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At least 1,639 records · Page 91Linked to original sources
PubMed2004

X-linked high myopia associated with cone dysfunction.

OBJECTIVE: Bornholm eye disease (BED) consists of X-linked high myopia, high cylinder, optic nerve hypoplasia, reduced electroretinographic flicker with abnormal photopic responses, and deuteranopia. The disease maps to chromosome Xq28 and is the first designated high-grade myopia locus (MYP1). We studied a second family from Minnesota with a similar X-linked phenotype, also of Danish descent. All affected males had protanopia instead of deuteranopia. METHODS: X chromosome genotyping, fine-point mapping, and haplotype analysis of the DNA from 22 Minnesota family individuals (8 affected males and 5 carrier females) and 6 members of the original family with BED were performed. Haplotype comparisons and mutation screening of the red-green cone pigment gene array were performed on DNA from both kindreds. RESULTS: Significant maximum logarithm of odds scores of 3.38 and 3.11 at theta = 0.0 were obtained with polymorphic microsatellite markers DXS8106 and DXYS154, respectively, in the Minnesota family. Haplotype analysis defined an interval of 34.4 cM at chromosome Xq27.3-Xq28. Affected males had a red-green pigment hybrid gene consistent with protanopia. We genotyped Xq27-28 polymorphic markers of the family with BED, and narrowed the critical interval to 6.8 cM. The haplotypes of the affected individuals were different from those of the Minnesota pedigree. Bornholm eye disease-affected individuals showed the presence of a green-red hybrid gene consistent with deuteranopia. CONCLUSIONS: Because of the close geographic origin of the 2 families, we expected affected individuals to have the same haplotype in the vicinity of the same mutation. Mapping studies, however, suggested independent mutations of the same gene. The red-green and green-red hybrid genes are common X-linked color vision defects, and thus are unrelated to the high myopia and other eye abnormalities in these 2 families. CLINICAL RELEVANCE: X-linked high myopia with possible cone dysfunction has been mapped to chromosome Xq28 with intervals of 34.4 and 6.8 centimorgan for 2 families of Danish origin.

Adolescent↗
PubMed1991

Acute idiopathic blind spot enlargement. A spectrum of disease.

The authors present a report on their experience with 10 patients with acute idiopathic blind spot enlargement. All had enlarged steep-margined blind spots without accompanying changes in optic disc appearance, significantly diminished visual acuity or color vision. Fluorescein angiography was obtained in eight patients. Five patients had retinal appearance that was either normal or could not be attributed to a known disease entity. Three patients had the multiple evanescent white dot syndrome, one had acute macular neuroretinopathy, and at least one had presumed ocular histoplasmosis. It has been proposed that acute idiopathic blind spot enlargement is a subset of multiple evanescent white dot syndrome. The authors' findings suggest that multiple evanescent white dot syndrome and other retinal diseases, some not yet identified, are subsets of acute idiopathic blind spot enlargement.

Acute Disease↗
PubMed1999

A locus for autosomal recessive achromatopsia on human chromosome 8q.

Autosomal recessive achromatopsia is a rare disorder characterized by total absent color vision, nystagmus, photophobia, and visual impairment, frequently leading to 'legal blindness'. The primary defect is at the photoreceptor level, with retinal cones being absent or defective. The first locus for this disorder was mapped to chromosome 2q11. Here, we confirm the genetic mapping of a locus discovered in our studies of a kindred with Irish ancestry, but no known consanguinity, in which 5 of 12 children are affected. We have mapped the locus in this disorder in this family to chromosome 8q. Available data now narrow the region containing the putative gene to 1.2 cM.

Adult↗
PubMed2004

Blue cone monochromatism: clinical findings in patients with mutations in the red/green opsin gene cluster.

BACKGROUND: X-linked blue cone monochromatism (BCM) has to be differentiated from x-linked cone dystrophy and autosomal recessive rod monochromatism. METHODS: In nine male patients with congenital cone dysfunction (one family, six single cases; age range: 9-55 years), mutations in the red/green opsin gene cluster were confirmed. Clinical findings were analyzed retrospectively. RESULTS: In one family and three single cases, a single red-green hybrid gene was found carrying a Cys203Arg mutation. Two patients had multiple opsin genes, a red/green hybrid gene and at least one green pigment gene, all carrying the Cys203Arg mutation. In one patient, a large deletion of the locus control region and parts of the red pigment gene were detected. Two patients (ages: 45 and 55 years) complained about progression. Two patients presented with nystagmus. Refractive errors (+8.0 and -11.0 D) and visual acuity were variable (0.05-0.3). Only four patients had a visual acuity > or = 0.1. In two patients, visual acuity could be improved using blue filter glasses. Four of five patients > or = 25 years had dystrophic alterations in the macula. Severe color vision defects and relative central scotoma were present in all patients. In the electroretinogram, residual cone responses were detected in 2/8 patients. CONCLUSIONS: Hybrid red/green opsin genes carrying the Cys203Arg mutation are a frequent cause of BCM in German patients. Molecular genetic evaluation is mandatory for adequate diagnosis of patients since from the clinical data only two patients were diagnosed as having BCM. In the other patients, either rod monochromatism or cone-rod dystrophy could not be excluded with certainty. The patients should be cautioned that macular dystrophy may develop in adults older than 30 years.

Adolescent↗
PubMed1977

A study of X chromosome linkage with field dependence and spatial visualization.

The purposes of this report are to describe a design for the study of X linkage, to illustrate its application using cognitive test scores, and to offer a linkage hypothesis suggested by these data. Sixty-seven three-son families were examined for two X chromosome marker variables--red-green color vision and Xg(a) blood groups--and given a battery of cognitive tests of field dependence and spatial visualization abilities. Evidence was found to suggest that brothers who are identical in Xg(a) phenotype are more similar to each other in extent of field dependence than brothers who are different in Xg(a) phenotype. This result is tentative because of the small number of informative cases and the many linkage associations examined. If cross-validated, such a finding would be consistent with the proposition that an X chromosome gene contributes to the field dependence cognitive style.

Blood Group Antigens↗
PubMed1993

[A comparative study of the detection of abnormal visual pigment genes by PCR and hybridization].

Since color vision abnormalities always involved the exon 5 of visual pigment genes, 2 oligonucleotide primers were designed to amplify the exon 5 of the red and green pigment genes. After electrophoresis of PCR products digested with RsaI or Sau 3A, the DNA fragments from the exon 5 of the red and green pigment genes were separated by virtue of their different restriction endonuclease sites. In the meantime, we analyzed the exon 5 related fragments by Southern blot hybridization with probe from the 3' end of the fourth intron of the visual pigment genes, yielding consistent results. The PCR technique may be of value in prenatal evaluation and genetic counseling.

Base Sequence↗
PubMed1997

Alzheimer-like visual deficits in Down syndrome.

Patients with Alzheimer disease (AD) show visual impairments in color discrimination (blue hues), stereoacuity, and contrast sensitivity. We asked whether the AD-type visual profile occurs in Down syndrome (DS) in light of the fact that AD neuropathology is present in DS by age 40. We tested 22 adults with DS and 18 adults with mental retardation of non-DS etiology (MR). DS subjects made more tritanomalous errors on the test of color vision than predicated by chance (p < 0.05), indicating a deficiency in the discrimination of short wavelengths (blue hues) but not more of other types of hue discrimination errors. DS subjects had higher stereoacuity thresholds than MR subjects (p < 0.01) and reduced contrast sensitivity across the frequency range (p < 0.01). Taken together, the results point to AD-like visual deficits in DS. Like classic AD, DS may be associated with pathological changes in the parastriate and peristriate visual cortex. DS performance was not correlated with age, suggesting that in individual subjects, the AD-like visual deficits may present prior to and independent of age-associated dementia.

Alzheimer Disease↗
PubMed1990

Discrimination of luminance and chromaticity differences by dichromatic and trichromatic monkeys.

Dichromatic and trichromatic representatives from two genera of platyrrhine monkeys that show widespread color vision polymorphism (Saguinus--tamarins, Saimiri--squirrel monkeys) were tested for their abilities to make increment-threshold and flicker discriminations based on luminance and chromaticity differences. The details of these tests were arranged to attempt to emphasize the relative contributions to visual behavior of non-opponent and spectrally-opponent neural mechanisms. The results indicate that dichromatic and trichromatic monkeys differ only trivially on tests where performance is based on the contributions of non-opponent mechanisms, that the contribution of spectrally opponent mechanisms to the "brightness signal" is very similar in trichromatic and dichromatic monkeys, and that in increment-threshold discriminations where there are both chromaticity and luminance cues some test wavelengths yield superior performance for trichromats while others appear to favor the dichromat.

Animals↗
PubMed2004

Progressive cone dystrophy associated with mutation in CNGB3.

PURPOSE: To determine the molecular basis for phenotypic variability in a three-generation consanguineous family containing a single individual with complete achromatopsia and three individuals with progressive cone dystrophy. METHODS: Four affected individuals underwent ophthalmic examination, electrophysiological assessment, color fundus photography, and psychophysical testing. Blood samples were obtained for DNA extraction and mutation screening of the cone-specific cGMP-gated (CNG) channel protein gene CNGB3 was undertaken. RESULTS: The clinical findings in one family member were consistent with a diagnosis of complete achromatopsia, with nystagmus, photophobia, and poor visual acuity from early infancy and complete color-blindness, normal fundi, and absent cone responses with normal rod responses on electroretinography (ERG). Mutation analysis revealed her to be homozygous for the common CNGB3 achromatopsia mutation, 1148delC (Thr383fs). In contrast, the three other symptomatic individuals in the family had findings consistent with progressive cone dystrophy. Their visual problems began later in childhood (ranging from 3 to 14 years of age) and there was evidence of progressive deterioration in cone function. All three had a marked tritanopic color vision defect and fundoscopy revealed bilateral macular atrophy. Electrophysiological testing of these three subjects demonstrated clear evidence of progressive deterioration of cone responses over time; rod responses were normal. All three individuals with this progressive phenotype were found to be compound heterozygotes for the 1148delC (Thr383fs) frameshift mutation and a novel Arg403Gln missense mutation in CNGB3. CONCLUSIONS: Mutations in CNGB3, which have been shown to cause achromatopsia, are now shown to be associated with autosomal recessive progressive cone dystrophy. In this study, a novel Arg403Gln mutation was identified, located in the middle of the pore domain of the cone CNG cation channel beta-subunit, which when associated with the nonsense mutation Thr383fs, resulted in progressive cone dystrophy.

Adult↗
PubMed2004

[Effect of an early visual encoding defect on attentional function: a study of daltonism using the Stroop test].

The Stroop color-word test is often used to assess attentional function. In this study we investigated whether dyschromatopsia affects the results of this test, and in that case which are the attentional consequences of this color-vision trouble. Event-related potentials were recorded on 19 dyschromatopsic subjects when submitted to a video-displayed Stroop test, and compared to those of 19 control subjects. Results showed that reaction times of dyschromatopsic subjects, although generally longer than those of controls, had normal interference and facilitation effects. Potentials evoked by neutral stimulations were delayed for P2 and P3 waves, and those evoked by word-containing stimulations showed delays for N2b (N320) and P3 waves. The premotor potential appeared modified in dyschromatopsic patients, whereas error negativities, or correct response negativities were identical to those of control subjects. We conclude that dyschromatopsia affects negatively the performance in the Stroop test, at sensory levels which are reflected by evoked potentials, but without important consequences on attentional function. In particular, dyschromatopsia did not alter significantly the attentional focusing on the chromatic aspects of the stimulus.

Adult↗
PubMed1989

Molecular genetics of human blue cone monochromacy.

Blue cone monochromacy is a rare X-linked disorder of color vision characterized by the absence of both red and green cone sensitivities. In 12 of 12 families carrying this trait, alterations are observed in the red and green visual pigment gene cluster. The alterations fall into two classes. One class arose from the wild type by a two-step pathway consisting of unequal homologous recombination and point mutation. The second class arose by nonhomologous deletion of genomic DNA adjacent to the red and green pigment gene cluster. These deletions define a 579-base pair region that is located 4 kilobases upstream of the red pigment gene and 43 kilobases upstream of the nearest green pigment gene; this 579-base pair region is essential for the activity of both pigment genes.

Adolescent↗
PubMed2001

Autosomal dominant cone and cone-rod dystrophy with mutations in the guanylate cyclase activator 1A gene-encoding guanylate cyclase activating protein-1.

OBJECTIVE: To describe the phenotype in 3 families with dominantly inherited cone and cone-rod dystrophy with mutations in guanylate cyclase activator 1A (GUCA1A), the gene-encoding guanylate cyclase activator protein-1 (GCAP-1). METHODS: Phenotypic characterization with psychophysical and electrophysiological evaluation and confocal laser scanning ophthalmoscopy was performed in 2 families with a Tyr99Cys mutation and 1 family with a Pro50Leu mutation. Haplotype analysis was performed in the families with Tyr99Cys mutation. RESULTS: The families with a Y99C mutation were shown to be ancestrally related. Decreased visual acuity and loss of color vision occurred after the age of 20 years, followed by progressive atrophy of the central 5 degrees to 10 degrees. Electrophysiological testing revealed generalized loss of cone function, with preservation of rod function. Abnormal rod and cone sensitivities were confined to the central 5 degrees to 10 degrees. Confocal laser scanning ophthalmoscopy imaging showed abnormalities of autofluorescence in early disease. Subjects with a Pro50Leu mutation demonstrated marked variability in expressivity from minimal abnormalities of macular function to cone-rod dystrophy. CONCLUSIONS: The phenotype associated with the Y99C mutation in GUCA1A is distinctive, with little variation in expression. By contrast, that associated with the P50L mutation demonstrates variable expressivity. CLINICAL RELEVANCE: Phenotype-genotype correlation in these 2 mutations demonstrates 2 different phenotypes.

Adolescent↗
PubMed1989

[Important progress for the ophthalmologist in basic genetic research].

Ophthalmologists and human geneticists share a long standing interest in hereditary diseases and anomalies of the eye. Many of the primary genetic eye diseases are known, as ophthalmic symptoms are frequently part of a pleiotropic gene effect or the eye is affected secondarily. Progress in human genetics has also improved the understanding of genetic eye diseases. This can be demonstrated in the analysis of the function of color-vision genes and their abnormalities as well as the retinoblastoma gene. A line can be drawn from early formal analysis of pedigrees to cytogenetic mapping and, finally DNA analysis and sequencing of the involved genes. These advances have not only led to theoretical insights but also have practical applications where the determination of risk is concerned or prenatal diagnosis, genetic counselling, preventive measures and guidance. The retinoblastoma gene has become an important model for a tumor suppressor gene and tumorigenesis in general. Its influence on other types of tumors, such as osteosarcoma and breast cancer must be clarified. Sequencing of the gene opens the possibility of reconstructing the primary gene product by "reverse genetics" and of analyzing its mode of action. DNA analysis has been extended to an increasing number of eye diseases. Precise clinical and genetic analysis and diagnosis are of primary importance, however, for progress in this field.

Chromosome Aberrations↗
PubMed1980

Tokyo Medical College Test in acquired dyschromatopsia.

In order to find a successor for the Hardy, Rand and Rittler (AOH-R-R) test the author made a comparison between the AOH-R-R and the Tokyo Medical College (TMC) tests in acquired dyschromatopsia. The diagnosis of the TMC type of a red-green defect is often in contradiction with the results of other color vision tests. In grading the severity of a red-green defect the TMC classification is shifted with regard to the AOH-R-R classification. A corrected grading in better agreement with the AOH-R-R classification is proposed. The TMC blue-yellow screening plates are more sensitive than the AOH-R-R blue-yellow screening plates. A TMC (supermild) blue-yellow defect in general corresponds to blue-yellow defects detected by FM 100 Hue and its derivatives. In the study of acquired dyschromatopsia, it is necessary to use a test battery. In our opinion the TMC can be used in such a test battery although it is not a real successor to the AOH-R-R. If ever the AOH-R-R is reprinted, the blue-yellow plates should be extended to a 'supermild' degree as are the TMC blue-yellow plates.

Adult↗
PubMed2001

Cumulative exposure to styrene and visual functions.

BACKGROUND: Results from a 1990-1992 longitudinal study of several reinforced plastics plants showed that for those workers whose styrene exposure had decreased, color vision (CV) improved; while near visual contrast sensitivity (CS) was poorer. METHODS: In 1999, we retested these visual functions in 18 workers with good visual acuity. A cumulative exposure index (CEI), corrected for respirator use, was calculated for each worker. RESULTS: Intra-individual comparison of mandelic acid (MA) showed a significant decrease over time (Friedman; P = 0.015), but current values were not related to CEI. For CV, no significant difference was observed between 1992 and 1999; present results were not related to MA or CEI. The CS profile decreased over time, with significant differences at 3 cpd (Friedman; P < 0.05). CS did not vary with MA levels, but was significantly depressed at the intermediate frequencies among those in the upper CEIH category (Kruskal-Wallis; P < 0.05). CONCLUSIONS: These findings suggest that CS loss increases with long-term cumulative exposure, reflecting chronic damage to the neuro-optic pathways.

Adult↗
PubMed1991

Clinical and electroretinographic comparison between Aland Island eye disease and a newly found related disease with X-chromosomal inheritance.

Two subjects representing AIED (Aland Island Eye Disease) and a family with 5 males affected with an AIED related X-linked hereditary eye disease were studied clinically and electrophysiologically. The clinical picture of AIED includes myopia and astigmatism, reduced visual acuity, nystagmus, ocular albinism, hemeralopia and dyschromatopsia (No. 300600, McKusick 1990). The subjects with the related disease showed astigmatism with or without myopia, reduced visual acuity, slight hemeralopia, normal color vision in 3/5 subjects, no ocular albinism and nystagmus only in one case. In both diseases the ERG was abnormal showing defective a- and b-waves, but there were also differences. The most notable was the greater reduction of the b-wave amplitude in the mixed (rod and cone) responses for the white stimulus in the ERG of the AIED related disease. With regard to the pathogenesis we propose that in both diseases rod and cone functions are defective but in an AIED related disease a defective cone function inhibits the transmission of the rod signals to the rod bipolars, causing greatly reduced mixed responses. The clinical and ERG findings of this study suggest that the 5 subjects of our family do not represent AIED but another X-linked hereditary eye disease. The investigation to find out the gene locus of this disease is going on.

Adolescent↗
PubMed1986

Visual and auditory neurotoxicity in patients receiving subcutaneous deferoxamine infusions.

Of 89 patients receiving nightly subcutaneous deferoxamine for transfusion-dependent thalassemia major or Diamond-Blackfan anemia, 13 presented with visual loss or deafness of acute onset or both. Detailed ophthalmologic, audiologic, and evoked-potential studies uncovered abnormalities caused by neurotoxicity in 27 more. Four patients with visual loss had optic neuropathy, with a marked decrease in acuity, loss of color vision, and delayed visual evoked potentials. Five asymptomatic patients had changes in the pigment of the retinal epithelium. The hearing loss was characterized by a high-frequency sensorineural deficit, which necessitated hearing aids in six patients. When deferoxamine was stopped, recovery of vision was complete in 2 patients and partial in 2, and in 22 patients with abnormal audiograms, reversal of the hearing deficit was complete in 4 and partial in 1. An analysis of the clinical data showed that members of the affected group were younger, had lower serum ferritin values, and were self-administering higher doses of deferoxamine per kilogram of body weight. Significantly lower doses of deferoxamine were being taken by patients without abnormalities than by those with visual symptoms, abnormal audiograms, or prolonged evoked potentials (P less than 0.001, less than 0.006, and less than 0.04, respectively). The data implicate high-dose deferoxamine as a central factor in the pathogenesis of the neurotoxicity. We strongly recommend careful regulation of the deferoxamine dosage and serial audiovisual monitoring in all patients receiving the drug.

Adolescent↗
PubMed1983

Color plates to help identify patients with blue cone monochromatism.

A new color vision test distinguishes patients with X-chromosome-linked blue cone monochromatism from those with autosomal recessive rod monochromatism. The test consists of two instructional and four test plates. Each test plate has three identical blue-green arrows and one purple-blue arrow; test plates differ from one another only with respect to the chroma of the purple-blue arrow. All five patients with blue cone monochromatism, aged 5 to 31 years, easily distinguished the purple-blue arrow on all four test plates, whereas none of the seven patients with rod monochromatism, aged 6 to 60 years, could distinguish the purple-blue arrow on all four plates. If a boy has a reduced visual acuity, normal rod electroretinograms, and 30-Hz cone electroretinograms reduced more than 97% below normal, this test can be used to determine whether his condition is an X-chromosome-linked one or an autosomal recessive one.

Adolescent↗