Abstract
Abstract: :
Purpose: To relate the rate of progression of retinal degeneration in patients with retinitis pigmentosa due to dominant rhodopsin mutations to the location of the affected amino acid according to a new three-dimensional model of rhodopsin derived from high-resolution crystallography (Palczewski et al, Science 2000;289:739). Methods: We followed the change in Snellen visual acuity, Goldmann visual field area, and full-field cone ERG amplitude for an average of 8.7 years in 140 patients (a total of 826 examinations), each with 1 of 29 rhodopsin mutations. We were able to group 101 patients (72%) according to whether their affected amino acid was in the globular N-terminus (residues 1-33), the plug region (residues 110 and 173-198), or the C-terminus (residues 324-348) and compared the mean exponential annual rates of change by group after adjusting for age, gender, and baseline function. Results: The mean rates of decline were 1.5% for visual acuity, 2.2% for visual field area, and 5.9% for ERG amplitude based on all of the patients. Each of these rates was significantly different from that predicted by a cross-sectional analysis of baseline visits. The mean rate of acuity loss was faster for the group with mutations affecting the plug (4.9%) than for the globule group (2.0%) or C-terminus group (1.8%) (p=0.02 and p=0.04, respectively). The mean rate of field loss was faster for the C-terminus group (7.4%) than for the globule group (1.3%) or plug group (2.7%) (p<0.001 and p=0.03, respectively). The mean rate of ERG decline was also faster for the C-terminus group (13.0%) than for the globule group (4.8%) or plug group (2.3%) (p<0.001 in both cases). Conclusion: Mean rates of decline of visual acuity, visual field area, and ERG amplitude vary with the region affected by a rhodopsin mutation. The rate of visual acuity loss is fastest in patients with mutations affecting the plug, while the rates of visual field and ERG loss are fastest in patients with mutations affecting the C-terminus.
Keywords: 562 retinal degenerations: hereditary • 352 clinical (human) or epidemiologic studies: natural history • 480 mutations