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PubMed1994

Genetic linkage of cone-rod retinal dystrophy to chromosome 19q and evidence for segregation distortion.

Inherited retinal dystrophies are the most common cause of childhood blindness in the developed world. Cone-rod retinal dystrophies are severe examples of this group of disorders. Analysis of a large cone-rod dystrophy pedigree suggested that inheritance within the family was influenced by meiotic drive (p = 0.008), a rare segregation distortion in human genetics. Two-point linkage analysis showed significant linkage with three markers mapping to chromosome 19q. Multipoint analysis gave a maximum lod score of 10.08 (theta = 0.05) distal to D19S47. Cone-rod dystrophy is therefore assigned to 19q13.1-q13.2 and a new candidate locus for other retinal dystrophies is identified.

Child↗

PubMed1992

Juvenile atrophy of pigment epithelium and choriocapillaris.

Two brothers, 20 and 21 years of age, are reported who had a circumscribed area of atrophy of the pigment epithelium, choriocapillaris and part of the choroidal vessels in the posterior pole; they were otherwise in good health. In addition, the optic discs, particularly in the older brother had hypoplastic characteristics. Both patients were known to have had low visual acuity and nystagmus since early childhood. Electro-oculography was normal. Electroretinography and color vision tests were subnormal in both patients. Although the morphological picture showed features similar to central areolar choroidal dystrophy, familial bilateral macular colobomata, serpiginous choroiditis and some cases of cone dystrophy, there are clinical and electrophysiological reasons for differentiating the cases presented here from these other diseases.

Adult↗

PubMed1990

Cone dysfunction in a subgroup of patients with autosomal dominant cerebellar ataxia.

Four patients with autosomal dominant cerebellar ataxia and retinal degeneration underwent neurologic and ophthalmologic examinations and computer-assessed corneal electroretinography. Previous reports described progressive panretinal degeneration initially involving the cones and subsequently spreading to the rods. By contrast, all our patients displayed evidence of selective dysfunction of the cone system in one or two successive electroretinograms, irrespective of their age or duration of visual symptoms. Color vision testing, funduscopy, and fluorescein angiography suggested a cone dystrophy. Within the period of observation only one patient showed progression of cone dysfunction. In patients with hereditary ataxias, quantitative electroretinography provides an objective and sometimes early indication of retinal degeneration and helps to characterize it.

Adult↗

PubMed1987

Nerve fibre layer loss in diseases of the outer retinal layer.

We present examples of nerve fibre layer changes in diseases thought to affect primarily the outer retinal layers. These disease processes include cone-rod dystrophies, rod-cone dystrophies, juvenile macular degeneration (Stargardt's disease) and fundus flavimaculatis, vitelliform macular dystrophy, and Leber's congenital amaurosis. All were associated with alterations in the retinal nerve fibre layer, either diffuse or focal. The presence of these nerve fibre layer changes raises the question of transsynaptic degeneration and of possible primary or associated disease of other retinal cells than the receptors-namely, bipolar, amacrine, Mueller, or ganglion cells--in these disease of the outer retinal layer. Involvement of the nerve fibre layer also indicates the need to examine patients with defects in the nerve fibre layer by electroretinograms and other tests for outer retinal layer disease when no obvious optic nerve disease is present.

Adult↗

PubMed1996

[Hereditary retinal diseases].

Hereditary retinal dystrophies can be subdivised into central (macular) and peripheral degenerations. Stargardt disease, Best disease, cone dystrophy and retinoschisis, affecting children or young adults, are the 4 commonest macular dystrophies. Retinitis pigmentosa, with primary affects photoreceptors, presents a wide clinical, genetic and molecular heterogeneity. It is certainly the most representative cause of peripheral degeneration. Recent advances in molecular biology allow a more complete clinical definition of these inheritable retinal diseases.

Adolescent↗

PubMed2000

An unusual central retinal dystrophy associated with ichthyosis vulgaris.

A number of ichthyosis syndromes may have retinal abnormalities such as the retinitis pigmentosa-like diffuse rod-cone dystrophy in Refsum's syndrome and the maculopathy in Sjögren-Larsson syndrome. We present two sisters who have an unusual, almost identical, bilaterally symmetric central retinal dystrophy associated with ichthyosis vulgaris in the absence of other systemic disorders. We believe that this dystrophy has not been previously described in patients with any of the known varieties of ichthyosis.

Adolescent↗

PubMed1999

[Electroretinogram and electrooculogram in retinal degeneration].

Electroretinogram (ERG) and electrooculogram (EOG) are fundamental for proper early diagnosis of retinal dystrophies and degenerations. The most characteristic changes of ERG and EOG in such retinal dystrophies as Stargardt's disease, Best's disease, fundus flavimaculatus, fundus albipunctatus, retinitis pigmentosa, choroideremia, iuvenile retinoschisis, congenital stationary night blindness, progressive cone dystrophy and in some of retinal degenerations for differential diagnosis were described. Electrophysiological state of retina in retinal dystrophy depends on patient's age and pattern of inheritance. Very often typical for dystrophy changes in ERG and EOG without any visible pathology on eye fundi are found. On the other hand there are some of degenerations similar to dystrophies in clinical examination. In such cases only ERG and EOG allow to be sure which diagnosis should be done.

Electrooculography↗

PubMed1978

Classification of the diffuse chorioretinal heredodystrophies or peripheral tapetoretinal dystrophies.

The best classification of the diffuse chorioretinal heredodystrophies (predominantly peripheral tapetoretinal dystrophies) is that which is based on the mode of heredity. Thus, it is possible to distinguish the autosomal recessive forms (Leber's disease, pigmentary retinopathy, Bietti's crystalline fundus dystrophy, albipunctate retinopathy, choroidal atrophy and gyrate atrophy of the chorioid and retina), the autosomal dominant forms (certain forms of pigmentary retinopathy, choroidal atrophy, progressive cone dystrophy and Sorsby's pseudo-inflammatory dystrophy), and the sex-lined forms, whether recessive (pigmentary retinopathy), dominant (pigmentary retinopathy) or intermediate (pigmentary retinopathy and choroideraemia).

Genes, Recessive↗

PubMed2005

Congenital retinal dystrophy and corneal opacity in trisomy 8 mosaicism.

Trisomy 8 mosaicism can present with a wide variety of systemic and ophthalmologic manifestations. We report a patient with an extinguished electroretinogram and diffuse retinal pigment epithelial abnormalities suggestive of a rod-cone dystrophy, which has not been previously reported in association with trisomy 8. A finding that has been described in several patients with trisomy 8 is a central corneal opacity, but there are no data regarding the natural history of this finding; the corneal opacity in our patient spontaneously improved. This case expands the clinical spectrum of this rare entity.

Chromosomes, Human, Pair 8↗

PubMed2005

[Genetics of retinitis pigmentosa: metabolic classification and phenotype/genotype correlations].

Retinitis pigmentosa (RP, prevalence 1/4000) is a set of hereditary retinal dystrophies characterized by pigment deposits in fundus and progressive death of photoreceptors, always associated with the alteration of retinal pigment epithelium. Genetic heterogeneity of the typical nonsyndromic form (rod cone dystrophy) is extensive: 11 genes and one locus were reported for autosomal dominant RP, 17 genes and five loci for autosomal recessive RP, and two genes and two loci for X-linked RP. A survey of mutation screening reports in large series of patients indicates that the frequency of mutations for all cloned genes varies from 40% to 54% of cases in autosomal dominant RP, from 17% to 24% in autosomal recessive RP (excluding the USH2A gene for which the values remain uncertain) and from 61% to 89% in X-linked RP. Very few studies report on sporadic cases except for the two X-linked genes, RP2 and RPGR, which account for 29% of sporadic cases in males. Altogether, the two most frequently involved genes are RPGR (13% of all RP cases) and RHO (4%), an important consideration for molecular diagnosis. Finally, we roughly estimate that currently known genes do not represent more than 50% of RP cases, suggesting that many genes remain to be discovered. The known genes can be classified into metabolic groups according to the encoded protein: visual transduction, visual cycle, transcription factors, structural proteins, spliceosome complex and cellular traffic, indicating the high level of specialization of photoreceptors and of the retinal pigment epithelium. In parallel with this classification, genotype/phenotype correlations have been established that will help ophthalmologists to suspect particular genes, and thereby mechanisms. This approach will provide better informations to patients and will orient the choice of future therapies.

Genotype↗

PubMed1987

Characteristic ERG-flicker anomaly in incomplete congenital stationary night blindness.

Ten patients with the incomplete type of congenital stationary night blindness (CSNB) were examined with a 30 Hz flicker electroretinogram (ERG). After 30 min of dark adaptation, 30 Hz flicker ERG was recorded continuously for 12-15 min under white background illumination. All patients showed an exaggerated increase of amplitude and a universal characteristic change of wave shape as the light adaptation progressed. Thirty normal subjects also showed increased amplitude during light adaptation, but the increase in amplitude was significantly less than in incomplete-type CSNB, and there was little change in wave shape. The same procedure was applied to patients with complete-type CSNB, retinitis pigmentosa, congenital retinoschisis, cone dystrophy, and Oguchi's disease; neither the exaggerated increase of amplitude nor the wave change was seen. Our results indicate that incomplete-type CSNB is a newly identified cone-rod dysfunction syndrome with a special functional property.

Electroretinography↗

PubMed2003

ERGs, cone-isolating VEPs and analytical techniques in children with cone dysfunction syndromes.

Photoreceptor and post-receptoral function in children with congenital and acquired cone disorders was measured by full-field electroretinogram (ERG) and transient visual evoked potentials (VEPs). Subjects were five rod monochromats (RM), five with cone dystrophy (CD), and 30 controls. Patients were diagnosed by clinical findings, ERGs, and standard color vision tests. VEP stimuli were check reversals and color grating onsets that stimulated each photoreceptor type (L-, M-, or S-cones) or post-receptoral pathways (L-M, white/black). VEP signal-to-noise ratios (S/N) were calculated by Fourier analysis of VEP epochs. All RM patients showed extinguished cone ERGs. A near normal S-cone VEP was recorded from a blue-cone rod monochromat without any signal from the L- or M-cone stimuli. Two other RM patients were classified as incomplete RM based on a low-level VEP signal from either L- or M-cone stimuli. CD patients had mildly to severely reduced ERGs and VEPs were abnormal to all cone-isolating stimuli. The VEP S/N ratio was not significantly correlated with the amount of rod contrast in the color stimuli. Color VEPs provide an objective assessment of macular cone function in children with cone dysfunction syndromes that is more sensitive to residual central cone function than standard full-field ERGs. VEP techniques may be useful in the early detection of cone loss in children, especially in children who do not tolerate ERG testing.

Adolescent↗

PubMed2004

Guanylate cyclase-activating proteins: structure, function, and diversity.

The guanylate cyclase-activating proteins (GCAPs), Ca2+-binding proteins of the calmodulin gene superfamily, function as regulators of photoreceptor guanylate cyclases. In contrast to calmodulin, which is active in the Ca2+-bound form, GCAPs stimulate GCs in the [Ca2+]-free form and inhibit GCs upon Ca2+ binding. In vertebrate retinas, at least two GCAP1 and two GCs are present, a third GCAP3 is expressed in humans and fish, and at least five additional GCAP4-8 genes have been identified or are predicted in zebrafish and pufferfish. Missense mutations in GCAP1 (Y99C, I143NT, E155G, and P50L) have been associated with autosomal dominant cone dystrophy. Absence of GCAP1/2 in mice delays recovery of the photoresponse, a phenotype consistent with delay in cGMP synthesis. In the absence of GCAP2, GCAP1 supports the generation of wild-type flash responses in both rod and cone cells. Recent progress revealed an unexpected complexity of the GC-GCAP system, pointing, out a number of unsolved questions.

Amino Acid Sequence↗

PubMed2001

Retinal dystrophies caused by mutations in RPE65: assessment of visual functions.

AIMS: To characterise the disease in patients with mutations in RPE65. METHODS: Individuals from two families were studied clinically. RESULTS: 13 and 20 year old compound heterozygote individuals from one family with R234X and 1121delA mutations showed nystagmus, macular dystrophy and low contrasted spots in the fundus. Some heterozygotes had macular drusen. A 40 year old compound heterozygote individual from another family with L22P and H68Y mutations had few bone spicule pigment deposits and macular atrophy. CONCLUSION: Compound heterozygote individuals had severe rod-cone dystrophies featuring few pigment deposits in the fundus, pigment epithelium atrophy, and early involvement of the macula, with variations in severity leading to the diagnosis of Leber's congenital amaurosis or retinitis pigmentosa. Macular drusen in heterozygotes carrying a null allele may reflect the decreased capacity in the RPE65 function.

Adolescent↗

PubMed2002

Species-specific subcellular localization of RPGR and RPGRIP isoforms: implications for the phenotypic variability of congenital retinopathies among species.

The retinitis pigmentosa GTPase regulator (RPGR) is encoded by the X-linked RP3 locus, which upon genetic lesions leads to neurodegeneration of photoreceptors and blindness. The findings that RPGR specifically and directly interacts in vivo and in vitro with retina-specific RPGR-interacting protein 1 (RPGRIP) and that human mutations in RPGR uncouple its interaction with RPGRIP provided the first clue for the retina-specific pathogenesis of X-linked RP3. Recently, mutations in RPGRIP were found to lead to the retinal dystrophy, Leber congenital amaurosis. However, mouse models null for RPGR had, surprisingly, a very mild phenotype compared with those observed in XlRP3-affected humans and dogs. Moreover, recent reports are seemingly in disagreement on the localization of RPGR and RPGRIP in photoreceptors. These discrepancies were compounded with the finding of RPGR mutations leading exclusively to X-linked cone dystrophy. To resolve these discrepancies and to gain further insight into the pathology associated with RPGR- and RPGRIP-allied retinopathies, we now show, using several isoform-specific antibodies, that RPGR and RPGRIP isoforms are distributed and co-localized at restricted foci throughout the outer segments of human and bovine, but not mice rod photoreceptors. In humans, they also localize in cone outer segments. RPGRIP is also expressed in other neurons such as amacrine cells. Thus, the data lend support to the existence of species-specific subcellular processes governing the function and/or organization of the photoreceptor outer segment as reflected by the species-specific localization of RPGR and RPGRIP protein isoforms in this compartment, and provide a rationale for the disparity of phenotypes among species and in the human.

Amino Acid Sequence↗

PubMed1998

Visual function and gene analysis in a family with Oguchi's disease.

A family with 1 case of retinitis pigmentosa (III-1) and 2 cases of Oguchi's disease (III-2, 3) was examined in terms of electrophysiology as well as molecular biology. The proband (III-3), a 42-year-old female, and 2 older brothers (III-1, 2, aged 52 and 45 years) and 2 unaffected members in the same family participated in this study. Corrected visual acuities of the individuals with Oguchi's disease (III-2, 3) were 1.2. On funduscopy, blood vessels stood out in relief against a metallic-appearing background and a Mizuo-Nakamura phenomenon was evident. Full-field electroretinograms (ERGs) recorded from the proband were indicative of rod dystrophy, but results of other electrophysiological examinations (multifocal ERG, pattern ERG and visual-evoked cortical potential recordings) were within normal limits. Patient III-1 had corrected visual acuities of RE 20 cm/m.m. and LE 30 cm/n.d., severe chorioretinal atrophy in both fundi, and full-field ERG revealed rod-cone dystrophy. Mutation of the arrestin gene (1147de1A) was detected in all 3 patients. Visual function in each patient coincides with that of retinitis pigmentosa or Oguchi's disease, respectively.

Adult↗

PubMed1997

["Oligocone" trichromasy, a rare form of incomplete achromatopsia].

PATIENTS AND METHODS: An 11-year-old girl presented because of reduced visual acuity while color vision was almost normal. Besides a general ophthalmological examination, special psychophysical tests, such as perimetry, color vision tests using pseudoisochromatic plates, arrangement tests, the Nagel anomaloscope and spectral sensitivity measurement, and electrophysiological tests (electroretinogram and electrooculogram) were conducted. RESULTS: The tests yielded the following: congenital nystagm, normal results at ophthalmoscopy, best visual acuity of 0.1 monocular and 0.2 binocular. Perimetry revealed a relatively central scotoma. All color vision tests showed only mild dysfunction of the blue-sensitive cones. Findings at photopic electroretinogram were almost completely lacking. There was no sign of progression in the last 6 years. CONCLUSION: Differential diagnosis includes all diseases associated with congenital nystagm, such as aniridia, diseases of the optic nerve, albinism and all forms of hereditary cone dysfunction, cone dystrophies and complete and incomplete congenital stationary monochromatism. In the present case the findings are most congruent with oligocone trichromasy.

Child↗

PubMed2005

Cone opsin mislocalization in Rpe65-/- mice: a defect that can be corrected by 11-cis retinal.

PURPOSE: In retinal degenerative diseases, rod photoreceptors typically deteriorate more rapidly than cone photoreceptors. In the Rpe65(-/-) mouse, a model for Leber's congenital amaurosis, cones degenerate much more rapidly than rods. In this model, the retinoid processing pathway in the retinal pigment epithelium is disrupted, and 11-cis retinal is not generated. This study was designed to investigate the feasibility of restoring functional cones with exogenous 11-cis retinal. METHODS: Rpe65(-/-)::Rho(-/-) mice were used to remove any interference of rods and compared with wild-type (wt) mice. Pups were injected intraperitoneally with 11-cis retinal, starting at postnatal day (P)10, and were maintained in complete darkness. At P25, cone function was assessed with photopic single-flash and flicker ERGs. Cone survival was determined immunohistochemically with cone-specific antibodies, and cone opsin levels were obtained by quantitative RT-PCR. RESULTS: At P25, cone density and transcript levels of cone opsins were drastically reduced, but a minute cone electroretinogram was detected, indicating that the cones were functional. Confocal microscopy revealed that the cone opsins were mislocalized, suggesting that their transport to the outer segments was impaired. Intraperitoneal administrations of 11-cis retinal before P25 led to increased transport of cone opsins to the outer segments and preserved cones anatomically and functionally. CONCLUSIONS: The results suggest that the ligand is required during cone opsin synthesis for successful opsin trafficking and that without 11-cis retinal, cones may degenerate because of opsin mislocalization. These results may have important consequences for the treatment of cone dystrophies.

Animals↗