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PubMed1990

[Orbital reconstruction].

Orbital reconstruction by local flaps, distant flaps, free skin transplants or mucosal transplants, means numerous operations. Good results are often spoiled by postoperative shrinking, especially, when the patient previously had radiation. Therefore we use nowadays free flaps (forearm flap, dorsalis pedis flap) as fascio-cutaneous or fascio-mucosal flaps. By this procedure, reconstruction can be done in one or two stages and postoperative shrinking can be avoided. Our experience in 4 cases is demonstrated.

Adolescent↗

PubMed2005

Dissecting the genetic complexity of human 6p deletion syndromes by using a region-specific, phenotype-driven mouse screen.

Monosomy of the human chromosome 6p terminal region results in a variety of congenital malformations that include brain, craniofacial, and organogenesis abnormalities. To examine the genetic basis of these phenotypes, we have carried out an unbiased functional analysis of the syntenic region of the mouse genome (proximal Mmu13). A genetic screen for recessive mutations in this region recovered thirteen lines with phenotypes relevant to a variety of clinical conditions. These include two loci that cause holoprosencephaly, two that underlie anophthalmia, one of which also contributes to other craniofacial abnormalities such as microcephaly, agnathia, and palatogenesis defects, and one locus responsible for developmental heart and kidney defects. Analysis of heterozygous carriers of these mutations shows that a high proportion of these loci manifest with behavioral activity and sensorimotor deficits in the heterozygous state. This finding argues for the systematic, reciprocal phenotypic assessment of dominant and recessive mouse mutants. In addition to providing a resource of single gene mutants that model 6p-associated disorders, the work reveals unsuspected genetic complexity at this region. In particular, many of the phenotypes associated with 6p deletions can be elicited by mutation in one of a number of genes. This finding implies that phenotypes associated with contiguous gene deletion syndromes can result not only from dosage sensitivity of one gene in the region but also from the combined effect of monosomy for multiple genes that function within the same biological process.

Animals↗

PubMed1981

Ontophyletics of the nervous system: eyeless mutants illustrate how ontogenetic buffer mechanisms channel evolution.

Genetics and molecular biology have shown the mechanisms that allow the genome to provide both the continuity and the variation from generation to generation within a phylogeny. Embryology and developmental biology show the mechanisms that turn the genome into an organism. Mutations, the basis for evolutionary change, cannot in themselves ensure concordance between their products and the products of unchanged genes. Thus, mutations will not necessarily produce a viable organism. On the other hand, ontogenetic buffer mechanisms normally maintain concordance in the developing organism. In addition, ontogenetic buffer mechanisms can integrate discordant mutations into viable organisms that can then be perpetuated during evolution. The evolutionary role of one ontogenetic buffer mechanism, compensatory innervation, is well illustrated in the anopthalmic mutant mouse. In the anopthalmic mouse, a single gene mutation removes afferent axons of the dorsal lateral geniculate nucleus, and compensatory innervation by another population of axons ensures that the dorsal lateral geniculate remains integrated into the central nervous system. Within each organism's ontogeny is a hierarchy of sources of compensatory innervation, and this hierarchy will determine how any particular deafferentating mutation will be buffered. In this way, an ontogeny can channel the phylogeny of which it is a member.

Animals↗

PubMed1982

The primary ultrastructural defect caused by anophthalmic white (Wh) in the Syrian hamster.

Anophthalmic white (Wh) of the Syrian hamster is a highly pleiotropic dominant spotting color mutation causing homozygotes to be deaf, blind, and white. An ultrastructural analysis of embryonic tissue reveals that Wh causes the retention of cilia by cells of opposing layers of the embryonic retina and by the lens fiber cells. Previous ultrastructural analyses indicate that Wh also causes the retention of cilia by secretory cells of the anterior lobe of adult pituitaries. We propose that the primary ultrastructural defects caused by Wh is the retention of cilia by embryonic cells. These retained cilia are hypothesized to interfere with normal cell-cell interactions and subsequent cell differentiation.

Animals↗

PubMed2026

Socket motility assessment of anophthalmic sockets: a systematic review.

PURPOSE: Systematically review and categorize the methods used to assess socket and prosthetic motility in anophthalmic patients following enucleation or evisceration. METHODS: A systematic review was conducted in accordance with PRISMA guidelines. PubMed, Embase, Web of Science, and Scopus were searched from inception through September 2024. Studies reporting qualitative or quantitative assessments of motility in anophthalmic sockets or ocular prostheses were included. Motility assessment methods were categorized as qualitative (descriptive or graded clinical evaluation) or quantitative (numerical measurements in millimeters, degrees, or objective tracking systems). RESULTS: Thirty-five studies encompassing 1,819 patients met inclusion criteria. Nineteen studies used qualitative assessment methods, including subjective observation, graded scales based on cardinal gaze positions, or comparison with the contralateral eye. Sixteen studies employed quantitative techniques, such as the Kestenbaum limbus test, Lister perimeter measurements, conjunctival or limbal markings, photographic image analysis, infrared eye-tracking systems, and magnetic search-coil technology. Considerable heterogeneity was observed in measurement techniques, reporting standards, timing of assessment, and distinction between socket and prosthetic motility. CONCLUSIONS: Substantial variability exists in the methods used to assess motility in anophthalmic sockets, limiting comparability across studies. Establishing standardized, feasible, and reproducible assessment approaches may improve outcome reporting and facilitate meaningful comparisons in future oculoplastic research.

Humans↗

PubMed2006

Amniotic membrane transplantation versus mucous membrane grafting in anophthalmic contracted socket.

PURPOSE: Amniotic membrane has been successfully used for treatment of various ocular surface disorders, but there have been no published reports untill now regarding its use in the treatment of contracted socket. The aim of this study was to determine the role of amniotic membrane and to compare the results with mucous membrane grafting in anophthalmic contracted socket. METHODS: A prospective study of 20 eyes with mild to moderate anophthalmic contracted socket was carried out. Two groups, each with 10 eyes, were formed randomly. Group A underwent amniotic membrane transplantation, and Group B mucous membrane grafting. Prosthesis was fitted 6-8 weeks post operatively. The volume and fornices' length was compared preoperatively and at 3, 6 and 12 months postoperatively. RESULTS: Apart from measurements, patient satisfaction was an important criteria in defining the success of the procedure. At the end of 12 months, the relative increase between the 2 groups in the fornix and volume measurements were statistically significant (SF-0.001,IF-0.001,V-0.001) with better patient comfort in group A. There was no statistical significance regarding the rate of complications between both the groups (p = 0.29). CONCLUSION: Amniotic membrane emerges as a viable alternative to established mucous membrane grafting as it causes less patient morbidity, faster recovery and better fitting of prosthesis. No contracture is observed with amniotic membrane as against mucous membrane. It is cheap and easily available and has no significant complications associated with it.

Adolescent↗

PubMed1987

Dose-incidence relationships for exencephalia, anophthalmia and prenatal mortality in mouse embryos irradiated with fission neutrons or 250 kV X-rays.

Groups of pregnant mice were irradiated at selected times between 10.00 hours on gestation day 7 and 16.00 hours on day 8. Each group received 0.39 Gy of neutrons or 1.60 Gy of X-rays, or was sham irradiated. We identified a period of high susceptibility of the embryos to radiation-induced exencephalia, anophthalmia and prenatal mortality early in gestation day 8. Dose-incidence relationships in this period were investigated with 0.19-0.48 Gy of neutrons and with 0.40-2.00 Gy of X-rays. With increasing neutron dose, incidence of exencephalia in live embryos rose and then declined. This response suggests that embryos with neutron injury of the type that leads to exencephalia are at a greater risk of dying in utero than are similarly irradiated embryos not so injured, and that this risk increases with dose. A model is proposed that accounts for the shape of the neutron dose-incidence curve. X-ray-induced exencephalia showed only an increase with dose. In X-irradiated litters, almost invariably, the incidence of anophthalmia was higher in exencephalic than in nonexencephalic embryos and the ratio of these incidences (relative risk) decreased toward 1 with increasing dose. A model is proposed that accounts for these observations. The incidence of bilateral anophthalmia in X-irradiated embryos was higher than would be expected if the bilateral form resulted solely from independent injury at each of two equally susceptible sites.

Abnormalities, Radiation-Induced↗

PubMed2004

Congenital anophthalmia: a circadian rhythm study.

A circadian rhythm of heart rate and respiratory rate was seen at 1, 8, and 12 months of age in an infant born without ocular tissue, which supports the possibility that the time cues were nonphotic. No melatonin circadian rhythm was detected at any age up to 9 years of age, and this is most likely associated with the anophthalmia and lack of photic input to the suprachiasmatic nucleus. Usually circadian organization is present after the neonatal period and approaches adult levels with development.

Adult↗

PubMed2005

Heterozygous mutations of OTX2 cause severe ocular malformations.

Major malformations of the human eye, including microphthalmia and anophthalmia, are examples of phenotypes that recur in families yet often show no clear Mendelian inheritance pattern. Defining loci by mapping is therefore rarely feasible. Using a candidate-gene approach, we have identified heterozygous coding-region changes in the homeobox gene OTX2 in eight families with ocular malformations. The expression pattern of OTX2 in human embryos is consistent with the eye phenotypes observed in the patients, which range from bilateral anophthalmia to retinal defects resembling Leber congenital amaurosis and pigmentary retinopathy. Magnetic resonance imaging scans revealed defects of the optic nerve, optic chiasm, and, in some cases, brain. In two families, the mutations appear to have occurred de novo in severely affected offspring, and, in two other families, the mutations have been inherited from a gonosomal mosaic parent. Data from these four families support a simple model in which OTX2 heterozygous loss-of-function mutations cause ocular malformations. Four additional families display complex inheritance patterns, suggesting that OTX2 mutations alone may not lead to consistent phenotypes. The high incidence of mosaicism and the reduced penetrance have implications for genetic counseling.

Amino Acid Motifs↗

PubMed1998

Mutation at the anophthalmic white locus in Syrian hamsters: haploinsufficiency in the Mitf gene mimics human Waardenburg syndrome type 2.

Mutations in MITF (microphthalmia transcription factor) cause Waardenburg syndrome type 2 (WS2A) in humans, an autosomal dominant disorder consisting of deafness and hypopigmentation. Phenotypes vary significantly within WS2 pedigrees, and there is generally no correlation between the predicted biochemical properties of mutant MITF proteins and disease severity. We have identified a nonsense mutation in the Mitf gene of the anophthalmic white Wh) Syrian hamster that destabilizes its mRNA and prevents the encoded basic helix-loop-helix leucine zipper (bHLHzip) protein from dimerizing or binding DNA target sites. Although the resulting polypeptide does not act as a dominant-negative species in vitro , the Wh mutation is inherited as a semi-dominant trait. It thus more closely resembles WS2 than comparable Mitf alleles in laboratory mice and rats, which are expressed as purely recessive traits.

Amino Acid Sequence↗

PubMed2003

Mutations in the human RAX homeobox gene in a patient with anophthalmia and sclerocornea.

Anophthalmia and microphthalmia are among the most common ocular birth defects and a significant cause of congenital blindness. The etiology of anophthalmia and microphthalmia is diverse, with multiple genetic mutations associated with each of these conditions, along with potential environmental causes. Based on findings that mutations in the Rx/Rax homeobox genes in mice and fish lead to defects in retinal development and result in animal models of anophthalmia, we screened 75 individuals with anophthalmia and/or microphthalmia for mutations in the human RAX gene. We identified a single proband from this population who is a compound heterozygote for mutations in the RAX gene. This individual carries a truncated allele (Q147X) and a missense mutation (R192Q), both within the DNA-binding homeodomain of the RAX protein, and we have characterized the biochemical properties of these mutations in vitro. Parents and grandparents of the proband were found to be carriers without visible ocular defects, consistent with an autosomal recessive inheritance pattern. This is the first report of genetic mutations in the human RAX gene.

Anophthalmos↗

PubMed2005

Expression of the homeobox gene Pitx2 in neural crest is required for optic stalk and ocular anterior segment development.

Heterozygous mutations in the homeobox gene, PITX2, result in ocular anterior segment defects and a high incidence of early-onset glaucoma. Pitx2 is expressed in both the neural crest and the mesoderm-derived precursors of the periocular mesenchyme. Complete loss of function in mice results in agenesis or severe disruption of periocular mesenchyme structures and extrinsic defects in early optic nerve development. However, the specific requirements for Pitx2 in neural crest versus mesoderm could not be determined using these mice, and only roles in the initial stages of eye development could be assessed due to early embryonic lethality. To determine the specific roles of Pitx2 in the neural crest precursor pool, we generated neural crest-specific Pitx2 knockout mice (Pitx2-ncko). Because Pitx2-nkco mice are viable, we also analyzed gene function in later eye development. Pitx2 is intrinsically required in neural crest for specification of corneal endothelium, corneal stroma and the sclera. Pitx2 function in neural crest is also required for normal development of ocular blood vessels. Pitx2-ncko mice exhibit a unique optic nerve phenotype in which the eyes are progressively displaced towards the midline until they are directly attached to the ventral hypothalamus. As Pitx2 is not expressed in the optic stalk, an essential function of PITX2 protein in neural crest is to regulate an extrinsic factor(s) required for development of the optic nerve. We propose a revised model of optic nerve development and new mechanisms that may underlie the etiology of glaucoma in Axenfeld-Rieger patients.

Animals↗

PubMed2006

Mutations in SOX2 cause anophthalmia-esophageal-genital (AEG) syndrome.

We report heterozygous, loss-of-function SOX2 mutations in three unrelated individuals with Anophthalmia-Esophageal-Genital (AEG) syndrome. One previously reported case [Rogers, R.C. (1988) Unknown cases. Proceedings of the Greenwood Genetic Center. 7, 57.] has a 2.7 Mb deletion encompassing SOX2 and associated with a cryptic translocation t(3;7)(q28;p21.3). The deletion and translocation breakpoints on chromosome 3q are >8.6 Mb apart and both chromosome rearrangements have occurred de novo. Another published case [Petrackova et al. (2004) Association of oesophageal atresia, anophthalmia and renal duplex. Eur. J. Pediatr., 163, 333-334.] has a de novo nonsense mutation, Q55X. A previously unreported case with severe bilateral microphthalmia and oesophageal atresia has a de novo missense mutation, R74P, that alters a highly evolutionarily conserved residue within the high mobility group domain, which is critical for DNA-binding of SOX2. In a yeast one-hybrid assay, this mutation abolishes Sox2-induced activation of the chick delta-crystallin DC5 enhancer. Four other reported AEG syndrome cases were extensively screened and do not have detectable SOX2 mutations. Two of these cases have unilateral eye malformations. SOX2 mutations are known to cause severe bilateral eye malformations but this is the first report implicating loss of function mutations in this transcription factor in oesophageal malformations. SOX2 is expressed in the developing foregut in mouse and zebrafish embryos and an apparently normal pattern of expression is maintained in Shh-/- mouse embryos, suggesting either that Sox2 acts upstream of Shh or functions in a different pathway. Three-dimensional reconstructions of the major morphological events in the developing foregut and eye from Carnegie Stages 12 and 13 human embryos are presented and compared with the data from model organisms. SOX2, with NMYC and CHD7, is now the third transcriptional regulator known to be critical for normal oesophageal development in humans.

Animals↗

PubMed1996

The descriptive epidemiology of anophthalmia and microphthalmia.

BACKGROUND: Anophthalmia and microphthalmia are serious eye malformations which recently have been associated with exposure to Benomyl. Data on these malformations are scarce in the literature and reported prevalences at birth vary strongly. METHODS: Data from three large registers of congenital malformations were analysed and comprised 849 malformed infants based on close to 5.7 million births. RESULTS: This is the largest available epidemiological study on anophthalmia and microphthalmia. The prevalence at birth was 1.50 per 10,000, varying between 0.92 and 2.29 between registers but no varying significantly between races in the California register. The variation in rates was mainly due to different inclusion of chromosomally abnormal infants (mainly trisomy 13) and of infants with microphthalmia occurring with major non-eye malformations. On the other hand, rates of anophthalmia and isolated microphthalmia were similar. Other major non-eye malformations were found in 73% of infants without a known chromosome anomaly. The malformation was bilateral in 53-60% of infants except when microphthalmia existed without any other malformations when only 27% were bilateral. Sex distribution was normal, there was a slight excess of twins, and an increased risk at high maternal age. CONCLUSIONS: In analytical studies searching for the cause of these malformations, it may be useful to restrict the analysis to infants with anophthalmia or isolated microphthalmia as the recording of such cases seems to be more reliable than of microphthalmia occurring with other malformations. The conclusions presented in the literature on the possible effect of Benomyl are partly based on data with apparent very incomplete ascertainment.

Abnormalities, Multiple↗

PubMed1972