Abstract
ObjectiveTo investigate the retinal changes in choroideremia (CHM) patients to determine correlations between age, structure and function.Subjects/MethodsTwenty-six eyes from 13 male CHM patients were included in this prospective longitudinal study. Participants were divided into <50-year (n = 8) and ≥50-year (n = 5) old groups. Patients were seen at baseline, 6-month, and 1-year visits. Optical coherence tomography (OCT), OCT angiography, and fundus autofluorescence were performed to measure central foveal (CFT) and subfoveal choroidal thickness (SCT), as well as areas of preserved choriocapillaris (CC), ellipsoid zone (EZ), and autofluorescence (PAF). Patients also underwent functional investigations including visual acuity (VA), contrast sensitivity (CS), colour testing, microperimetry, dark adaptometry, and handheld electroretinogram (ERG). Vision-related quality-of-life was assessed by using the NEI-VFQ-25 questionnaire.ResultsOver the 1-year follow-up period, progressive loss was detected in SCT, EZ, CC, PAF, and CFT. Those ≥50-years exhibited more structural and functional defects with SCT, EZ, CC, and PAF showing strong correlation with patient age (rho ≤ −0.47, p ≤ 0.02). CS and VA did not change over the year, but CS was significantly correlated with age (rho = −0.63, p = 0.001). Delayed to unmeasurable dark adaptation, decreased colour discrimination and no detectable ERG activity were observed in all patients. Minimal functional deterioration was observed over one year with a general trend of slower progression in the ≥50-years group.ConclusionsQuantitative structural parameters including SCT, CC, EZ, and PAF are most useful for disease monitoring in CHM. Extended follow-up studies are required to determine longitudinal functional changes.
Highlights
Choroideremia (CHM, OMIM 303100) is a rare X-linked progressive chorioretinal dystrophy with an estimated prevalence of 1 in 50,000–100,000 [1, 2]
Choroideremia is caused by mutations in the CHM gene (OMIM 303390) encoding Rab-escort protein 1 (REP1), which is involved in lipid prenylation and intracellular protein trafficking
Genetic variants for study participants are reported in Supplemental Table S1
Summary
Choroideremia (CHM, OMIM 303100) is a rare X-linked progressive chorioretinal dystrophy with an estimated prevalence of 1 in 50,000–100,000 [1, 2]. Choroideremia is caused by mutations in the CHM gene (OMIM 303390) encoding Rab-escort protein 1 (REP1), which is involved in lipid prenylation and intracellular protein trafficking. Over 30% of patients have nonsense mutations [1]. There are no commercially approved treatments available for CHM, with variable results have been reported from adeno-associated virus vector gene therapy clinical trials [5, 6]. Natural history studies of CHM are required to refine clinical trial endpoints and for monitoring disease progression
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