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At least 991 records · Page 55Linked to original sources
PubMed1980

Ocular abnormalities of true microcephaly.

'True' microcephaly is associated with extremely varied ocular abnormalities, the most frequent being squint and optic atrophy. Within the heterogeneous group of the microcephalies it seems we can isolate a syndrome consisting of microcephaly, mental retardation, chorioretinal dysplasia and sometimes microphthalmia and embryological remnants such as persistence of the primary vitreous or persistence of its minor forms. Genetic transmission of such anomalies is generally considered to be autosomal recessive. The cases we are reporting on suggest that in some cases dominant transmission can be incriminated.

Adult↗
PubMed1992

High hyperopia with papillomacular fold.

We report a case of evolutive high hyperopia in a child aged 10 years. It is associated with organic amblyopia due to a large papillomacular retinal fold. Ultrasonography and CT scan helped to establish the diagnosis. This is probably a hereditary disease affecting the development of the posterior sclera.

Child↗
PubMed2003

Microphthalmia resulting from MSX2-induced apoptosis in the optic vesicle.

PURPOSE: Microphthalmia is a relatively common ocular malformation. Molecular mechanisms that lead to this dire condition are largely unknown. Msx genes have been shown to be expressed in the developing eye. In the Msx1;Msx2, double mutant mouse, eye development arrests early in embryogenesis. To investigate possible functions of Msx2 in early ocular development, we created transgenic animals that overexpress Msx2. METHODS: Msx2 transgenic embryos and nontransgenic littermates were examined histopathologically. The effect of Msx2 overexpression on retinal cell proliferation was assayed by bromodeoxyuridine (BrdU) incorporation and immunohistochemical staining. Apoptosis was determined by TUNEL labeling. Expression of retina and retinal pigmented epithelium (RPE)-specific genes was investigated by performing in situ hybridization or immunohistochemical staining. RESULTS: Forced expression of the Msx2 gene resulted in optic nerve aplasia and microphthalmia in all transgenic animals. In developing retinas of Msx2 transgenic animals, proliferation was significantly reduced and increased numbers of retinal cells underwent apoptosis. Marker analysis showed suppression of Bmp4 and induction of Bmp7 gene expression in the optic vesicle. Ectopic concurrent expression of the RPE cell markers Cx43 and Trp-2 in the neural retinal layer suggests cell fate respecification. CONCLUSION: These results indicate that forced expression of Msx2 perturbs BMP signaling in the developing eye and is accompanied by an increase in retinal cell death and a reduction in cell proliferation. Thus, deregulated Msx2 gene expression may be a plausible genetic mechanism by which the autosomal dominant form of congenital microphthalmia may arise.

Animals↗
PubMed2003

Corneal abnormalities in Pax6+/- small eye mice mimic human aniridia-related keratopathy.

PURPOSE: To investigate corneal abnormalities in heterozygous Pax6(+/Sey-Neu) (Pax6(+/-), small eye) mice and compare them with aniridia-related keratopathy in PAX6(+/-) patients. METHODS: Fetal and postnatal corneal histopathology, adult corneal thickness, and the distribution of K12-immunostained cells were compared in wild-type and Pax6(+/-) mice. RESULTS: Prenatally, the corneal epithelium was thinner in Pax6(+/-) fetuses than wild-type littermates, but the stroma appeared irregular, hypercellular, and thickened. The anterior chamber angle was obliterated, and the iris was hypoplastic from early developmental stages. The adult Pax6(+/-) corneal epithelium was thinner, had fewer layers, and included goblet cells, indicating repopulation from conjunctival epithelium. The ocular surface was often roughened, with epithelial vacuolation and lens tissue within the stroma. The corneal stroma was thicker centrally, with an irregular lamellar alignment. Many adult Pax6(+/-) corneas were vascularized or contained cellular infiltrates, but some remained clear. Corneal degeneration was age-related: Older Pax6(+/-) mice had prominent subepithelial pannus and more goblet cells in the peripheral corneal epithelium. Cytokeratin 12 stained very weakly in the peripheral and superficial corneal epithelium in 12-month-old Pax6(+/-) mice. CONCLUSIONS: Corneal abnormalities in Pax6(+/-) mice are similar to those in aniridia-related keratopathy in PAX6(+/-) patients. This extends the relevance of this mouse model of human aniridia to include corneal abnormalities. Incursion of goblet cells suggests impaired function of Pax6(+/-) limbal stem cells, abnormal expression of cytokeratin 12 may result in greater epithelial fragility, and corneal opacities in older mice may reflect poor wound-healing responses to accumulated environmental insults.

Animals↗
PubMed2003

Genetic background influences cataractogenesis, but not lens growth deficiency, in Cx50-knockout mice.

PURPOSE: Deletion of connexin (Cx)50 produces microphthalmia with nuclear cataracts. To determine whether these two traits are influenced by genetic background and are dependent on each other, mice carrying the Cx50 deletion in two different strains were generated, and the growth defect and severity of cataracts were analyzed. METHODS: Cx50-knockout mice were generated in the 129S6 strain, and back-crossed into the C57BL/6J genetic background. To analyze the influence of genetic background on the observed phenotype, postnatal lens growth, lens clarity, lens histology and crystallin solubility were determined and compared between the two strains of Cx50-knockout mice. RESULTS: The growth deficiency persisted, regardless of genetic background, but genetic modifiers that differentially altered the solubility of crystallin proteins influenced the severity of cataracts. Expression levels of Cx46 were similar in all animals, regardless of genetic background, indicating that the differences were not due to a compensatory upregulation of Cx46. CONCLUSIONS: Taken together, these data indicate that the two components of the Cx50 phenotype are independent of each other and that cataractogenesis is under the influence of an unidentified genetic modifier.

Animals↗
PubMed2004

Catalase and peroxiredoxin 5 protect Xenopus embryos against alcohol-induced ocular anomalies.

PURPOSE: To study the molecular mechanisms underlying alcohol-induced ocular anomalies in Xenopus embryos. METHODS: Xenopus embryos were exposed to various concentrations (0.1%-0.5%) of alcohol, and the subsequent effects in eye development and in eye marker gene expression were determined. To investigate the role of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in fetal alcohol syndrome (FAS)-associated ocular injury, two antioxidant enzymes, catalase and peroxiredoxin 5, were overexpressed in the two blastomeres of the two-cell stage Xenopus embryos. RESULTS: Exposure of Xenopus embryos to alcohol during eye development produced marked gross ocular anomalies, including microphthalmia, incomplete closure of the choroid fissure, and malformation of the retina in 40% of the eyes examined. In parallel, alcohol (0.1%-0.5%) dose dependently and significantly reduced the expression of several eye marker genes, of which TBX5, VAX2, and Pax6 were the most vulnerable. Overexpression of catalase and of cytosolic and mitochondrial peroxiredoxin 5 restored the expression of these alcohol-sensitive eye markers and significantly decreased the frequency of ocular malformation from 39% to 21%, 19%, and 13% respectively. All these enzymes reduced alcohol-induced ROS production, but only peroxiredoxin 5 inhibited RNS formation in the alcohol-treated embryos. CONCLUSIONS: The results suggest that oxidative and nitrosative stresses both contribute to alcohol-induced fetal ocular injury.

Abnormalities, Drug-Induced↗
PubMed2004

Mutations of VMD2 splicing regulators cause nanophthalmos and autosomal dominant vitreoretinochoroidopathy (ADVIRC).

PURPOSE: To investigate the genetic basis of autosomal dominant vitreoretinochoroidopathy (ADVIRC), a rare, inherited retinal dystrophy that may be associated with defects of ocular development, including nanophthalmos. METHODS: A combination of linkage analysis and DNA sequencing in five families was used to identify disease-causing mutations in VMD2. The effect of these mutations on splicing was assessed using a minigene system. RESULTS: Three pathogenic sequence alterations in VMD2 were identified in five families with nanophthalmos associated with ADVIRC. All sequences showed simultaneous missense substitutions and exon skipping. CONCLUSIONS: VMD2 encodes bestrophin, a transmembrane protein located at the basolateral membrane of the RPE, that is also mutated in Best macular dystrophy. We support that each heterozygous affected individual produces three bestrophin isoforms consisting of the wild type and two abnormal forms: one containing a missense substitution and the other an in-frame deletion. The data showed that VMD2 mutations caused defects of ocular patterning, supporting the hypothesized role for the RPE, and specifically VMD2, in the normal growth and development of the eye.

Bestrophins↗
PubMed2004

Absence of SIX6 mutations in microphthalmia, anophthalmia, and coloboma.

PURPOSE: To investigate whether 173 patients with microphthalmia, anophthalmia, and coloboma have mutations in the eye-development gene SIX6. METHODS: The two exons of the SIX6 gene were amplified by PCR from patients' genomic DNA and directly sequenced to search for mutations. The PCR products of 75 patients were also analyzed by denaturing high-performance liquid chromatography (DHPLC). RESULTS: Six SIX6 polymorphisms were identified in the patient panel. Three of these polymorphisms change the encoded amino acid. However, all six polymorphisms were also identified in unaffected individuals. There was no statistically significant difference in genotypes between patients and control subjects. CONCLUSIONS: No evidence was found that SIX6 mutations underlie human congenital structural eye malformations.

Adult↗
PubMed2005

Three novel Pax6 alleles in the mouse leading to the same small-eye phenotype caused by different consequences at target promoters.

PURPOSE: To characterize three new mouse small-eye mutants detected during ethylnitrosourea mutagenesis programs. METHODS: Three new mouse small-eye mutants were morphologically characterized, particularly by in situ hybridization. The mutations were mapped, and the candidate gene was sequenced. The relative amount of Pax6-specific mRNA was determined by real-time PCR. Reporter gene analysis used Crygf and Six3 promoter fragments in front of a luciferase gene and HEK293 cells as recipients. RESULTS: The new mutations--ADD4802, Aey11, and Aey18--were mapped to chromosome 2; causative mutations have been characterized in Pax6 (Aey11: C-->T substitution in exon 8, creating a stop codon just in front of the homeobox; ADD4802: G-->A substitution at the beginning of intron 8 changes splicing and leads to an altered open reading frame and then to a premature stop codon; Aey18: G-->A exchange in the last base of intron 5a leads also to a splice defect, skipping exons 5a and 6). Real-time PCR indicated nonsense-mediated decay in Pax6Aey11 and Pax6Aey18 mutants but not in Pax6ADD4802. This result is supported by the functional analysis of corresponding expression constructs in cell culture, where the Aey11 and Aey18 alleles did not show a stimulation of the Six3 promotor or an inhibition of the Crygf promoter (as wild-type constructs do). However, the Pax6ADD4802 allele stimulated both promoters. CONCLUSIONS: Together with functional analysis in a reporter gene assay and immunohistochemistry using Pax6 antibodies, it is suggested that the Pax6Aey11 and Pax6Aey18 alleles act through a loss of function, whereas ADD4802 represents a gain-of-function allele.

Alleles↗
PubMed2006

Heterozygous and homozygous mutations in PITX3 in a large Lebanese family with posterior polar cataracts and neurodevelopmental abnormalities.

PURPOSE: The PITX3 gene, which codes for a homeobox bicoidlike transcription factor is responsible for dominant cataract and anterior segment mesenchymal dysgenesis in humans. In the current study, a family with autosomal dominant posterior polar cataract (PPC) and a PITX3 mutation that cosegregates with the disease was examined. Also studied were two siblings who were homozygous for the PITX3 mutation who had microphthalmia and significant neurologic impairment. METHODS: A genome-wide screen, linkage analysis in the PITX3 chromosomal region 10q25, haplotype analysis, and sequencing of the PITX3 gene were performed on 28 affected and 14 unaffected member of a three-generation Lebanese family. RESULTS: Genome-wide linkage analysis showed a lod score of 3.56 at theta = 0.00 on chromosome 10 at area q25. Analysis of the haplotypes and phenotypes confined the disease locus to a region on 10q25 between the markers D10S1239 and D10S1268. A candidate gene, PITX3, maps to that region. Sequencing of the PITX3 gene revealed a heterozygous G deletion mutation in 25 of the 42 family members. In addition, two siblings from a consanguineous marriage were found to be homozygous for the deletion. CONCLUSIONS: This is the first report of homozygous PITX3 mutations in humans. The phenotype in these individuals highlights the role of PITX3 in ocular and central nervous system (CNS) development.

Cataract↗
PubMed2006

Ocular abnormalities in mice lacking the Ski proto-oncogene.

PURPOSE: Persistent hyperplastic primary vitreous (PHPV) is a developmental ocular malformation often associated with additional ocular abnormalities. This study involved a novel mouse model of PHPV, generated by a null mutation of the Ski proto-oncogene, that displays other anterior segment and retinal malformations often found in human cases of PHPV. METHODS: Morphologic and histologic analyses of Ski-/- mice were used to document ocular abnormalities in comparison to those of normal littermates. Immunohistochemical studies were used to examine the expression of relevant markers of ocular and vascular development including Pax6, beta-III tubulin, and Flk1. RESULTS: PHPV and microphthalmia were found in 100% of Ski-/- fetuses. Other abnormalities included anterior segment and lens dysgenesis, retinal folds, chorioretinal coloboma, and Peters anomaly. The severity was variable, even in a highly homogeneous genetic background. PHPV was characterized by the presence of retrolental fibrous and vascular tissue that did not express the neuronal marker beta-III tubulin, but was positive for Flk1 expression and contained no obviously pigmented cells. CONCLUSIONS: The results show that normal ocular development requires the function of the Ski proto-oncogene, and mice lacking Ski have many features associated with PHPV, and some similarities with Peters anomaly in humans. Defects in Ski-/- mice closely resemble those described in animals lacking several of the retinoic acid receptor genes, or in animals exposed to excess retinoic acid during gestation. Ski has been shown to repress transcription induced by retinoic acid signaling, and may thus affect ocular development by regulating RA signaling.

Abnormalities, Multiple↗
PubMed1981

Ocular manifestations of the fetal hydantoin syndrome.

Eleven per cent of infants exposed to hydantoins in utero have a recognizable pattern of abnormalities with serious clinical consequences. This report of a child born to a mother taking diphenylhydantoin emphasized the ocular findings. At birth and subsequent 8-month exam, a girl was noted to have microphthalmus, prominent iris vessels, and an inferior iris and choroidal colobma. Relation of these anomalies to teratogenic properties of diphenylhydantoin is discussed.

Coloboma↗