Choroideremia: variability of clinical and electrophysiological characteristics and first report of a negative electroretinogram.

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.