Intrauterine Cataract Diagnosis and Follow-up

In this article, we report a 21-gestational-week fetus diagnosed with congenital cataract by ultrasonography. The parents decided to terminate the pregnancy and asked for examination of the fetus. An amniocentesis was performed for fetal karyotyping. After termination of the pregnancy, fetal autopsy was conducted. Whole exome sequencing (Trio-WES) analysis of the mother and father was done from peripheral blood samples. In the pathologic autopsy report, bilateral anterior and posterior subcapsular cataracts were confirmed. Whole exome sequencing analysis revealed a previously unreported class 3 variant of uncertain significance (c755A>G [P.Lys252Arg]) of the CRYBB1 gene, which is associated with congenital cataract, that was homozygous in the fetus and heterozygous in the parents. The obtained result is consistent with a genetic diagnosis of isolated autosomal recessive cataract.

OFCD syndrome and extraembryonic defects are revealed by conditional mutation of the Polycomb-group repressive complex 1.1 (PRC1.1) gene BCOR.

BCOR is a critical regulator of human development. Heterozygous mutations of BCOR in females cause the X-linked developmental disorder Oculofaciocardiodental syndrome (OFCD), and hemizygous mutations of BCOR in males cause gestational lethality. BCOR associates with Polycomb group proteins to form one subfamily of the diverse Polycomb repressive complex 1 (PRC1) complexes, designated PRC1.1. Currently there is limited understanding of differing developmental roles of the various PRC1 complexes. We therefore generated a conditional exon 9-10 knockout Bcor allele and a transgenic conditional Bcor expression allele and used these to define multiple roles of Bcor, and by implication PRC1.1, in mouse development. Females heterozygous for Bcor exhibiting mosaic expression due to the X-linkage of the gene showed reduced postnatal viability and had OFCD-like defects. By contrast, Bcor hemizygosity in the entire male embryo resulted in embryonic lethality by E9.5. We further dissected the roles of Bcor, focusing on some of the tissues affected in OFCD through use of cell type specific Cre alleles. Mutation of Bcor in neural crest cells caused cleft palate, shortening of the mandible and tympanic bone, ectopic salivary glands and abnormal tongue musculature. We found that defects in the mandibular region, rather than in the palate itself, led to palatal clefting. Mutation of Bcor in hindlimb progenitor cells of the lateral mesoderm resulted in 2/3 syndactyly. Mutation of Bcor in Isl1-expressing lineages that contribute to the heart caused defects including persistent truncus arteriosus, ventricular septal defect and fetal lethality. Mutation of Bcor in extraembryonic lineages resulted in placental defects and midgestation lethality. Ubiquitous over expression of transgenic Bcor isoform A during development resulted in embryonic defects and midgestation lethality. The defects we have found in Bcor mutants provide insights into the etiology of the OFCD syndrome and how BCOR-containing PRC1 complexes function in development.

Deletion of Seventeen Amino Acids at the C-Terminal End of Aquaporin 0 Causes Distortion Aberration and Cataract in the Lenses of AQP0ΔC/ΔC Mice.

Purpose: Investigate the effects of the absence of 17 amino acids at the C-terminal end of Aquaporin 0 (AQP0) on lens transparency, focusing property, and homeostasis. Methods: A knockin (KI) mouse model (AQP0ΔC/ΔC) was developed to express AQP0 only as the end-cleaved form in the lens. For this, AQP0 was genetically engineered as C-terminally end-cleaved with amino acids 1 to 246, instead of the full length 1 to 263 of the wild type (WT). After verifying the KI integration into the genome and its expression, the mouse model was bred for several generations. AQP0 KI homozygous (AQP0ΔC/ΔC) and heterozygous (AQP0+/ΔC) lenses were imaged and analyzed at different developmental stages for transparency. Correspondingly, aberrations in the lens were characterized using the standard metal grid focusing method. Data were compared with age-matched WT, AQP0 knockout (AQP0-/-), and AQP0 heterozygous (AQP0+/-) lenses. Results: AQP0ΔC/ΔC lenses were transparent throughout the embryonic development and until postnatal day 15 (P15) in contrast to age-matched AQP0-/- lenses, which developed cataract at embryonic stage itself. However, there was distortion aberration in AQP0ΔC/ΔC lens at P5; after P15, cataract began to develop and progressed faster surpassing that of age-matched AQP0-/- lenses. AQP0+/ΔC lenses were transparent even at the age of 1 year in contrast to AQP0+/- lenses; however, there was distortion aberration starting at P15. Conclusions: A specific distribution profile of intact and end-cleaved AQP0 from the outer cortex to the inner nucleus is required in the lens for establishing refractive index gradient to enable proper focusing without aberrations and for maintaining transparency.

iSyTE 2.0: a database for expression-based gene discovery in the eye.

Although successful in identifying new cataract-linked genes, the previous version of the database iSyTE (integrated Systems Tool for Eye gene discovery) was based on expression information on just three mouse lens stages and was functionally limited to visualization by only UCSC-Genome Browser tracks. To increase its efficacy, here we provide an enhanced iSyTE version 2.0 (URL: http://research.bioinformatics.udel.edu/iSyTE) based on well-curated, comprehensive genome-level lens expression data as a one-stop portal for the effective visualization and analysis of candidate genes in lens development and disease. iSyTE 2.0 includes all publicly available lens Affymetrix and Illumina microarray datasets representing a broad range of embryonic and postnatal stages from wild-type and specific gene-perturbation mouse mutants with eye defects. Further, we developed a new user-friendly web interface for direct access and cogent visualization of the curated expression data, which supports convenient searches and a range of downstream analyses. The utility of these new iSyTE 2.0 features is illustrated through examples of established genes associated with lens development and pathobiology, which serve as tutorials for its application by the end-user. iSyTE 2.0 will facilitate the prioritization of eye development and disease-linked candidate genes in studies involving transcriptomics or next-generation sequencing data, linkage analysis and GWAS approaches.

[Embryological aspects of clinical presentations of congenital lens and vitreous anomalies]. / Émbriologicheskie aspekty klinicheskikh proiavlenii vrozhdennykh izmenenii khrustalika i steklovidnogo tela.

This report gives a general overview of embryological features of the human eye. Key literature sources published during the last century on evaluation of congenital changes in the vitreous body and identification of signs of its 'underdevelopment' in certain types of congenital cataracts have been studied. The said changes were analyzed in terms of general pathology of the human body as well as local morphological manifestations. According to the authors, such an approach justifies the need for comparison of clinical manifestations of congenital lens and vitreous changes with possible embryonic defects.

The endocytic recycling regulatory protein EHD1 Is required for ocular lens development.

The C-terminal Eps15 homology domain-containing (EHD) proteins play a key role in endocytic recycling, a fundamental cellular process that ensures the return of endocytosed membrane components and receptors back to the cell surface. To define the in vivo biological functions of EHD1, we have generated Ehd1 knockout mice and previously reported a requirement of EHD1 for spermatogenesis. Here, we show that approximately 56% of the Ehd1-null mice displayed gross ocular abnormalities, including anophthalmia, aphakia, microphthalmia and congenital cataracts. Histological characterization of ocular abnormalities showed pleiotropic defects that include a smaller or absent lens, persistence of lens stalk and hyaloid vasculature, and deformed optic cups. To test whether these profound ocular defects resulted from the loss of EHD1 in the lens or in non-lenticular tissues, we deleted the Ehd1 gene selectively in the presumptive lens ectoderm using Le-Cre. Conditional Ehd1 deletion in the lens resulted in developmental defects that included thin epithelial layers, small lenses and absence of corneal endothelium. Ehd1 deletion in the lens also resulted in reduced lens epithelial proliferation, survival and expression of junctional proteins E-cadherin and ZO-1. Finally, Le-Cre-mediated deletion of Ehd1 in the lens led to defects in corneal endothelial differentiation. Taken together, these data reveal a unique role for EHD1 in early lens development and suggest a previously unknown link between the endocytic recycling pathway and regulation of key developmental processes including proliferation, differentiation and morphogenesis.

Effect of astaxanthin on cataract formation induced by glucocorticoids in the chick embryo.

PURPOSE: To examine whether astaxanthin (AST) prevent the cataract formation induced by glucocorticoid in chick embryo. MATERIALS AND METHODS: Hydrocortisone hemisuccinate sodium (HC) (0.5 µmol/egg) was administered directly into the air chamber in the egg shell of chick embryo day 15. The eggs were then kept in an incubator at same conditions and administered 100 µL of 50 (HC + AST50 group), 80 (HC + AST80 group), 100 (HC + AST100 group) mg/mL of AST solutions dissolved in dimethyl sulfoxide (DMSO) 3 h after administration of HC. In addition, non-HC treated group (treated with physiological saline without HC and 100 µL of DMSO), HC-alone group (treated with 0.5 µmol of HC and 100 µL of DMSO), and AST100 group (treated with physiological saline without HC and 100 µL of DMSO) were also incorporated. After 48 h of treatment, lenses were removed from embryo and classified into five stages according to developed opacity. The amounts of reduced glutathione in the lenses and the blood glucose levels were measured. RESULTS: The average scores of lens opacitiy were 2.63 ± 1.02 nmol/lens (HC-alone), 2.78 ± 0.97 nmol/lens (HC + AST50), 2.22 ± 1.20 nmol/lens (HC + AST80) and 1.84 ± 0.83 nmol/lens (HC + AST100; p < 0.05), respectively. Administration of AST decreased the lens opacity dose-dependently. The amounts of reduced glutathione in lenses were 11.6 ± 2.8 nmol/lens (HC-alone), 11.3 ± 2.7 nmol/lens (HC + AST50), 13.4 ± 2.4 nmol/lens (HC + AST80) and 13.7 ± 3.1 nmol/lens (HC + AST100; p < 0.05), respectively. Higher levels of AST prevented loss of reduced glutathione from the lens. CONCLUSION: These findings support that AST protects glucocorticoid-induced cataract in chick embryo.

Chicken embryos as a potential new model for early onset type I diabetes.

Diabetic retinopathy (DR) is the leading cause of blindness among the American working population. The purpose of this study is to establish a new diabetic animal model using a cone-dominant avian species to address the distorted color vision and altered cone pathway responses in prediabetic and early diabetic patients. Chicken embryos were injected with either streptozotocin (STZ), high concentration of glucose (high-glucose), or vehicle at embryonic day 11. Cataracts occurred in varying degrees in both STZ- and high glucose-induced diabetic chick embryos at E18. Streptozotocin-diabetic chicken embryos had decreased levels of blood insulin, glucose transporter 4 (Glut4), and phosphorylated protein kinase B (pAKT). In STZ-injected E20 embryos, the ERG amplitudes of both a- and b-waves were significantly decreased, the implicit time of the a-wave was delayed, while that of the b-wave was significantly increased. Photoreceptors cultured from STZ-injected E18 embryos had a significant decrease in L-type voltage-gated calcium channel (L-VGCC) currents, which was reflected in the decreased level of L-VGCCα1D subunit in the STZ-diabetic retinas. Through these independent lines of evidence, STZ-injection was able to induce pathological conditions in the chicken embryonic retina, and it is promising to use chickens as a potential new animal model for type I diabetes.

Deletion of autophagy-related 5 (Atg5) and Pik3c3 genes in the lens causes cataract independent of programmed organelle degradation.

The lens of the eye is composed of fiber cells, which differentiate from epithelial cells and undergo programmed organelle degradation during terminal differentiation. Although autophagy, a major intracellular degradation system, is constitutively active in these cells, its physiological role has remained unclear. We have previously shown that Atg5-dependent macroautophagy is not necessary for lens organelle degradation, at least during the embryonic period. Here, we generated lens-specific Atg5 knock-out mice and showed that Atg5 is not required for lens organelle degradation at any period of life. However, deletion of Atg5 in the lens results in age-related cataract, which is accompanied by accumulation of polyubiquitinated and oxidized proteins, p62, and insoluble crystallins, suggesting a defect in intracellular quality control. We also produced lens-specific Pik3c3 knock-out mice to elucidate the possible involvement of Atg5-independent alternative autophagy, which is proposed to be dependent on Pik3c3 (also known as Vps34), in lens organelle degradation. Deletion of Pik3c3 in the lens does not affect lens organelle degradation, but it leads to congenital cataract and a defect in lens development after birth likely due to an impairment of the endocytic pathway. Taken together, these results suggest that clearance of lens organelles is independent of macroautophagy. These findings also clarify the physiological role of Atg5 and Pik3c3 in quality control and development of the lens, respectively.

Prenatal ultrasonographic detection of ophthalmic diseases.

Four patients with prenatal sonographic findings suggestive of ophthalmic pathology were detected in utero. The definitive diagnoses of infantile fibrosarcoma, persistent hyperplastic primary vitreous/persistent fetal vasculature, Fraser syndrome, and microphthalmia with coloboma and retrobulbar cyst were made postnatally. High-resolution intrauterine sonograms expedited ophthalmic referral and influenced prenatal planning.