Behavior in Drosophila melanogaster. A geneticist's view.
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Alleles↗
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Results for “Eye Abnormalities”
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Colobomas in non-human primates.
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Animals↗
Variability of clinical phenotype in a large Alport family with Gly 1143 Ser change of collagen alpha 5(IV)-chain.
In a large Italian family with adult-onset Alport syndrome, molecular analysis of the COL4A5 gene, which encodes the alpha 5(IV)-chain of glomerular basement membrane collagen, revealed a GGC-->AGC change in exon 38, resulting in substitution of a serine for a glycine in position 1143 of the polypeptide chain, between interruptions 19 and 20 of the triple helical domain. The mutation leads to loss of a restriction site for the enzyme Msp I, and could thus be easily recognized in several female and male relatives. Among relatives of both sexes who carried the same mutation, the clinical phenotype of Alport syndrome was variable as for the onset of renal failure and the presence of associated ear and eye abnormalities.
Adolescent↗
Fetal facial defects: associated malformations and chromosomal abnormalities.
During an 8-year period, facial defects were observed in 146 (7%) of the 2,086 fetuses that underwent karyotyping in our unit because of fetal malformations and/or growth retardation. Chromosomal abnormalities were detected in 37 of 56 (66%) fetuses with micrognathia, in 10 of 13 (77%) with macroglossia, in 31 of 64 (48%) with cleft lip and palate, in 5 of 11 (45%) with severe hypotelorism or cyclops, and in 6 of 19 (32%) with nasal hypoplasia, proboscis or single nostril. Macroglossia was mainly associated with trisomy 21, micrognathia with trisomy 18 and triploidy, facial cleft with trisomies 13 and 18, and ocular or nasal defects with trisomy 13. In all chromosomally abnormal fetuses with facial defects, there were additional multisystem defects, and the pattern of these malformations was compatible with the type of the underlying chromosomal abnormality. In the total series of 2,086 fetuses with malformations and/or growth retardation, there were 31 with trisomy 13, 83 with trisomy 18 and 69 with trisomy 21; facial defects were found in 71, 36 and 14% of these fetuses, respectively.
Abnormalities, Multiple↗
[Congenital anomalies and mechanism of the first part of the lacrimal apparatus].
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Congenital Abnormalities↗
Survey of major blinding conditions in Qatar.
Qatar is one of the rapidly developing Gulf States. Its life style is rapidly changing from a seminomadic to a more settled urban one. This is the first study of the causes of economic blindness (6/60) in Qatar. It embraces 3,072 patients (70% males and 30% females). The most common causes in those under 40 years of age were trachoma, infectious diseases, retinal diseases, trauma and congenital malformations. After 40 years, cataract and glucoma occupy the second and third commonest causes after trachoma. Thus, a proper antitrachoma campaign will cut down the incidence of blidness by 50%. Control of individual behavior and antenatal caution in prescribing medicines can reduce the risk of trauma and congenital malformations. Cataract is not preventable, but early detection of glaucoma delays the damage of ocular tissues. This is the same with systemic disease.
Adolescent↗
Intraocular and extraocular colobomatous cysts in adults.
A 29-year-old woman had a colobomatous multiloculated cystic left eyeball. None of the normal structures of the globe were discernable by clinical examination. The cyst had been present since birth and had not grown in size since early childhood. Another patient, a man of 73, had an intraocular colobomatous cyst occupying the temporal half of the large choroidal bridge coloboma in his left eye. This cyst was partially filled with shimmering crystalline fluid. This patient had bilateral open-angle glaucoma which had caused advanced damage to the optic nerve in the structurally normal right eye. It is interesting that glaucoma did not affect the left eye with choroidal coloboma and intraocular colobomatous cyst, which had normal vision. The author thinks that ectatic sclera in the area of coloboma might have protected the eye from elevated intraocular pressure.
Adult↗
Functional characterization of connexin43 mutations found in patients with oculodentodigital dysplasia.
Specific mutations in GJA1, the gene encoding the gap junction protein connexin43 (Cx43), cause an autosomal dominant disorder called oculodentodigital dysplasia (ODDD). Here, we characterize the effects of 8 of these mutations on Cx43 function. Immunochemical studies have shown that most of the mutant proteins formed gap junction plaques at the sites of cell-cell apposition. However, 2 of the mutations (a codon duplication in the first extracellular loop, F52dup, and a missense mutation in the second extracellular loop, R202H, produced full-length connexins that failed to properly form gap junction plaques. Cx43 proteins containing ODDD mutations found in the N-terminus (Y17S), first transmembrane domain (G21R, A40V), second transmembrane domain (L90V), and cytoplasmic loop (I130T, K134E) do form gap junction plaques but show compromised channel function. L90V, I130T, and K134E demonstrated a significant decrease in junctional conductance relative to Cx43WT. Mutations Y17S, G21R, and A40V demonstrated a complete lack of functional electrical coupling even in the presence of significant plaque formation between paired cells. Heterologous channels formed by coexpression of Cx43WT and mutation R202H resulted in electrically functional gap junctions that were not permeable to Lucifer yellow. Therefore, the mutations found in ODDD not only cause phenotypic variability, but also result in various functional consequences. Overall, our data show an extensive range of molecular phenotypes, consistent with the pleiotropic nature of the clinical syndrome as a whole.
Abnormalities, Multiple↗
Norrie gene product is necessary for regression of hyaloid vessels.
PURPOSE: To investigate the nature and origin of the vitreous membranes in mice with knock-out of the Norrie gene product (ND mice). METHODS: Eighty-two eyes of ND mice of different age groups (postnatal day [P]0-13 months) and 95 age-matched wild-type control mice were investigated. In vitreoretinal wholemounts and in sagittal sections, vessels and free cells were visualized by labeling for lectin. In addition, staining with a marker for macrophages (F4/80) and collagen XVIII/endostatin known to be involved in regression of hyaloid vessels was performed for light and electron microscopic investigations. Endostatin expression was confirmed by Western blot analysis. RESULTS: Wild-type controls showed the typical pattern of hyaloid vessels, their regression and concomitantly retinal vasculogenesis and angiogenesis. Hyaloid vessels all stained for endostatin, whereas retinal vessels remained unstained. In ND mice, 1 to 5 days after birth, the hyaloid and retinal vasculatures were comparable to that in control mice. The hyaloid vessels also stained for endostatin. Numerous F4/80-positive cells were present adjacent to the vessels. With increasing age, only a few connecting branches of the hyaloid vessels regressed. Even in old mice most of the hyaloid vessels persisted. The vessels still stained for endostatin. Retinal angiogenesis was impaired. CONCLUSIONS: Retrolental membranes in ND mice consist of persistent hyaloid vessels, indicating that the ND gene product is important for the process of regression of these vessels. The ND gene product neither influences endostatin expression nor the presence of macrophages.
Animals↗
The changing patterns of ocular problems in childhood.
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Child↗
Joubert syndrome: monozygotic twins with discordant phenotypes.
We describe three sisters with Joubert syndrome, two of whom are monozygotic twins with highly discordant phenotypes. The twins were born at 34 weeks' gestation with discordant birthweights. Their anatomic, neurologic, and developmental status differs greatly: Twin B is able to walk, run, and is verbal, unlike Twin A who is wheelchair-bound, severely retarded, nonverbal, and autistic. Abnormal eye movements and retinal dysplasia are striking features in all three girls, but none has renal cysts seen by ultrasonography. Magnetic resonance images show the "molar tooth sign," the radiologic hallmark of Joubert syndrome, although only one twin, the most severely handicapped, has severe hypoplasia of the cerebellar hemispheres. Phenotypic differences between the twins could be attributable to postzygotic unequal division of the inner cell mass, unequal sharing of the venous return from a monochorionic placenta, mosaicism, or a mutation of a modifying gene.
Cerebellum↗
Clinical nosologic and genetic aspects of Joubert and related syndromes.
Joubert syndrome is an autosomal-recessive disorder characterized by cerebellar hypoplasia, hypotonia, developmental delay, abnormal respiratory patterns, and abnormal eye movements. The biochemical and genetic basis of Joubert syndrome is unknown and a specific chromosomal locus for this disorder has not been identified. Review of this disorder and related syndromes suggests that (1) hypoplasia of the cerebellar vermis in Joubert syndrome is frequently associated with a complex brain stem malformation represented as the "molar tooth sign" on magnetic resonance imaging, (2) the "molar tooth sign" could be present in association with the Dandy-Walker malformation and occipital encephalocele, (3) cerebellar hypoplasia is present in conditions related to Joubert syndrome such as Arima syndrome; Senior-Loken syndrome; cerebellar vermian hypoplasia, oligophrenia, congenital ataxia, coloboma, and hepatic fibrosis syndrome; and juvenile nephronophthisis due to NPH1 mutations, and (4) the brainstem-vermis malformation spectrum is probably caused by at least two and probably several genetic loci. We have ascertained previously a cohort of 50 patients with a putative diagnosis of Joubert syndrome in order to evaluate the presence of associated malformations, and to initiate studies leading to the identification of genes causing Joubert and related syndromes. Among the associated malformations found in patients ascertained as having Joubert syndrome, 8% of patients had polydactyly, 4% had ocular colobomas, 2% had renal cysts, and 2% had soft-tissue tumors of the tongue. The WNT1 gene has been tested as a candidate gene for Joubert syndrome based on its expression in the developing cerebellum and an associated mutation in the swaying mouse. A search for mutations in WNT1 in a series of patients with Joubert syndrome did not detect mutations at this locus. This analysis suggested that mutations in WNT1 might not have a significant role in Joubert syndrome, and other functional candidate genes related to development of the cerebellum need to be examined. A genome-wide linkage analysis carried out in 10 Joubert syndrome pedigrees did not identify a specific chromosomal locus for this disorder. This observation, along with those from clinical studies, provides further evidence that Joubert and related syndromes are genetically heterogeneous.
Animals↗
Eye and neural defects associated with loss of GDF6.
BACKGROUND: In Xenopus the bone morphogenetic protein growth and differentiation factor 6 (GDF6) is expressed at the edge of the neural plate, and within the anterior neural plate including the eye fields. Here we address the role of GDF6 in neural and eye development by morpholino knockdown experiments. RESULTS: We show that depletion of GDF6 (BMP13) resulted in a reduction in eye size, loss of laminar structure and a reduction in differentiated neural cell types within the retina. This correlated with a reduction in staining for Smad1/5/8 phosphorylation indicating a decrease in GDF6 signalling through loss of phosphorylation of these intracellular mediators of bone morphogenetic protein (BMP) signalling. In addition, the Pax6 expression domain is reduced in size at early optic vesicle stages. Neural cell adhesion molecule (NCAM) is generally reduced in intensity along the neural tube, while in the retina and brain discreet patches of NCAM expression are also lost. GDF6 knock down resulted in an increase in cell death along the neural tube and within the retina as determined by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining. CONCLUSION: Our data demonstrate that GDF6 has an important role in neural differentiation in the eye as well as within the central nervous system, and that GDF6 may act in some way to maintain cell survival within the ectoderm, during the normal waves of programmed cell death.
Animals↗
PAX6 mutations: genotype-phenotype correlations.
BACKGROUND: The PAX6 protein is a highly conserved transcriptional regulator that is important for normal ocular and neural development. In humans, heterozygous mutations of the PAX6 gene cause aniridia (absence of the iris) and related developmental eye diseases. PAX6 mutations are archived in the Human PAX6 Allelic Variant Database, which currently contains 309 records, 286 of which are mutations in patients with eye malformations. RESULTS: We examined the records in the Human PAX6 Allelic Variant Database and documented the frequency of different mutation types, the phenotypes associated with different mutation types, the contribution of CpG transitions to the PAX6 mutation spectrum, and the distribution of chain-terminating mutations in the open reading frame. Mutations that introduce a premature termination codon into the open reading frame are predominantly associated with aniridia; in contrast, non-aniridia phenotypes are typically associated with missense mutations. Four CpG dinucleotides in exons 8, 9, 10 and 11 are major mutation hotspots, and transitions at these CpG's account for over half of all nonsense mutations in the database. Truncating mutations are distributed throughout the PAX6 coding region, except for the last half of exon 12 and the coding part of exon 13, where they are completely absent. The absence of truncating mutations in the 3' part of the coding region is statistically significant and is consistent with the idea that nonsense-mediated decay acts on PAX6 mutant alleles. CONCLUSION: The PAX6 Allelic Variant Database is a valuable resource for studying genotype-phenotype correlations. The consistent association of truncating mutations with the aniridia phenotype, and the distribution of truncating mutations in the PAX6 open reading frame, suggests that nonsense-mediated decay acts on PAX6 mutant alleles.
Alleles↗
Behavioural symptoms among people with severe and profound intellectual disabilities: a 26-year follow-up study.
BACKGROUND: Very little is known about the natural history of challenging behaviour and psychiatric disorder in people with severe and profound degrees of intellectual disability. AIMS: To clarify the natural history of challenging behaviour and psychiatric disorder in this population through a longterm prospective cohort study over a 26-year period. METHOD: One hundred individuals with severe or profound intellectual disability were randomly selected in 1975. Their behaviour was recorded through carer and psychiatrist ratings using the Modified Manifest Abnormality Scale of the Clinical Interview Schedule. The presence and severity of psychiatric disorder were also recorded. The study was repeated in 1981/82 and 1992/93. We repeated the study again in 2001, supplementing the original observational data with the Checklist of Challenging Behaviour. RESULTS: Behavioural symptomatology is remarkably persistent, particularly stereotypy, emotional abnormalities, eye avoidance and overactivity, although the severity of overall psychiatric disorder does show some abatement through time. CONCLUSIONS: These findings influence the prospects of success in relocating adults with severe and profound degrees of intellectual disability back into the community.
Adolescent↗
PAX6 and congenital eye malformations.
The PAX6 gene is a paradigm for our understanding of the molecular genetics of mammalian eye development. Twelve years after its identification it is one of the most intensively studied genes, both in terms of its diverse and complex functions during oculogenesis and its role in an ever-increasing variety of human congenital eye malformations. The PAX6 field has benefited greatly from the continued input of clinicians, human geneticists and developmental biologists. This review summarizes the latest data on the PAX6 mutation spectrum and recent insights into Pax6 function from the mouse.
Animals↗
X chromosome-linked Kallmann syndrome: clinical heterogeneity in three siblings carrying an intragenic deletion of the KAL-1 gene.
Kallmann syndrome (KS) is characterized by the association of hypogonadotropic hypogonadism and anosmia. The gene underlying the X chromosome-linked form of the disease, KAL-1, consists of 14 coding exons. It encodes a glycoprotein, anosmin-1, which is involved in the embryonic migration of GnRH-synthesizing neurons and the differentiation of the olfactory bulbs. We describe herein the clinical heterogeneity in three affected brothers who carry a large deletion (exons 3-13) in KAL-1. All three had a history of hypogonadotropic hypogonadism with delayed puberty. Although brain magnetic resonance imaging showed hypoplastic olfactory bulbs in the three siblings, variable degrees of anosmia/hyposmia were shown by olfactometry. In addition, these brothers had different phenotypic anomalies, i.e. unilateral renal aplasia (siblings B and C), high-arched palate (sibling A), brachymetacarpia (sibling A), mirror movements (siblings A and B), and abnormal eye movements (sibling C). Last but not least, sibling A suffered from a severe congenital hearing impairment, a feature that had been reported in KS but had not yet been ascribed unambiguously to the X-linked form of the disease. The variable phenotype, both qualitatively and quantitatively, in this family further emphasizes the role of putative modifier genes, and/or epigenetic factors, in the expressivity of the X-linked KS.
Adolescent↗