Choroideremia carriers maintain a normal electro-oculogram (EOG)

Abstract

Purpose: To assess the functional integrity of the retinal pigment epithelium and outer retina in choroideremia (CHM) carriers with confirmed mutations in the REP-1 gene, by recording the EOG.

Methods: The visual function of 17 choroideremia carriers ages 25-61 was assessed by determining their Snellen visual acuity and by recording the Arden ratio of the EOG. The 15 exons of the CHM gene were PCR-amplified from DNA from each of the carriers and their sequences were compared to the normal sequence to identify mutations.

Results: The 17 CHM carriers had normal logMAR visual acuity (average of 0.07: Snellen equivalent of 20/25; with no acuities lower than 20/40). The average of the Arden ratio recorded from the 17 carriers was 2.71, which is not significantly different from the average value of 2.46 recorded in our lab. Fundus examination revealed mottled areas of chorioretinal degeneration consistent with the carrier status of CHM. Mutations in the CHM gene were identified in all CHM carriers by sequencing.

Conclusions: Whereas clinical observation suggests that progressive fundus changes are present in female carriers, these carriers do not show a change in the Arden ratio of the EOG over the ages studied (25-61 years).