Patients with X-linked retinitis pigmentosa due to RPGR mutations lose visual acuity and visual field more rapidly than do patients with dominant retinitis pigmentosa due to RHO mutations.

To determine whether a therapeutic dose of docosahexaenoic acid (DHA), an-3 fatty acid, will slow the course of retinal degeneration in adult patients with retinitis pigmentosa who are also receiving vitamin A. Design: Randomized, controlled, double-masked trial of 221 patients, aged 18 to 55 years, evaluated over a 4-year interval. Patients were given either 1200 mg/d of docosahexaenoic acid or control capsules. All were given 15000 IU/d of vitamin A (given as retinyl palmitate). Randomization considered genetic type and baseline dietary-3 fatty acid intake. Main Outcome Measures: The primary outcome measure was the total point score for the 30-2 program of the Humphrey field analyzer; secondary outcome measures were the total point score for the 30-2 and 30/60-1 programs combined, 30-Hz electroretinogram amplitude, and Early Treatment Diabetic Rentinopathy Study visual acuity. Results: No significant differences in decline in ocular function were found between the docosahexaenoic

INTRODUCTION Spinocerebellar ataxia type 7 is a neurodegenerative polyglutamine disease characterized by ataxia and retinal degeneration. The longitudinal course is unknown, and relationships between repeat expansion, clinical manifestations, and neuropathology remain uncertain. METHODS We followed 16 affected individuals of a 61-member kindred over 27 years with electroretinograms, neurological examinations including the Brief Ataxia Rating Scale, neuroimaging in 5, and autopsy in 4 cases. RESULTS We identified 4 stages of the illness. Stage 0; gene positive but phenotypically silent. Stage 1; no symptoms, but hyperreflexia and/or abnormal electroretinograms. Stage 2; symptoms and signs progress modestly. Stage 3; rapid clinical progression. CAG repeat length correlated inversely with age of onset of visual or motor signs (r=-0.74, p=0.002). Stage 3 rate of progression did not differ between cases (p=0.18). Electroretinograms correlated with Brief Ataxia Rating Scale score and were a biomarker of disease onset and progression. All symptomatic patients developed gait ataxia, extremity dysmetria, dysarthria, dysrhythmia, and oculomotor abnormalities. Funduscopy revealed pale optic discs and pigmentary disturbances. Visual acuity declined to blindness in those with longer CAG expansions. Hyperreflexia was present from Stage 1 onwards. Restless legs syndrome and sensory impairment were common. Neuropathological hallmarks were neuronal loss in cerebellar cortex, deep cerebellar nuclei, inferior olive, and anterior horns of the spinal cord, and axonal loss in spinocerebellar tracts, dorsal nerve roots and posterior columns. Retinal pathology included photoreceptor degeneration and disruption of retinal pigment epithelium. DISCUSSION Spinocerebellar ataxia type 7 evolves through 4 clinical stages; neuropathological findings underlie the clinical presentation; electroretinograms are a potential biomarker of disease progression.

Purpose To estimate the mean rates of ocular function loss in patients with autosomal recessive retinitis pigmentosa due to USH2A mutations. Methods In 125 patients with USH2A mutations, we used longitudinal regression to estimate mean rates of change of Snellen visual acuity, Goldmann visual field area (V4e white test light), and 30 Hz (cone) full-field electroretinogram amplitude. We compared these rates to those of previously studied cohorts with dominant retinitis pigmentosa due to RHO mutations and with X-linked retinitis pigmentosa due to RPGR mutations. We also compared rates of change in patients with the Cys759Phe mutation, the USH2A mutation associated with nonsyndromic disease, with rates of change in patients with the Glu767fs mutation, the most common USH2A mutation associated with Usher syndrome, type II (i.e., retinitis pigmentosa and hearing loss). Results Mean annual exponential rates of decline for the USH2A patients were 2.6% for visual acuity, 7.0% for visual field area, and 13.2% for electroretinogram amplitude. The rate of acuity loss fell between the corresponding rates for the RHO and RPGR patients, while the rates for field and ERG amplitude loss were faster than those for the RHO and RPGR patients. No significant differences were found for patients with the Cys759Phe mutation versus patients with the Glu767fs mutation. Conclusions On average, USH2A patients lose visual acuity faster than RHO patients and slower than RPGR patients. USH2A patients lose visual field and cone electroretinogram amplitude faster than RHO patients and RPGR patients. Patients with a nonsyndromic USH2A mutation have the same retinal disease course as patients with syndromic USH2A disease.

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These phenotypic differences can help guide genetic testing and genetic counseling for patients with this syndrome.

Purpose To determine the frequency and severity of visual function loss in female carriers of X-linked retinitis pigmentosa (XLRP). Design Case series. Participants XLRP carriers with cross-sectional data (n = 242) and longitudinal data (n = 34, median follow-up: 16 years, follow-up range: 3–37 years). Half of the carriers were from RPGR- or RP2-genotyped families. Methods Retrospective medical records review. Main Outcome Measures Visual acuities, visual field areas, final dark adaptation thresholds, and full-field ERGs to 0.5 Hz and 30 Hz flashes. Results In genotyped families, 40% of carriers showed a baseline abnormality on at least one of the three psychophysical tests. There was a wide range of function among carriers; for example 3 of 121 (2%) of genotyped carriers were legally blind due to poor visual acuity, some as young as 35 years of age. Visual fields were less affected than visual acuity. In all carriers, the average ERG amplitude to 30 Hz flashes was about 50% of normal, and the average exponential rate of amplitude loss over time was half that of XLRP males (3.7%/year vs 7.4%/year, respectively). Among obligate carriers with affected fathers and/or sons, 53 of 55 (96%) had abnormal baseline ERGs. Some carriers who initially had completely normal fundi in both eyes went on to develop moderately decreased vision, though not legal blindness. Among carriers with RPGR mutations, those with mutations in ORF15, compared to those in exons 1–14, had worse final dark adaptation thresholds and lower 0.5 Hz and 30 Hz ERG amplitudes. Conclusions Most carriers of XLRP had mildly or moderately reduced visual function but rarely became legally blind. In most cases, obligate carriers could be identified by ERG testing. Carriers of RPGR ORF15 mutations tended to have worse visual function than carriers of RPGR exon 1–14 mutations. Since XLRP carrier ERG amplitudes and decay rates over time were on average half of those of affected males, these observations were consistent with the Lyon hypothesis of random X-inactivation.

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