Choroideremia: new findings from ocular pathology and review of recent literature

Abstract

Histopathology of young individuals affected by choroideremia is rarely available to allow correlation with the clinical presentation. A 30-year-old man with choroideremia died in a motor vehicle accident and one eye was subjected to histopathological examination. Immunoblot analysis of protein derived from white blood cells of a living brother, also affected with choroideremia, confirmed the absence of Rab escort protein-1, the normal CHM gene product. Direct sequencing of the coding region and adjacent splice sites of the CHM gene was undertaken on genomic DNA from the living brother and revealed a transition mutation, C to T, in exon 6 (R253X) which resulted in a stop codon and was predicted to truncate the protein product. Histopathological examination of the eye of the deceased brother showed relative independent degeneration of choriocapillaris, retinal pigment epithelium, and retina, similar to observations in the mouse model of choroideremia. In addition, mild T-lymphocytic infiltration was found within the choroid. The ophthalmic features and the pathology of choroideremia are discussed in light of new findings in the current case.

Fig. 1

Fundus photographs of OD (A) and OS (B) of an 18-year-old CHM-affected man showing symmetrical profound chorioretinal atrophy with preservation of central macula.

Fig. 2

Histopathology of the eye of a 30-year-old CHM-affected man showing A: abrupt transition area from relatively well-preserved structure (arrow) to severe degeneration; B: ectopic nuclei (arrows); C: apparent areas of RPE duplication (arrow); D: occasional rosette formation (arrow).

Fig. 3

Immunohistochemistry of glial fibrillary acidic protein staining in the transition area from relatively normal retina to atrophic retina, and mild T-lymphocyte infiltration of the choroid (arrows).