Purpose: To analyze the variability of clinical and electrophysiological characteristics in X-linked choroideremia and provide the first report of a negative electroretinogram in choroideremia.
Design: Retrospective study.
Participants: The records of 18 male patients with choroideremia and 8 female carriers were evaluated.
Methods: The data were reviewed regarding visual acuity (VA), color vision, perimetry, fundus autofluorescence, and full-field electroretinography (according to standards of the International Society for Clinical Electrophysiology of Vision).
Main outcome measures: Morphological and functional phenotype characteristics, fundus autofluorescence, electroretinography, and Rab escort protein 1 (REP-1) mutations.
Results: Four unrelated families with choroideremia (9 affected males, 7 carriers) and 10 unrelated individuals (9 affected males, 1 carrier) were included. Mutational analysis, performed in 2 families and 3 individual males, revealed REP-1 mutations in all except 1 male. The age of the males ranged from 5.9 to 63.0 years (mean, 33.9), and VA ranged from hand movements to 1.0 (median, 0.7). Fundus autofluorescence (n = 7) showed defects in the retinal pigment epithelium in all males. Electroretinography (n = 13) was almost undetectable in 6 males and reduced in 6, indicating a rod-cone dystrophy. A further male showed a negative electroretinogram, with a b:a wave ratio of 0.5. Visual acuity of the 8 carriers (age, 4.8-56.8 years [mean, 24.0]) ranged from light perception to 1.2 (median, 1.0). Light perception was present in 1 carrier manifesting choroideremia with distinct chorioretinal atrophy. Pigmentary stippling, seen in the other carriers, was seen in fundus autofluorescence (n = 1) with a distinct speckled pattern. Electroretinograms were normal in 6 of 7 and reduced in the manifesting carrier. Defects in color vision and visual field were found in affected males and in the female carriers.
Conclusions: The phenotype of choroideremia presents with high variability. In addition to the previously reported findings, we observed a negative electroretinogram, indicating a postreceptoral retinal dysfunction, in 1 affected male; severe course of choroideremia with early blindness in 1 manifesting carrier; color vision deficits in the majority of affected males and carriers; and characteristic alterations in fundus autofluorescence.