Abstract Purpose/Aim: To investigate the relationship of drusen and photoreceptor abnormalities i... more Abstract Purpose/Aim: To investigate the relationship of drusen and photoreceptor abnormalities in African-American (AA) patients with intermediate non-neovascular age-related macular degeneration (AMD). Materials and methods: AA patients with intermediate AMD (n = 11; age 52-77 years) were studied with spectral-domain optical coherence tomography. Macular location and characteristics of large drusen (≥125 µm) were determined. Thickness of photoreceptor laminae was quantified overlying drusen and in other macular regions. A patient with advanced AMD (age 87) was included to illustrate the disease spectrum. Results: In this AA patient cohort, the spectrum of changes known to occur in AMD, including large drusen, sub-retinal drusenoid deposits and geographic atrophy, were identified. In intermediate AMD eyes (n = 17), there were 183 large drusen, the majority of which were pericentral in location. Overlying the drusen there was significant thinning of the photoreceptor outer nuclear layer (termed ONL(+)) as well as the inner and outer segments (IS + OS). The reductions in IS + OS thickness were directly related to ONL(+) thickness. In a fraction (∼8%) of paradrusen locations with normal lamination sampled within ∼280 µm of peak drusen height, ONL(+) was significantly thickened compared to age and retinal-location-matched normal values. Topographical maps of the macula confirmed ONL thickening in regions neighboring and distant to large drusen. Conclusions: We confirm there is a pericentral distribution of drusen across AA-AMD maculae rather than the central localization in Caucasian AMD. Reductions in the photoreceptor laminae overlying drusen are evident. ONL(+) thickening in some macular areas of AA-AMD eyes may be an early phenotypic marker for photoreceptor stress.
To investigate the relationship between photoreceptor layers overlying and adjacent to large drus... more To investigate the relationship between photoreceptor layers overlying and adjacent to large drusen in intermediate nonneovascular AMD. Patients with AMD (n = 41; aged 53-83 years) and elderly control subjects without eye disease (n = 10; aged 51-79 years) were studied with spectral-domain optical coherence tomography. Characteristics of large drusen (≥125 μm) were measured and the thickness of photoreceptor laminae overlying drusen and in retinal regions neighboring the drusen were quantified. There were 750 large drusen in 63 intermediate AMD eyes studied. The width of the drusen sampled averaged 352 μm (SD = 153) and the height averaged 78 μm (SD = 31). There was significant reduction of the photoreceptor outer nuclear layer (ONL) thickness overlying 92% of the drusen. The thickness of the layer corresponding to photoreceptor inner and outer segments above drusen was also reduced, and the reduction was proportional to ONL thickness. In a substantial fraction (~20%) of normally laminated paradrusen locations sampled within ~300 μm of peak drusen height, ONL thickness was significantly increased compared with age and retinal location-matched normal values. Topographical analyses of the macula showed ONL thickening occurring in paradrusen regions as well as retinal locations distant from drusen. Reductions in the photoreceptor laminae overlying drusen were detectable and this is consistent with histological studies revealing neuronal degeneration in AMD. ONL thickening in some macular areas of AMD eyes has not been previously reported and may be an early phenotypic marker for photoreceptor stress, as it has been speculated to be in hereditary retinal degenerations.
To determine the disease expression in autosomal recessive (ar) retinitis pigmentosa (RP) caused ... more To determine the disease expression in autosomal recessive (ar) retinitis pigmentosa (RP) caused by mutations in the MAK (male germ cell-associated kinase) gene. Patients with RP and MAK gene mutations (n = 24; age, 32-77 years at first visit) were studied by ocular examination, perimetry, and optical coherence tomography (OCT). All but one MAK patient were homozygous for an identical truncating mutation in exon 9 and had Ashkenazi Jewish heritage. The carrier frequency of this mutation among 1207 unrelated Ashkenazi control subjects was 1 in 55, making it the most common cause of heritable retinal disease in this population and MAK-associated RP the sixth most common Mendelian disease overall in this group. Visual acuities could be normal into the eighth decade of life. Kinetic fields showed early loss in the superior-temporal quadrant. With more advanced disease, superior and midperipheral function was lost, but the nasal field remained. Only a central island was present at late stages. Pigmentary retinopathy was less prominent in the superior nasal quadrant. Rod-mediated vision was abnormal but detectable in the residual field; all patients had rod>cone dysfunction. Photoreceptor layer thickness was normal centrally but decreased with eccentricity. At the stages studied, there was no evidence of photoreceptor ciliary elongation. The patterns of disease expression in the MAK form of arRP showed some resemblance to patterns described in autosomal dominant RP, especially the form caused by RP1 mutations. The similarity in phenotypes is of interest, considering that there is experimental evidence of interaction between Mak and RP1 in the photoreceptor cilium.
Purpose. To investigate the transitory plateaux observed during dark adaptation after partial ble... more Purpose. To investigate the transitory plateaux observed during dark adaptation after partial bleaches in Sorsby's fundus dystrophy (SFD) and in systemic vitamin A deficiency (VAD). Methods. Psychophysical dark adaptation functions were measured after bleaching exposures isomerizing from 2% to 99% of the rhodopsin. Narrow-band stimuli of 1.7° diameter and 200 msec duration were presented at an eccentricity of 30°. Results.
To evaluate the progression of the earliest stage of disease in ABCA4-associated retinal degenera... more To evaluate the progression of the earliest stage of disease in ABCA4-associated retinal degenerations (RDs). Near-infrared excited reduced-illuminance autofluorescence imaging was acquired across the retina up to 80 degrees eccentricity in 44 patients with two ABCA4 alleles. The eccentricity of the leading disease front (LDF) corresponding to the earliest stage of disease was measured along the four meridians. A mathematical model describing the expansion of the LDF was developed based on 6 years of longitudinal follow-up. The extent of LDF along the superior, inferior, and temporal meridians showed a wide spectrum from 3.5 to 70 degrees. In patients with longitudinal data, the average centrifugal expansion rate was 2 degrees per year. The nasal extent of LDF between the fovea and ONH ranged from 4.3 to 16.5 degrees and expanded at 0.35 degrees per year. The extent of LDF beyond ONH ranged from 19 to 75 degrees and expanded on average at 2 degrees per year. A mathematical model fit...
To characterize the disease expression of an autosomal recessive human retinal degeneration assoc... more To characterize the disease expression of an autosomal recessive human retinal degeneration associated with a mutation in TULP1 (tubby-like protein 1), a gene with currently unknown function. Homozygotes and heterozygotes from an extended Dominican kindred with a TULP1 splice-site gene mutation (IVS14+1,G-->A) were studied clinically and with visual function tests. Sequence analysis of TULP1 was also performed in unrelated patients with severe retinal degeneration from a North American clinic population. Homozygotes had nystagmus, visual acuity of 20/200 or worse, color vision disturbances, bull's eye maculopathy, and peripheral pigmentary retinopathy. Younger patients had a relatively wide extent of kinetic visual fields; older patients had only peripheral islands. No rod function was measurable by psychophysics in any of the patients; markedly reduced cone function was detectable across the visual field of younger patients and in the remaining peripheral islands of older pa...
Purpose. To investigate the transitory plateaux observed during dark adaptation after partial ble... more Purpose. To investigate the transitory plateaux observed during dark adaptation after partial bleaches in Sorsby's fundus dystrophy (SFD) and in systemic vitamin A deficiency (VAD). Methods. Psychophysical dark adaptation functions were measured after bleaching exposures isomerizing from 2% to 99% of the rhodopsin. Narrow-band stimuli of 1.7° diameter and 200 msec duration were presented at an eccentricity of 30°. Results.
We previously developed reduced-illuminance autofluorescence imaging (RAFI) methods involving nea... more We previously developed reduced-illuminance autofluorescence imaging (RAFI) methods involving near-infrared (NIR) excitation to image melanin-based fluorophores and short-wavelength (SW) excitation to image lipofuscin-based flurophores. Here, we propose to normalize NIR-RAFI in order to increase the relative contribution of retinal pigment epithelium (RPE) fluorophores. Retinal imaging was performed with a standard protocol holding system parameters invariant in healthy subjects and in patients. Normalized NIR-RAFI was derived by dividing NIR-RAFI signal by NIR reflectance point-by-point after image registration. Regions of RPE atrophy in Stargardt disease, AMD, retinitis pigmentosa, choroideremia, and Leber congenital amaurosis as defined by low signal on SW-RAFI could correspond to a wide range of signal on NIR-RAFI depending on the contribution from the choroidal component. Retinal pigment epithelium atrophy tended to always correspond to high signal on NIR reflectance. Normalizi...
Leber congenital amaurosis (LCA) is a rare hereditary retinal degeneration caused by mutations in... more Leber congenital amaurosis (LCA) is a rare hereditary retinal degeneration caused by mutations in more than a dozen genes. RPE65, one of these mutated genes, is highly expressed in the retinal pigment epithelium where it encodes the retinoid isomerase enzyme essential for the production of chromophore which forms the visual pigment in rod and cone photoreceptors of the retina. Congenital loss of chromophore production due to RPE65-deficiency together with progressive photoreceptor degeneration cause severe and progressive loss of vision. RPE65-associated LCA recently gained recognition outside of specialty ophthalmic circles due to early success achieved by three clinical trials of gene therapy using recombinant adeno-associated virus (AAV) vectors. The trials were built on multitude of basic, pre-clinical and clinical research defining the pathophysiology of the disease in human subjects and animal models, and demonstrating the proof-of-concept of gene (augmentation) therapy. Subst...
Dramatic restoration of retinal function has followed subretinal viral-mediated gene therapy in R... more Dramatic restoration of retinal function has followed subretinal viral-mediated gene therapy in RPE65-deficient animal models of human Leber congenital amaurosis (LCA) caused by RPE65 mutations. Progress in early-phase clinical trials of RPE65-LCA prompted us to begin development of an in vivo bioassay of clinical grade vector stability for later-phase trials. Naturally-occurring Rpe65-mutant rd12 mice (2-4 mo of age) were studied with full-field electroretinograms (ERGs). Flash stimuli (range, -4.1 to 3.6 log scot-cd x s x m(-2)) were used to evoke ERGs in anesthetized, dark-adapted mice. B-wave amplitudes were measured conventionally and luminance-response functions were fit. Leading edges of photoresponses were analyzed with a model of rod phototransduction activation. A unilateral subretinal injection of AAV2-CB(SB)-hRPE65 vector was delivered and therapeutic efficacy of 4 doses spanning a 2 log unit range was studied with ERGs performed about 6 weeks after injection. Uninjected...
We have been engaged in an ongoing study to screen candidate genes for mutations in small familie... more We have been engaged in an ongoing study to screen candidate genes for mutations in small families with various forms of autosomal recessive retinal dystrophy. Here we report the screening of a cohort of 14 families from Sardinia for mutations in the genes encoding the alpha- and beta-subunits of cGMP-phosphodiesterase and RPE65 (PDE6A, PDE6B, and RPE65). Haplotype analysis was performed on each family using simple sequence repeat markers closely flanking or within each of the three gene candidates. For families in which a gene could not be ruled out from segregating with disease, exons of the gene from proband DNAs were screened for mutations by SSCPE (single strand conformation polymorphism electrophoresis). All variants found by SSCPE were sequenced directly. By haplotype analysis, 6/14, 11/14, and 4/13 families were ruled out for PDE6A, PDE6B, and RPE65, respectively. A few variants were found in the proband DNAs of the remaining families, but only one was significant: a 20 bp d...
CONCLUSIONS. These psychophysical results are consistent with histopathologic findings of a selec... more CONCLUSIONS. These psychophysical results are consistent with histopathologic findings of a selec- tive vulnerability for parafoveal rod photoreceptors in AMD. The different patterns of rod and cone system losses among patients at similar clinical stages reinforces the notion that AMD is a group of disorders with underlying heterogeneity of mechanism of visual loss. Dark-adapted macula-wide testing may be a useful
To characterize the disease expression of an autosomal recessive human retinal degeneration assoc... more To characterize the disease expression of an autosomal recessive human retinal degeneration associated with a mutation in TULP1 (tubby-like protein 1), a gene with currently unknown function. Homozygotes and heterozygotes from an extended Dominican kindred with a TULP1 splice-site gene mutation (IVS14+1,G-->A) were studied clinically and with visual function tests. Sequence analysis of TULP1 was also performed in unrelated patients with severe retinal degeneration from a North American clinic population. Homozygotes had nystagmus, visual acuity of 20/200 or worse, color vision disturbances, bull's eye maculopathy, and peripheral pigmentary retinopathy. Younger patients had a relatively wide extent of kinetic visual fields; older patients had only peripheral islands. No rod function was measurable by psychophysics in any of the patients; markedly reduced cone function was detectable across the visual field of younger patients and in the remaining peripheral islands of older pa...
To investigate the transitory plateaux observed during dark adaptation after partial bleaches in ... more To investigate the transitory plateaux observed during dark adaptation after partial bleaches in Sorsby's fundus dystrophy (SFD) and in systemic vitamin A deficiency (VAD). Psychophysical dark adaptation functions were measured after bleaching exposures isomerizing from 2% to 99% of the rhodopsin. Narrow-band stimuli of 1.7 degrees diameter and 200 msec duration were presented at an eccentricity of 30 degrees. After a full bleach, the patients showed typical dark adaptation abnormalities reported for these diseases. The cone recovery was slowed, and the time to the rod-cone break was delayed; the final phase of rod recovery was also slowed but led to a normal final rod threshold. After partial bleaches, short wavelength stimuli produced a biphasic recovery function, with an initial rapid component and plateau, followed by a subsequent break-off and eventual return to prebleach thresholds. Action spectra obtained during the plateaux were consistent with thresholds for shorter wav...
To correlate retinal histopathology with functional changes caused by the rhodopsin Q64ter mutati... more To correlate retinal histopathology with functional changes caused by the rhodopsin Q64ter mutation. A 50-year-old female heterozygote was evaluated clinically and with psychophysical and electroretinographic measurements of rod and cone function. The retinas obtained after death were examined microscopically, including immunolabeling with antibodies against the C- and N-termini of rhodopsin. On clinical examination 4 months before death, patient's acuity was 20/60, and she had midperipheral scotomas with retained function centrally and in the far periphery. The rod electroretinogram (ERG) was undetectable, and the cone ERG was reduced in amplitude with abnormal receptoral and postreceptoral responses. A previous study of the phenotype of mildly affected family members of the donor suggested that the rod outer segments (ROS) were shortened and that only wild-type rhodopsin was functional. The retinas contained only scattered cones in the midperiphery; the maculas and far periphe...
Abstract Purpose/Aim: To investigate the relationship of drusen and photoreceptor abnormalities i... more Abstract Purpose/Aim: To investigate the relationship of drusen and photoreceptor abnormalities in African-American (AA) patients with intermediate non-neovascular age-related macular degeneration (AMD). Materials and methods: AA patients with intermediate AMD (n = 11; age 52-77 years) were studied with spectral-domain optical coherence tomography. Macular location and characteristics of large drusen (≥125 µm) were determined. Thickness of photoreceptor laminae was quantified overlying drusen and in other macular regions. A patient with advanced AMD (age 87) was included to illustrate the disease spectrum. Results: In this AA patient cohort, the spectrum of changes known to occur in AMD, including large drusen, sub-retinal drusenoid deposits and geographic atrophy, were identified. In intermediate AMD eyes (n = 17), there were 183 large drusen, the majority of which were pericentral in location. Overlying the drusen there was significant thinning of the photoreceptor outer nuclear layer (termed ONL(+)) as well as the inner and outer segments (IS + OS). The reductions in IS + OS thickness were directly related to ONL(+) thickness. In a fraction (∼8%) of paradrusen locations with normal lamination sampled within ∼280 µm of peak drusen height, ONL(+) was significantly thickened compared to age and retinal-location-matched normal values. Topographical maps of the macula confirmed ONL thickening in regions neighboring and distant to large drusen. Conclusions: We confirm there is a pericentral distribution of drusen across AA-AMD maculae rather than the central localization in Caucasian AMD. Reductions in the photoreceptor laminae overlying drusen are evident. ONL(+) thickening in some macular areas of AA-AMD eyes may be an early phenotypic marker for photoreceptor stress.
To investigate the relationship between photoreceptor layers overlying and adjacent to large drus... more To investigate the relationship between photoreceptor layers overlying and adjacent to large drusen in intermediate nonneovascular AMD. Patients with AMD (n = 41; aged 53-83 years) and elderly control subjects without eye disease (n = 10; aged 51-79 years) were studied with spectral-domain optical coherence tomography. Characteristics of large drusen (≥125 μm) were measured and the thickness of photoreceptor laminae overlying drusen and in retinal regions neighboring the drusen were quantified. There were 750 large drusen in 63 intermediate AMD eyes studied. The width of the drusen sampled averaged 352 μm (SD = 153) and the height averaged 78 μm (SD = 31). There was significant reduction of the photoreceptor outer nuclear layer (ONL) thickness overlying 92% of the drusen. The thickness of the layer corresponding to photoreceptor inner and outer segments above drusen was also reduced, and the reduction was proportional to ONL thickness. In a substantial fraction (~20%) of normally laminated paradrusen locations sampled within ~300 μm of peak drusen height, ONL thickness was significantly increased compared with age and retinal location-matched normal values. Topographical analyses of the macula showed ONL thickening occurring in paradrusen regions as well as retinal locations distant from drusen. Reductions in the photoreceptor laminae overlying drusen were detectable and this is consistent with histological studies revealing neuronal degeneration in AMD. ONL thickening in some macular areas of AMD eyes has not been previously reported and may be an early phenotypic marker for photoreceptor stress, as it has been speculated to be in hereditary retinal degenerations.
To determine the disease expression in autosomal recessive (ar) retinitis pigmentosa (RP) caused ... more To determine the disease expression in autosomal recessive (ar) retinitis pigmentosa (RP) caused by mutations in the MAK (male germ cell-associated kinase) gene. Patients with RP and MAK gene mutations (n = 24; age, 32-77 years at first visit) were studied by ocular examination, perimetry, and optical coherence tomography (OCT). All but one MAK patient were homozygous for an identical truncating mutation in exon 9 and had Ashkenazi Jewish heritage. The carrier frequency of this mutation among 1207 unrelated Ashkenazi control subjects was 1 in 55, making it the most common cause of heritable retinal disease in this population and MAK-associated RP the sixth most common Mendelian disease overall in this group. Visual acuities could be normal into the eighth decade of life. Kinetic fields showed early loss in the superior-temporal quadrant. With more advanced disease, superior and midperipheral function was lost, but the nasal field remained. Only a central island was present at late stages. Pigmentary retinopathy was less prominent in the superior nasal quadrant. Rod-mediated vision was abnormal but detectable in the residual field; all patients had rod>cone dysfunction. Photoreceptor layer thickness was normal centrally but decreased with eccentricity. At the stages studied, there was no evidence of photoreceptor ciliary elongation. The patterns of disease expression in the MAK form of arRP showed some resemblance to patterns described in autosomal dominant RP, especially the form caused by RP1 mutations. The similarity in phenotypes is of interest, considering that there is experimental evidence of interaction between Mak and RP1 in the photoreceptor cilium.
Purpose. To investigate the transitory plateaux observed during dark adaptation after partial ble... more Purpose. To investigate the transitory plateaux observed during dark adaptation after partial bleaches in Sorsby's fundus dystrophy (SFD) and in systemic vitamin A deficiency (VAD). Methods. Psychophysical dark adaptation functions were measured after bleaching exposures isomerizing from 2% to 99% of the rhodopsin. Narrow-band stimuli of 1.7° diameter and 200 msec duration were presented at an eccentricity of 30°. Results.
To evaluate the progression of the earliest stage of disease in ABCA4-associated retinal degenera... more To evaluate the progression of the earliest stage of disease in ABCA4-associated retinal degenerations (RDs). Near-infrared excited reduced-illuminance autofluorescence imaging was acquired across the retina up to 80 degrees eccentricity in 44 patients with two ABCA4 alleles. The eccentricity of the leading disease front (LDF) corresponding to the earliest stage of disease was measured along the four meridians. A mathematical model describing the expansion of the LDF was developed based on 6 years of longitudinal follow-up. The extent of LDF along the superior, inferior, and temporal meridians showed a wide spectrum from 3.5 to 70 degrees. In patients with longitudinal data, the average centrifugal expansion rate was 2 degrees per year. The nasal extent of LDF between the fovea and ONH ranged from 4.3 to 16.5 degrees and expanded at 0.35 degrees per year. The extent of LDF beyond ONH ranged from 19 to 75 degrees and expanded on average at 2 degrees per year. A mathematical model fit...
To characterize the disease expression of an autosomal recessive human retinal degeneration assoc... more To characterize the disease expression of an autosomal recessive human retinal degeneration associated with a mutation in TULP1 (tubby-like protein 1), a gene with currently unknown function. Homozygotes and heterozygotes from an extended Dominican kindred with a TULP1 splice-site gene mutation (IVS14+1,G-->A) were studied clinically and with visual function tests. Sequence analysis of TULP1 was also performed in unrelated patients with severe retinal degeneration from a North American clinic population. Homozygotes had nystagmus, visual acuity of 20/200 or worse, color vision disturbances, bull's eye maculopathy, and peripheral pigmentary retinopathy. Younger patients had a relatively wide extent of kinetic visual fields; older patients had only peripheral islands. No rod function was measurable by psychophysics in any of the patients; markedly reduced cone function was detectable across the visual field of younger patients and in the remaining peripheral islands of older pa...
Purpose. To investigate the transitory plateaux observed during dark adaptation after partial ble... more Purpose. To investigate the transitory plateaux observed during dark adaptation after partial bleaches in Sorsby's fundus dystrophy (SFD) and in systemic vitamin A deficiency (VAD). Methods. Psychophysical dark adaptation functions were measured after bleaching exposures isomerizing from 2% to 99% of the rhodopsin. Narrow-band stimuli of 1.7° diameter and 200 msec duration were presented at an eccentricity of 30°. Results.
We previously developed reduced-illuminance autofluorescence imaging (RAFI) methods involving nea... more We previously developed reduced-illuminance autofluorescence imaging (RAFI) methods involving near-infrared (NIR) excitation to image melanin-based fluorophores and short-wavelength (SW) excitation to image lipofuscin-based flurophores. Here, we propose to normalize NIR-RAFI in order to increase the relative contribution of retinal pigment epithelium (RPE) fluorophores. Retinal imaging was performed with a standard protocol holding system parameters invariant in healthy subjects and in patients. Normalized NIR-RAFI was derived by dividing NIR-RAFI signal by NIR reflectance point-by-point after image registration. Regions of RPE atrophy in Stargardt disease, AMD, retinitis pigmentosa, choroideremia, and Leber congenital amaurosis as defined by low signal on SW-RAFI could correspond to a wide range of signal on NIR-RAFI depending on the contribution from the choroidal component. Retinal pigment epithelium atrophy tended to always correspond to high signal on NIR reflectance. Normalizi...
Leber congenital amaurosis (LCA) is a rare hereditary retinal degeneration caused by mutations in... more Leber congenital amaurosis (LCA) is a rare hereditary retinal degeneration caused by mutations in more than a dozen genes. RPE65, one of these mutated genes, is highly expressed in the retinal pigment epithelium where it encodes the retinoid isomerase enzyme essential for the production of chromophore which forms the visual pigment in rod and cone photoreceptors of the retina. Congenital loss of chromophore production due to RPE65-deficiency together with progressive photoreceptor degeneration cause severe and progressive loss of vision. RPE65-associated LCA recently gained recognition outside of specialty ophthalmic circles due to early success achieved by three clinical trials of gene therapy using recombinant adeno-associated virus (AAV) vectors. The trials were built on multitude of basic, pre-clinical and clinical research defining the pathophysiology of the disease in human subjects and animal models, and demonstrating the proof-of-concept of gene (augmentation) therapy. Subst...
Dramatic restoration of retinal function has followed subretinal viral-mediated gene therapy in R... more Dramatic restoration of retinal function has followed subretinal viral-mediated gene therapy in RPE65-deficient animal models of human Leber congenital amaurosis (LCA) caused by RPE65 mutations. Progress in early-phase clinical trials of RPE65-LCA prompted us to begin development of an in vivo bioassay of clinical grade vector stability for later-phase trials. Naturally-occurring Rpe65-mutant rd12 mice (2-4 mo of age) were studied with full-field electroretinograms (ERGs). Flash stimuli (range, -4.1 to 3.6 log scot-cd x s x m(-2)) were used to evoke ERGs in anesthetized, dark-adapted mice. B-wave amplitudes were measured conventionally and luminance-response functions were fit. Leading edges of photoresponses were analyzed with a model of rod phototransduction activation. A unilateral subretinal injection of AAV2-CB(SB)-hRPE65 vector was delivered and therapeutic efficacy of 4 doses spanning a 2 log unit range was studied with ERGs performed about 6 weeks after injection. Uninjected...
We have been engaged in an ongoing study to screen candidate genes for mutations in small familie... more We have been engaged in an ongoing study to screen candidate genes for mutations in small families with various forms of autosomal recessive retinal dystrophy. Here we report the screening of a cohort of 14 families from Sardinia for mutations in the genes encoding the alpha- and beta-subunits of cGMP-phosphodiesterase and RPE65 (PDE6A, PDE6B, and RPE65). Haplotype analysis was performed on each family using simple sequence repeat markers closely flanking or within each of the three gene candidates. For families in which a gene could not be ruled out from segregating with disease, exons of the gene from proband DNAs were screened for mutations by SSCPE (single strand conformation polymorphism electrophoresis). All variants found by SSCPE were sequenced directly. By haplotype analysis, 6/14, 11/14, and 4/13 families were ruled out for PDE6A, PDE6B, and RPE65, respectively. A few variants were found in the proband DNAs of the remaining families, but only one was significant: a 20 bp d...
CONCLUSIONS. These psychophysical results are consistent with histopathologic findings of a selec... more CONCLUSIONS. These psychophysical results are consistent with histopathologic findings of a selec- tive vulnerability for parafoveal rod photoreceptors in AMD. The different patterns of rod and cone system losses among patients at similar clinical stages reinforces the notion that AMD is a group of disorders with underlying heterogeneity of mechanism of visual loss. Dark-adapted macula-wide testing may be a useful
To characterize the disease expression of an autosomal recessive human retinal degeneration assoc... more To characterize the disease expression of an autosomal recessive human retinal degeneration associated with a mutation in TULP1 (tubby-like protein 1), a gene with currently unknown function. Homozygotes and heterozygotes from an extended Dominican kindred with a TULP1 splice-site gene mutation (IVS14+1,G-->A) were studied clinically and with visual function tests. Sequence analysis of TULP1 was also performed in unrelated patients with severe retinal degeneration from a North American clinic population. Homozygotes had nystagmus, visual acuity of 20/200 or worse, color vision disturbances, bull's eye maculopathy, and peripheral pigmentary retinopathy. Younger patients had a relatively wide extent of kinetic visual fields; older patients had only peripheral islands. No rod function was measurable by psychophysics in any of the patients; markedly reduced cone function was detectable across the visual field of younger patients and in the remaining peripheral islands of older pa...
To investigate the transitory plateaux observed during dark adaptation after partial bleaches in ... more To investigate the transitory plateaux observed during dark adaptation after partial bleaches in Sorsby's fundus dystrophy (SFD) and in systemic vitamin A deficiency (VAD). Psychophysical dark adaptation functions were measured after bleaching exposures isomerizing from 2% to 99% of the rhodopsin. Narrow-band stimuli of 1.7 degrees diameter and 200 msec duration were presented at an eccentricity of 30 degrees. After a full bleach, the patients showed typical dark adaptation abnormalities reported for these diseases. The cone recovery was slowed, and the time to the rod-cone break was delayed; the final phase of rod recovery was also slowed but led to a normal final rod threshold. After partial bleaches, short wavelength stimuli produced a biphasic recovery function, with an initial rapid component and plateau, followed by a subsequent break-off and eventual return to prebleach thresholds. Action spectra obtained during the plateaux were consistent with thresholds for shorter wav...
To correlate retinal histopathology with functional changes caused by the rhodopsin Q64ter mutati... more To correlate retinal histopathology with functional changes caused by the rhodopsin Q64ter mutation. A 50-year-old female heterozygote was evaluated clinically and with psychophysical and electroretinographic measurements of rod and cone function. The retinas obtained after death were examined microscopically, including immunolabeling with antibodies against the C- and N-termini of rhodopsin. On clinical examination 4 months before death, patient's acuity was 20/60, and she had midperipheral scotomas with retained function centrally and in the far periphery. The rod electroretinogram (ERG) was undetectable, and the cone ERG was reduced in amplitude with abnormal receptoral and postreceptoral responses. A previous study of the phenotype of mildly affected family members of the donor suggested that the rod outer segments (ROS) were shortened and that only wild-type rhodopsin was functional. The retinas contained only scattered cones in the midperiphery; the maculas and far periphe...
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Papers by Artur Cideciyan