A Descriptive Analysis of Eight Remedial Reading Students in the Sevier District Schools

Authorities have variously estimated the number of children with a reading disability to be between ten and fifteen percent of the total school population.1,2,3 Formerly, many children who had reading difficulties perhaps left school at an early age. Also, many children who might have had reading problems perhaps remained undetected before widespread group testing was initiated. Today, with the high premium placed upon high school and even college achievement, an education is, so to speak, a prerequisite to adult success. With reading unique in its being both a subject area and a tool necessary for the mastery of other subject areas, any disability is worthy of concern and consideration

The mathematical modelling of cell kinetics in corneal epithelial wound healing

This paper considers the comparison of experimental spatial and temporal data of mitotic rates measured during corneal epithelial wound healing (CEWH) of a rat model with the predictions of a computer modelling framework. We begin by briefly showing that previous models, used in the study of corneal epithelial wound healing speeds, are inadequate for the study of cell kinetics. We proceed to formulate a new modelling framework more suited to such a study. This framework is simulated in its simplest form, and the results from this motivate a new realisation of the modelling framework, including a caricature of age structuring. Finally, a model with a simple representation of juxtacrine signalling is considered. The final model captures many, though not all, of the trends of the experimental data. This paper thus lays a foundation for the modelling of the cell kinetics of corneal epithelial wound healing, and yields valuable insight regarding the important mechanisms a model should consider in order to reproduce the observed experimental trends

Novel disease-causing variants and phenotypic features of X-linked megalocornea

Purpose: The aim of the study was to describe the phenotype and molecular genetic causes of X-linked megalocornea (MGC1). We recruited four British, one New Zealand, one Vietnamese and four Czech families. // Methods: All probands and three female carriers underwent ocular examination and Sanger sequencing of the CHRDL1 gene. Two of the probands also had magnetic resonance imaging (MRI) of the brain. // Results: We identified nine pathogenic or likely pathogenic and one variant of uncertain significance in CHRDL1, of which eight are novel. Three probands had ocular findings that have not previously been associated with MGC1, namely pigmentary glaucoma, unilateral posterior corneal vesicles, unilateral keratoconus and unilateral Fuchs heterochromic iridocyclitis. The corneal diameters of the three heterozygous carriers were normal, but two had abnormally thin corneas, and one of these was also diagnosed with unilateral keratoconus. Brain MRI identified arachnoid cysts in both probands, one also had a neuroepithelial cyst, while the second had a midsagittal neurodevelopmental abnormality (cavum septum pellucidum et vergae). // Conclusion: The study expands the spectrum of pathogenic variants and the ocular and brain abnormalities that have been identified in individuals with MGC1. Reduced corneal thickness may represent a mild phenotypic feature in some heterozygous female carriers of CHRDL1 pathogenic variants

Schnyder corneal dystrophy and associated phenotypes caused by novel and recurrent mutations in the UBIAD1 gene

BACKGROUND: The purpose of this study was to identify the genetic cause and describe the clinical phenotype of Schnyder corneal dystrophy (SCD) in six unrelated probands. METHODS: We identified two white Czech, two white British and two South Asian families with a clinical diagnosis of SCD. Ophthalmic assessment included spectral domain optical coherence tomography (SD-OCT) of one individual with advanced disease, and SD-OCT and confocal microscopy of a child with early stages of disease. UBIAD1 coding exons were amplified and Sanger sequenced in each proband. A fasting serum lipid profile was measured in three probands. Paternity testing was performed in one family. RESULTS: A novel heterozygous c.527G>A; p.(Gly176Glu) mutation in UBIAD1 was identified in one Czech proband. In the second Czech proband, aged 6 years when first examined, a previously described de novo heterozygous c.289G>A; p.(Ala97Thr) mutation was found. Two probands of South Asian descent carried a known c.305G>A; p.(Asn102Ser) mutation in the heterozygous state. Previously reported heterozygous c.361C>T; p.(Leu121Phe) and c.308C>T; p.(Thr103Ile) mutations were found in two white British families. Although crystalline deposits were present in all probands the affected area was small in some individuals. Corneal arcus and stromal haze were the most prominent phenotypical feature in two probands. In the Czech probands, SD-OCT confirmed accumulation of reflective material in the anterior stroma. Crystalline deposits were visualized by confocal microscopy. Mild dyslipidemia was found in all three individuals tested. CONCLUSION: Although de novo occurrence of mutations in UBIAD1 is extremely rare, SCD should be considered in the differential diagnosis of bilateral corneal haze and/or crystal deposition, especially in children

IPSC-Derived Corneal Endothelial-like Cells Act as an Appropriate Model System to Assess the Impact of SLC4A11 Variants on Pre-mRNA Splicing

Purpose: To report molecular genetic findings in six probands with congenital hereditary endothelial dystrophy (CHED) variably associated with hearing loss (also known as Harboyan syndrome). Furthermore, we developed a cellular model to determine if disease-associated variants induce aberrant SLC4A11 pre-mRNA splicing. Methods: Direct sequencing of the entire SLC4A11 coding region was performed in five probands. In one individual, whole genome sequencing was undertaken. The effect of c.2240+5G>A on pre-mRNA splicing was evaluated in a corneal endothelial-like (CE-like) cell model expressing SLC4A11. CE-like cells were derived from autologous induced pluripotent stem cells (iPSCs) via neural crest cells exposed to B27, PDGF-BB, and DKK-2. Total RNA was extracted, and RT-PCR was performed followed by Sanger and a targeted next generation sequencing (NGS) approach to identify and quantify the relative abundance of alternatively spliced transcripts. Results: In total, 11 different mutations in SLC4A11 evaluated as pathogenic were identified; of these, c.1237G>A, c.2003T>C, c.1216+1G>A, and c.2240+5G>A were novel. The c.2240+5G>A variant was demonstrated to result in aberrant pre-mRNA splicing. A targeted NGS approach confirmed that the variant introduces a leaky cryptic splice donor site leading to the production of a transcript containing an insertion of six base pairs with the subsequent introduction of a premature stop codon (p.Thr747*). Furthermore, a subset of transcripts comprising full retention of intron 16 also were observed, leading to the same functionally null allele. Conclusions: This proof-of-concept study highlights the potential of using CE-like cells to investigate the pathogenic consequences of SLC4A11 disease-associated variants

Dihydropyridine receptors and type 1 ryanodine receptors constitute the molecular machinery for voltage-induced Ca2+ release in nerve terminals

Ca2+ stores were studied in a preparation of freshly dissociated terminals from hypothalamic magnocellular neurons. Depolarization from a holding level of -80 mV in the absence of extracellular Ca2+ elicited Ca2+ release from intraterminal stores, a ryanodine-sensitive process designated as voltage-induced Ca2+ release (VICaR). The release took one of two forms: an increase in the frequency but not the quantal size of Ca2+ syntillas, which are brief, focal Ca2+ transients, or an increase in global [Ca2+]. The present study provides evidence that the sensors of membrane potential for VICaR are dihydropyridine receptors (DHPRs). First, over the range of -80 to -60 mV, in which there was no detectable voltage-gated inward Ca2+ current, syntilla frequency was increased e-fold per 8.4 mV of depolarization, a value consistent with the voltage sensitivity of DHPR-mediated VICaR in skeletal muscle. Second, VICaR was blocked by the dihydropyridine antagonist nifedipine, which immobilizes the gating charge of DHPRs but not by Cd2+ or FPL 64176 (methyl 2,5 dimethyl-4[2-(phenylmethyl)benzoyl]-1H-pyrrole-3-carboxylate), a non-dihydropyridine agonist specific for L-type Ca2+ channels, having no effect on gating charge movement. At 0 mV, the IC50 for nifedipine blockade of VICaR in the form of syntillas was 214 nM in the absence of extracellular Ca2+. Third, type 1 ryanodine receptors, the type to which DHPRs are coupled in skeletal muscle, were detected immunohistochemically at the plasma membrane of the terminals. VICaR may constitute a new link between neuronal activity, as signaled by depolarization, and a rise in intraterminal Ca2+

Brittle Cornea Syndrome ZNF469 mutation carrier phenotype and segregation analysis of rare ZNF469 variants in familial Keratoconus.

Purpose: Brittle cornea syndrome 1 (BCS1) is a rare recessive condition characterised by extreme thinning of the cornea and sclera, caused by mutations in ZNF469. Keratoconus is a relatively common disease characterised by progressive thinning and ectasia of the cornea. The aetiology of keratoconus is complex and not yet understood, but rare ZNF469 variants have recently been associated with disease. We investigated the phenotype of BCS1 carriers with known pathogenic ZNF469 mutations, and recruited families in which aggregation of keratoconus was observed to establish if rare variants in ZNF469 segregated with disease. Methods: Patients and family members were recruited and underwent comprehensive anterior segment examination including corneal topography. Blood samples were donated and genomic DNA was extracted. The coding sequence and splice sites of ZNF469 were PCR amplified and Sanger sequenced. Results: Four carriers of three BCS1-associated ZNF469 loss-of-function mutations (p.[ Glu1392Ter], p.[Gln1930Argfs*6], p.[Gln1930fs*133]) were examined and none had keratoconus. One carrier had partially penetrant features of BCS1, including joint hypermobility. ZNF469 sequencing in 11 keratoconus families identified 9 rare (MAF≤0.025) variants predicted to be potentially damaging. However, in each instance the rare variant(s) identified, including two previously reported as potentially keratoconus-associated, did not segregate with the disease. Conclusions: The presence of heterozygous loss-of-function alleles in the ZNF469 gene did not cause keratoconus in the individuals examined. None of the rare non-synonymous ZNF469 variants identified in the familial cohort conferred a high risk of keratoconus, therefore, genetic variants contributing to disease pathogenesis in these 11 families remain to be identified

Corneal melting after collagen cross-linking for keratoconus: a case report

<p>Abstract</p> <p>Introduction</p> <p>Corneal collagen cross-linking is a rather new technique that uses riboflavin and ultraviolet A light for collagen fiber stabilization in keratoconus corneas. Other than reversible side effects, the preliminary results of corneal collagen cross-linking studies suggest that it is a rather safe technique. In this report, we demonstrate a case of corneal melting after corneal collagen cross-linking for keratoconus corneas associated with an acute inflammatory response.</p> <p>Case presentation</p> <p>A 23-year-old Caucasian man with keratoconus cornea stage 1 to 2 underwent uneventful corneal collagen cross-linking treatment according to the Dresden protocol. The next day the patient had intense photophobia, watering and redness of the eye, and his visual acuity was limited to counting fingers. Slit lamp biomicroscopy revealed severe corneal haze accompanied by non-specific endothelial precipitates following an acute inflammatory response. Mild inflammation could be detected in the anterior chamber. Moreover, the re-epithelialization process could barely be detected. His corneal state gradually deteriorated, resulting in descemetocele and finally perforation.</p> <p>Conclusion</p> <p>In this report, we present a case of a patient with corneal melting after standard corneal collagen cross-linking treatment for keratoconus corneas following an acute inflammatory response. Despite modifying postoperative treatment, elaboration of all apparent associated causes by the treating physicians and undergoing extensive laboratory testing, the patient developed descemetocele, which led to perforation. Our report suggests that further research is necessary regarding the safety of corneal collagen cross-linking in keratoconus corneas.</p

Ectopic GRHL2 Expression Due to Non-coding Mutations Promotes Cell State Transition and Causes Posterior Polymorphous Corneal Dystrophy 4

In a large family of Czech origin, we mapped a locus for an autosomal-dominant corneal endothelial dystrophy, posterior polymorphous corneal dystrophy 4 (PPCD4), to 8q22.3-q24.12. Whole-genome sequencing identified a unique variant (c.20+544G>T) in this locus, within an intronic regulatory region of GRHL2. Targeted sequencing identified the same variant in three additional previously unsolved PPCD-affected families, including a de novo occurrence that suggests this is a recurrent mutation. Two further unique variants were identified in intron 1 of GRHL2 (c.20+257delT and c.20+133delA) in unrelated PPCD-affected families. GRHL2 is a transcription factor that suppresses epithelial-to-mesenchymal transition (EMT) and is a direct transcriptional repressor of ZEB1. ZEB1 mutations leading to haploinsufficiency cause PPCD3. We previously identified promoter mutations in OVOL2, a gene not normally expressed in the corneal endothelium, as the cause of PPCD1. OVOL2 drives mesenchymal-to-epithelial transition (MET) by directly inhibiting EMT-inducing transcription factors, such as ZEB1. Here, we demonstrate that the GRHL2 regulatory variants identified in PPCD4-affected individuals induce increased transcriptional activity in vitro. Furthermore, although GRHL2 is not expressed in corneal endothelial cells in control tissue, we detected GRHL2 in the corneal "endothelium" in PPCD4 tissue. These cells were also positive for epithelial markers E-Cadherin and Cytokeratin 7, indicating they have transitioned to an epithelial-like cell type. We suggest that mutations inducing MET within the corneal endothelium are a convergent pathogenic mechanism leading to dysfunction of the endothelial barrier and disease