Purpose: To clarify the pathogenesis of choroideremia.
Study design: Human tissue study. TISSUES: Eyes of an 88-year-old symptomatic female carrier of choroideremia (CHM) and six normal, age-matched donors.
Methods: The eyes were processed for histopathologic examination, including immunocytochemistry with an antibody against the CHM gene product, REP-1, and retinal cell-specific markers.
Results: The CHM carrier retina showed patchy degeneration, but the photoreceptor and retinal pigment epithelium (RPE) loss appeared to be independent. The choriocapillaris was normal except where retinal areas were severely degenerate. The CHM gene product, REP-1, was localized to the cytoplasm of rods but not cones.
Conclusions: It has generally been considered that photoreceptor degeneration in CHM is secondary to loss of the choriocapillaris or RPE. This study suggests that the rod photoreceptors are a primary site of disease in CHM.