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At least 829 records · Page 46Linked to original sources
PubMed2003

Posterior ocular malformations in children: somatic, neuroradiological and cognitive aspects.

AIM: To investigate associated neurological, endocrinological and cognitive dysfunctions in children with visual impairment caused by optic nerve hypoplasia or optic nerve/fundus coloboma and/or microphthalmus. METHODS: Forty children born between 1990 and 1998 were assessed by neurological examination, re-evaluation of neuroradiological investigations, review of medical records and examination of cognitive levels. RESULTS: Neurological dysfunctions (epilepsy and/or motor impairment) were found in 13/28 children with optic nerve hypoplasia and in 3/12 children with coloboma/microphthalmus. The optic pathways were thin in 22/24, an abnormal posterior pituitary gland and/or thin infundibulum was found in 16/22 and absence of septum pellucidum in 14/27 children with optic nerve hypoplasia. Other types of cerebral abnormalities occurred in 9/26 children. Among children with coloboma/microphthalmus, the optic pathways were thin in 4/8 children but none had pituitary or cerebral midline abnormalities. Sixteen children with optic nerve hypoplasia were receiving hormone substitution but none of the children with coloboma/microphthalmus. Thirteen of the 16 children with optic nerve hypoplasia and with an abnormal pituitary region had endocrinological deficiencies. Mental retardation was found in 9/24 of the children with optic nerve hypoplasia and in 5/10 of the children with coloboma/microphthalmus. CONCLUSION: Endocrinological. neurological and neuroradiological defects seem more common in children with optic nerve hypoplasia than in children with coloboma. A pituitary region that appears abnormal in magnetic resonance imaging seems to predict endocrinological deficits in children with optic nerve hypoplasia.

Blindness↗
PubMed1996

Influence of gestational age at exposure on the prenatal effects of gamma-radiation.

The abdominal region of pregnant Swiss albino mice was exposed to single dose of 0.5 Gy gamma-radiation at gestation days from 1.5 to 17.5 days post-coitus (p.c). The animals were sacrificed on day 18 p.c. and foetuses were examined for resorption and embryonic death, foetal death, growth retardation, small head, low brain weight, micro-phthalmia and any other gross morphological abnormalities. The period of maximum sensitivity for each effect varied. The only demonstrable effect of irradiation during the pre-implantation period was an increase in prenatal mortality. Resorptions were maximal after exposure between days 2 and 4 p.c. The pre-implantation irradiated embryos which survived did not show any major foetal abnormalities. These results confirm earlier mouse studies using higher doses of X-rays. Small head, low brain weight and microphthalmia were prominent after exposure during the late organogenesis period, especially between days 9 and 13 p.c. But no other externally visible anomalies were detected. These findings demonstrate that mouse organogenesis is very sensitive to radiation-induced retardation of development, even at doses < 1 Gy. One exencephaly, one cleft palate and two cases of open eyelids were observed in the foetuses exposed on days 14.5 and 15.5 p.c.; the number of these cases was too small to indicate a causal relationship with exposure.

Abnormalities, Radiation-Induced↗
PubMed2005

Unilateral isolated microphthalmia inherited as an autosomal recessive trait.

PURPOSE: To report a family with unilateral isolated microphthalmia showing an autosomal recessive pattern of inheritance. CASE REPORT: We report a family in which three out of four children, one male and monozygotic female twins, were born with unilateral isolated microphthalmia to healthy consanguineous parents. One twin additionally had a horseshoe kidney. Rare cases of familial isolated microphthalmia/anophthalmia have been previously described. This is the first report of a family with autosomal recessive isolated microphthalmia occurring unilaterally in all affected individuals. It remains unknown how this inherited genetic disease results in unilateral manifestation. CONCLUSION: Mirror imaging of this condition in the monozygotic twins may help elucidate the underlying mechanism. The constellation of features in this family may contribute to solve remaining questions of research into symmetry and asymmetry.

Abnormalities, Multiple↗
PubMed2005

Hereditary high hypermetropia in the Faroe Islands.

PURPOSE: To characterize the phenotype of two families with high hypermetropia from the Faroe Islands. METHODS: Ophthalmologic evaluation including ultrasound oculometry and anthropometric measurements. RESULTS: Of the 40 examined family members, 15 individuals (8 males, 7 females; ages: 6-77 years; mean: 36.5 years) had small deep-set eyes with high hypermetropia (median: + 16.5 D; range: + 7.75 to + 22), short axial eye length (< 21 mm), and a thickened eye wall. The median corrected visual acuity was 0.4 (0.2-0.9). Ocular complications included angle-closure glaucoma in six eyes, uveal effusion in three eyes, cataract in two eyes, and esotropia with amblyopia in three eyes. An emergency case of uveal effusion and retinal detachment after Yag iridotomy eventually responded to systemic corticosteroids and scleral resection surgery with a slow visual recovery. No associated ocular or systemic malformations were found in the series. In addition to the two examined families, six smaller Faroese families with high hypermetropia are briefly reported. CONCLUSIONS: The study highlights the signs and symptoms of a rare hereditary phenotype characterized by a short axial length mainly confined to the posterior segment of the eye, a shallow anterior chamber, and a thickened eye wall. The morphological characteristics predispose for sight-threatening complications such as angle-closure glaucoma, chorioretinal pathology including uveal effusion, and amblyopia. Regular ophthalmic follow-up is therefore of obvious importance in families known to have small eyes/high hypermetropia. An endemic high prevalence in the Faroe Islands suggests the presence of a founder effect, and further genetic research would probably indicate pseudodominant rather than dominant transmission

Adolescent↗
PubMed2005

Multiple congenital malformations including severe eye anomalies and abnormal cerebellar development with Dandy-Walker malformation in a girl with partial trisomy 3q.

PURPOSE: Ocular anomalies have been associated with numerous chromosomal abnormalities. This report describes partial trisomy 3q in a two-month-old girl with dysmorphic features of the Dup3q phenotype and severe eye and cerebellar malformations. METHODS: Clinical examination and chromosomal analysis were conducted. RESULTS: The karyotype of the propositus was 46,XX, ins(3)(pter --> p25::q27 --> q21::p25 --> qter). She had an abnormal head shape, low-set malformed ears, coarse facies, short webbed neck, abnormal foot position, polycystic kidney, and spina bifida. There was also bilateral microphthalmia that was more severe on the right side, microcornea, and corneal opacity. She had posterior fossa abnormalities, including cerebellar vermis hypoplasia suggestive of a Dandy-Walker (DW) malformation. CONCLUSIONS: This girl with an intrachromosomal duplication of distal 3q and typical phenotype belongs to the severe end of the spectrum for such cases. The ocular manifestations of the 3q duplication syndrome provide additional evidence of the involvement of developmental eye genes in this chromosomal segment.

Cerebellum↗
PubMed2006

Optic disc coloboma and localized chorioretinal defects in constitutional partial trisomy 8 mosaicism.

Constitutional partial trisomy 8 mosaicism is a rare chromosomal multisystem disorder with systemic and ophthalmologic manifestations. We report the case of a 15-year-old female mosaic for trisomy 8 who has unilateral colobomatous microphthalmia and multiple chorioretinal defects. These congenital anomalies have not been previously reported in association with constitutional partial trisomy 8 mosaicism.

Adolescent↗
PubMed2006

Ophthalmic manifestations of Sanjad-Sakati syndrome.

BACKGROUND: Sanjad-Sakati syndrome (SSS) is a rare disorder characterized by hypoparathyroidism, growth and developmental delay, and dysmorphism. The purpose of this report is to describe the ophthalmic manifestations of Sanjad-Sakati syndrome (SSS; hypoparathyroidism-mental retardation-dysmorphism syndrome, HRD) (OMIM 241410). PATIENTS: We included a total of 17 patients who were seen at two hospitals in Riyadh. METHODS: Each patient underwent a complete ophthalmologic evaluation including visual acuity assessment, orthoptic workup, slit-lamp biomicroscopy, intraocular pressure measurement, cycloplegic retinoscopy, funduscopy, corneal diameter, and axial length measurement. RESULTS: All 17 (100%) of the patients had normal visual acuity. All patients had microphthalmia with normal intraocular pressure. Eight (47%) of the patients had esotropia and four (23%) had exotropia. Ophthalmoscopy revealed tortuous retinal blood vessels in all patients. Hyperopic astigmatism was present in 16 (94%) patients. CONCLUSION: Patients with SSS display a variety of ocular findings including errors of refraction, strabismus, and retinal vascular tortuousity.

Adolescent↗
PubMed2006

Ependymal tissue in microphthalmia with cyst.

PURPOSE: To report the nature of the contents of a cyst associated with microphthalmia and optic nerve coloboma in a male infant. DESIGN: Clinicopathologic report. CASE REPORT: A male infant in good general health presented with a massively swollen, protruded left lower eyelid since birth. The globe was not identifiable. MRI disclosed a microphthalmic globe in the upper nasal orbit and an orbital cystic mass consisting of various compartments. Examination of the fellow eye showed a large optic nerve coloboma. As the protrusion of the left lower eyelid was progressive, aspiration of the cyst was performed twice. Finally, the cyst was removed surgically due to repeated filling. RESULTS: Examination of the aspirated fluid showed resemblance to cerebrospinal fluid (CSF). During surgery, the cyst was not found to communicate with the cerebrospinal fluid system. However, tissue resembling choroidal plexus lined the wall of the cyst that was adherent to the optic nerve. Histological evaluation of the tissue revealed ependymal cells. DISCUSSION: The presence of CSF in microphthalmic cysts does not necessarily imply a connection to the CNS, but may be due to local CSF production by ectopic ependymal cells.

Coloboma↗
PubMed1998

Targeted ablation of connexin50 in mice results in microphthalmia and zonular pulverulent cataracts.

In the ocular lens, gap junctional communication is a key component of homeostatic mechanisms preventing cataract formation. Gap junctions in rodent lens fibers contain two known intercellular channel-forming proteins, connexin50 (Cx50) and Cx46. Since targeted ablation of Cx46 has been shown to cause senile-type nuclear opacities, it appears that Cx50 alone cannot meet homeostatic requirements. To determine if lens pathology arises from a reduction in levels of communication or the loss of a connexin-specific function, we have generated mice with a targeted deletion of the Cx50 gene. Cx50-null mice exhibited microphthalmia and nuclear cataracts. At postnatal day 14 (P14), Cx50-knockout eyes weighed 32% less than controls, whereas lens mass was reduced by 46%. Cx50-knockout lenses also developed zonular pulverulent cataracts, and lens abnormalities were detected by P7. Deletion of Cx50 did not alter the amounts or distributions of Cx46 or Cx43, a component of lens epithelial junctions. In addition, intercellular passage of tracers revealed the persistence of communication between all cell types in the Cx50-knockout lens. These results demonstrate that Cx50 is required not only for maintenance of lens transparency but also for normal eye growth. Furthermore, these data indicate that unique functional properties of both Cx46 and Cx50 are required for proper lens development.

Animals↗
PubMed1998

Age-resolving osteopetrosis: a rat model implicating microphthalmia and the related transcription factor TFE3.

Microphthalmia (Mi) is a basic helix-loop-helix-leucine zipper (b-HLH-ZIP) transcription factor implicated in pigmentation, mast cells, and bone development. Two dominant-negative mi alleles (mi/mi and Mior/Mior) in mice cause osteopetrosis. In contrast, osteopetrosis has not been observed in a number of recessive mi alleles, suggesting the existence of Mi protein partners important in osteoclast function. An osteopetrotic rat of unknown genetic defect (mib) has been described whose skeletal sclerosis improves dramatically with age and that is associated with pigmentation defects reminiscent of mouse mi alleles. Here we report that this rat strain harbors a large genomic deletion encompassing the 3' half of mi including most of the b-HLH-ZIP region. Osteoclasts from these animals lack Mi protein in contrast to wild-type rat, mouse, and human osteoclasts. Mi is not detectable in primary osteoblasts. In addition TFE3, a b-HLH-ZIP transcription factor related to Mi, was found to be expressed in osteoclasts, but not osteoblasts, and to coimmunoprecipitate with Mi. These results demonstrate the existence of members of a family of biochemically related transcription factors that may cooperate to play a central role in osteoclast function and possibly in age-related osteoclast homeostasis.

Animals↗
PubMed1998

A locus for autosomal recessive congenital microphthalmia maps to chromosome 14q32.

Congenital microphthalmia (CMIC) (OMIM 309700) may occur in isolation or in association with a variety of systemic malformations. Isolated CMIC may be inherited as an autosomal dominant, an autosomal recessive, or an X-linked trait. On the basis of a whole-genome linkage analysis, we have mapped the first locus for isolated CMIC, in a five-generation consanguineous family with autosomal recessive inheritance, to chromosome 14q32. All affected individuals in this family have bilateral CMIC. Linkage analysis gave a maximum two-point LOD score of 3.55 for the marker D14S65. Surrounding this marker is a region of homozygosity of 7.3 cM, between the markers D14S987 and D14S267, within which the disease gene is predicted to lie. The genes for several eye-specific transcription factors are located on human chromosome 14q and in the syntenic region of mouse chromosome 12. However, both CHX10 (14q24.3), mutations of which give rise to CMIC in mouse models, and OTX2 (14q21-22) can be excluded as candidates for autosomal recessive congenital microphthalmia (arCMIC), since they map outside the critical disease region defined by recombination events. This suggests that arCMIC is caused by defects in a novel developmental gene that may be important or even essential in eye development.

Animals↗
PubMed2000

A locus for autosomal dominant colobomatous microphthalmia maps to chromosome 15q12-q15.

Congenital microphthalmia is a common developmental ocular disorder characterized by shortened axial length. Isolated microphthalmia is clinically and genetically heterogeneous and may be inherited in an autosomal dominant, autosomal recessive, or X-linked manner. Here, we studied a five-generation family of Sephardic Jewish origin that included 38 members, of whom 7 have either unilateral or bilateral microphthalmia of variable severity inherited as an autosomal dominant trait with incomplete penetrance. After exclusion of several candidate loci, we performed a genome-scan study and demonstrated linkage to chromosome 15q12-q15. Positive LOD scores were obtained with a maximum at the D15S1007 locus (maximum LOD score 3.77, at recombination fraction 0.00). Haplotype analyses supported the location of the disease-causing gene in a 13.8-cM interval between loci D15S1002 and D15S1040.

Adolescent↗
PubMed2006

CRYBA4, a novel human cataract gene, is also involved in microphthalmia.

Genetic analysis of a large Indian family with an autosomal dominant cataract phenotype allowed us to identify a novel cataract gene, CRYBA4. After a genomewide screen, linkage analysis identified a maximum LOD score of 3.20 (recombination fraction [theta] 0.001) with marker D22S1167 of the beta -crystallin gene cluster on chromosome 22. To date, CRYBA4 was the only gene in this cluster not associated with either human or murine cataracts. A pathogenic mutation was identified in exon 4 that segregated with the disease status. The c.317T-->C sequence change is predicted to replace the highly conserved hydrophobic amino acid phenylalanine94 with the hydrophilic amino acid serine. Modeling suggests that this substitution would significantly reduce the intrinsic stability of the crystalline monomer, which would impair its ability to form the association modes critical for lens transparency. Considering that CRYBA4 associates with CRYBB2 and that the latter protein has been implicated in microphthalmia, mutational analysis of CRYBA4 was performed in 32 patients affected with microphthalmia (small eye). We identified a c.242T-->C (Leu69Pro) sequence change in exon 4 in one patient, which is predicted here to disrupt the beta -sheet structure in CRYBA4. Protein folding would consequently be impaired, most probably leading to a structure with reduced stability in the mutant. This is the first report linking mutations in CRYBA4 to cataractogenesis and microphthalmia.

Adult↗
PubMed2006

Mutations of the mitochondrial holocytochrome c-type synthase in X-linked dominant microphthalmia with linear skin defects syndrome.

The microphthalmia with linear skin defects syndrome (MLS, or MIDAS) is an X-linked dominant male-lethal disorder almost invariably associated with segmental monosomy of the Xp22 region. In two female patients, from two families, with MLS and a normal karyotype, we identified heterozygous de novo point mutations--a missense mutation (p.R217C) and a nonsense mutation (p.R197X)--in the HCCS gene. HCCS encodes the mitochondrial holocytochrome c-type synthase that functions as heme lyase by covalently adding the prosthetic heme group to both apocytochrome c and c(1). We investigated a third family, displaying phenotypic variability, in which the mother and two of her daughters carry an 8.6-kb submicroscopic deletion encompassing part of the HCCS gene. Functional analysis demonstrates that both mutant proteins (R217C and Delta 197-268) were unable to complement a Saccharomyces cerevisiae mutant deficient for the HCCS orthologue Cyc3p, in contrast to wild-type HCCS. Moreover, ectopically expressed HCCS wild-type and the R217C mutant protein are targeted to mitochondria in CHO-K1 cells, whereas the C-terminal-truncated Delta 197-268 mutant failed to be sorted to mitochondria. Cytochrome c, the final product of holocytochrome c-type synthase activity, is implicated in both oxidative phosphorylation (OXPHOS) and apoptosis. We hypothesize that the inability of HCCS-deficient cells to undergo cytochrome c-mediated apoptosis may push cell death toward necrosis that gives rise to severe deterioration of the affected tissues. In summary, we suggest that disturbance of both OXPHOS and the balance between apoptosis and necrosis, as well as the X-inactivation pattern, may contribute to the variable phenotype observed in patients with MLS.

Amino Acid Sequence↗
PubMed2002

Loss of holocytochrome c-type synthetase causes the male lethality of X-linked dominant microphthalmia with linear skin defects (MLS) syndrome.

Girls with MLS syndrome have microphthalmia with linear skin defects of face and neck, sclerocornea, corpus callosum agenesis and other brain anomalies. This X-linked dominant, male-lethal condition is associated with heterozygous deletions of a critical region in Xp22.31, from the 5' untranslated region of MID1 at the telomeric boundary to the ARHGAP6 gene at the centromeric boundary. HCCS, encoding human holocytochrome c-type synthetase, is the only gene located entirely inside the critical region. Because single gene analysis is not feasible in MLS patients (all have deletions), we generated a deletion of the equivalent region in the mouse to study the molecular basis of this syndrome. This deletion inactivates mouse Hccs, whose homologs in lower organisms (cytochrome c or c1 heme lyases) are essential for function of cytochrome c or c1 in the mitochondrial respiratory chain. Ubiquitous deletions generated in vivo lead to lethality of hemizygous, homozygous and heterozygous embryos early in development. This lethality is rescued by expression of the human HCCS gene from a transgenic BAC, resulting in viable homozygous, heterozygous and hemizygous deleted mice with no apparent phenotype. In the presence of the HCCS transgene, the deletion is easily transmitted to subsequent generations. We did obtain a single heterozygous deleted female that does not express human HCCS, which is analogous to the low prevalence of the heterozygous MLS deletion in humans. Through the study of these genetically engineered mice we demonstrate that loss of HCCS causes the male lethality of MLS syndrome.

5' Untranslated Regions↗
PubMed2002

A Gja8 (Cx50) point mutation causes an alteration of alpha 3 connexin (Cx46) in semi-dominant cataracts of Lop10 mice.

Mutations of connexin alpha 8 (GJA8 or Cx50) and connexin alpha 3 (GJA3 or Cx46) in humans have been reported to cause cataracts with semi-dominant inheritance patterns. Targeted null mutations in Gja8 and Gja3 in mice cause cataracts with recessive inheritance. The molecular bases for these differences in inheritance patterns and the mechanism for cataractogenesis in these mutants are poorly understood. We recently mapped an autosomal semi-dominant cataract [lens opacity 10 (Lop10)] mutation to mouse chromosome 3 and identified a missense mutation (G-->C) in the Gja8 gene, which causes glycine at codon 22 to be replaced with arginine (G22R). Moreover, we demonstrated that the alpha 8 G22R isoform is a loss-of-function mutant for alpha 8, as well as a dominant mutation for reducing the phosphorylated forms of alpha 3 connexin in vivo. To test the hypothesis that the alteration of endogenous alpha 3 connexin in Lop10 mice led to a unique lens phenotype, we generated double mutant offspring between Lop10 and the Gja3(tm1) (alpha 3(-/-)) mice. The double homozygous mutant mice (Lop10/Lop10 alpha 3(-/-)) showed relatively normal lens cortical fibers compared to the Lop10 mice. A functional impairment of endogenous alpha 3 connexin is therefore partly responsible for cellular phenotypes in the Lop10 mice. This study has provided some novel molecular insights into mouse and human cataractogenesis caused by alpha 8 and alpha 3 mutations. These mouse models will be useful for investigating the mechanistic relationship between gap junction impairment and cataract formation.

Amino Acid Substitution↗
PubMed1993

The genes for X-linked ocular albinism (OA1) and microphthalmia with linear skin defects (MLS): cloning and characterization of the critical regions.

We have used cell lines from patients with deletions and translocations involving the Xp22 region to map the genes for two X-linked disorders, ocular albinism type 1 (OA1) and microphthalmia with linear skin defects (MLS). Using existing and newly isolated DNA markers, the map position within Xp22 of key patient breakpoints, defining the boundaries of the genomic regions involved in these disorders (the critical regions), has been precisely determined. A 2.6 Mb yeast artificial chromosome (YAC) contig, spanning the critical regions for these two disorders, was assembled. Detailed long-range restriction analysis of the contig established the sizes of the critical regions to be 200 kb for OA1 and 800 - 925 kb for MLS. Ten potential CpG-islands, representing candidate sites for genes, have been mapped within the 2.6 Mb region. Our data should greatly facilitate efforts aimed at cloning the genes for these developmental defects.

Albinism, Ocular↗