]; odds ratio [OR], 7.1; 95% confidence interval [CI], 2.7-20.2]; P < 0.001). A higher proportion of XFS patients with the CYP39A1 G204E mutation (23/35 [65.7%]) had evidence of XFG in at least 1 eye compared with the comparison group (41/150 [27.3%]; OR, 5.1; 95% CI, 2.4-11.4]; P < 0.0001). Significantly higher peak IOP, larger vertical CDR, and worse VF MD were also found in CYP39A1 G204E variant carriers (P < 0.001). Additionally, patients with the CYP39A1 G204E mutation (18/35 [51.4%]) required more laser or glaucoma surgical interventions compared with those without any CYP39A1 mutation (32/150 [21.3%], P < 0.001).

Conclusions: Patients with XFS carrying the CYP39A1 G204E mutation had significantly increased risk of blindness, higher occurrence of XFG, and more severe glaucoma compared with patients with XFS without any CYP39A1 mutation.