Glaucoma genetics

Normal-Tension Glaucoma and Potential Clinical Links to Alzheimer's Disease

Glaucoma is a group of optic neuropathies and the world's leading cause of irreversible blindness. Normal-tension glaucoma (NTG) is a subtype of glaucoma that is characterized by a typical pattern of peripheral retinal loss, in which the patient's intraocular pressure (IOP) is considered within the normal range (<21 mmHg). Currently, the only targetable risk factor for glaucoma is lowering IOP, and patients with NTG continue to experience visual field loss after IOP-lowering treatments. This demonstrates the need for a better understanding of the pathogenesis of NTG and underlying mechanisms leading to neurodegeneration. Recent studies have found significant connections between NTG and cerebral manifestations, suggesting NTG as a neurodegenerative disease beyond the eye. Gaining a better understanding of NTG can potentially provide new Alzheimer's Disease diagnostics capabilities. This review identifies the epidemiology, current biomarkers, altered fluid dynamics, and cerebral and ocular manifestations to examine connections and discrepancies between the mechanisms of NTG and Alzheimer's Disease.

Primary Congenital Glaucoma among the Children Under 3 Years of Age in the Outpatient Department in a Tertiary Care Hospital: A Descriptive Cross-sectional Study

INTRODUCTION

Primary congenital glaucoma is a rare vision-threatening condition of children. Primary congenital glaucoma though a rare disease it is the most common cause of childhood glaucoma with potency to cause blindness. This study was undertaken to find the prevalence of the children with primary congenital glaucoma under 3 years of age in a tertiary care hospital.

METHODS

This was a descriptive cross-sectional study conducted at a tertiary eye center in Nepal in children (≤ 3 years) presented in the outpatient department of a tertiary eye hospital between June 2017 and June 2020. The study was approved by the hospital review committee and adhered to the declaration of Helsinki. A convenient sampling method was used. Point estimate at 95% Confidence Interval was calculated with frequency distribution. Data analysis was conducted using Statistical Package for the Social Sciences.

RESULTS

Out of total children under 3 years who presented to the outpatient department, 46 (0.31%) at 95% Confidence Interval (0.30-0.32) had primary congenital glaucoma. Among them, 30 children (65.2%) had bilateral involvement. Mean intraocular pressure was 42.40±8.15mm Hg. The mean age of initial presentation, horizontal corneal diameter, and axial length were 12.07±8.9 months, 12.95±1mm, and 23.89±1.7mm respectively. Consanguinity was observed in 12 (26%) children.

CONCLUSIONS

From the study, we conclude that there was a low prevalence of primary congenital glaucoma among children under 3 years of age who presented to the outpatient department in a tertiary care hospital.

Analysis of variants in Chinese individuals with primary open-angle glaucoma using molecular inversion probe (MIP)-based panel sequencing

Purpose

Family-based genetic linkage analysis and genome-wide association studies (GWASs) have identified many genomic loci associated with primary open-angle glaucoma (POAG). Several causative genes of POAG have been intensively analyzed by sequencing in different populations. However, few investigations have been conducted on the identification of variants of coding region in the genes identified in GWASs. Therefore, further research is needed to investigate whether they harbor pathogenically relevant rare coding variants and account for the observed association.

Methods

To identify the potentially disease-relevant variants (PDVs) in POAG-associated genes in Chinese patients, we applied molecular inversion probe (MIP)-based panel sequencing to analyze 26 candidate genes in 235 patients with POAG and 241 control subjects.

Results

The analysis identified 82 PDVs in 66 individuals across 235 patients with POAG. By comparison, only 18 PDVs in 19 control subjects were found, indicating an enrichment of PDVs in the POAG cohort (28.1% versus 7.9%, p = 8.629e-09). Among 26 candidate genes, the prevalence rate of PDVs in five genes showed a statistically significant difference between patients and controls (33 out of 235 versus 1 out of 241, p = 4.533e-10), including ATXN2 (p = 0.0033), TXNRD2 (p = 0.0190), MYOC (p = 0.0140), FOXC1 (p = 0.0140), and CDKN2B (p = 0.0287). Furthermore, two sisters harboring a stop-loss mutation EFEMP1 p.Ter494Glu were found in the POAG cohort, and further analysis of the family strongly suggested that EFEMP1 p.Ter494Glu was a potentially disease-causing mutation for POAG. A statistically significant difference in age at diagnosis between patients with PDVs and those without PDVs was found, implying that some of the identified PDVs may have a role in promoting the early onset of POAG disease.

Conclusions

The results suggest that some of the associations identified in POAG risk loci can be ascribed to rare coding variants with likely functional effects that modify POAG risk.

A novel mutation of FOXC1 in a Chinese family with Axenfeld-Rieger syndrome

Axenfeld-Rieger syndrome (ARS) is a disorder affecting the anterior segment of the eye and causing systemic malformations, and follows an autosomal-dominant inheritance pattern. The aim of the present study was to identify the underlying cause of ARS in a Chinese family. Genomic DNA was extracted from the peripheral blood of the subjects from a family with ARS. The pathogenic variant was identified by targeted next-generation sequencing and confirmed by Sanger sequencing. A novel heterozygous mutation of the forkhead box (FOX)C1 gene (c.1494delG, p.G499Afs*20) was detected in all affected members of the family, while no mutation was identified in the unaffected members or in the 150 normal controls. The affected members exhibited typical ocular and craniofacial anomalies. The results of the present study demonstrated that a novel deletion in exon 1 of the FOXC1 gene caused ARS in this Chinese family.

Mutation profile of glaucoma candidate genes in Mauritanian families with primary congenital glaucoma

Purpose

Intraocular pressure leading to glaucoma is a major cause of childhood blindness in developing countries. In this study, we sought to identify gene variants potentially associated with primary congenital glaucoma (PCG) in the Mauritanian population.

Methods

Using next-generation sequencing (NGS), a panel of PCG candidate genes was screened in a search for DNA mutations in four families with multiple occurrences of PCG.

Results

Targeted exome sequencing analysis revealed predicted pathogenic mutations in four genes: CYP1B1 (c.217_218delTC, p.Ser73Valfs*150), MYOC (878C>A, p.T293K), NTF4 (c.601T>G, p.Cys201Gly), and WDR36 (c.2078A>G, p.Asn693Ser), each carried by a different family.

Conclusions

Genetic variation associated with PCG in this study reflects the ethnic heterogeneity of the Mauritanian population. However, a larger cohort is needed to identify additional families carrying these mutations and confirm their biologic role.

Investigating a downstream gene of Gpnmb using the systems genetics method

Purpose

Glaucoma is characterized by optic nerve damage and retinal ganglion cell loss. The glycoprotein neuromedin B-associated (Gpnmb) gene is well-known to be involved in the glaucoma disease process. The purpose of this study is to identify a downstream gene through which Gpnmb affects the glaucoma phenotypes using a systems genetics approach.

Methods

Retinal gene expression data for the BXD recombinant inbred (RI) strains (n=75) have previously been generated in our laboratory for a glaucoma study, and these data were used for genetic and bioinformatics analysis. Expression quantitative trait locus (eQTL) mapping and genetic correlation methods were used to identify a gene downstream of Gpnmb. Gene-set enrichment analysis was used to evaluate gene function and to construct coexpression networks.

Results

The level of Gpnmb expression is associated with a highly statistically significant cis-eQTL. Stanniocalcin 1 (Stc1) has a significant trans-eQTL mapping to the Gpnmb locus. The expression of Gpnmb and Stc1 is highly correlated in the retina and other tissues, as well as with glaucoma-related phenotypes. Gene Ontology and pathway analysis showed that Stc1 and its covariates are highly associated with apoptosis, oxidative stress, and mitochondrial activity. A generated gene network indicated that Gpnmb and Stc1 are directly connected to and interact with other genes with similar biologic functions.

Conclusions

These results suggest that Stc1 may be a downstream candidate of Gpnmb, and that both genes interact with other genes in a network to develop glaucoma pathogenesis through mechanisms such as apoptosis and oxidative stress.

Heritability of glaucoma and glaucoma-related endophenotypes: systematic review and meta-analysis protocol

INTRODUCTION

Glaucoma is the second leading cause of age-related vision loss worldwide; it is an umbrella term that is used to describe a set of complex ocular disorders with a multifactorial aetiology. Both genetic and lifestyle risk factors for glaucoma are well established. Thus far, however, systematic reviews on the heritability of glaucoma have focused on the heritability of primary open-angle glaucoma only. No systematic review has comprehensively reviewed or meta-analysed the heritability of other types of glaucoma, including glaucoma-related endophenotypes. The aim of this study will be to identify relevant scientific literature regarding the heritability of both glaucoma and related endophenotypes and summarise the evidence by performing a systematic review and meta-analysis.

METHODS AND ANALYSIS

This systematic review will follow the Preferred Reporting Items for Systematic review and Meta-Analysis Protocols 2015 checklist, which provides a standardised approach for carrying out systematic reviews. To capture as much literature as possible, a comprehensive step-by-step systematic search will be undertaken in MEDLINE (PubMed), EMBASE, Web of Science and ScienceDirect, and studies published until 31 December 2017 will be included. Two reviewers will independently search the articles for eligibility according to predefined selection criteria. A database will be used for screening of eligible articles. The quality of the included studies will be rated independently by two reviewers, using the National Health Institute Quality Assessment tool for Observational Cohort and Cross-Sectional Studies. A random-effects model will be used for the meta-analysis. This systematic review is registered with the International Prospective Register of Systematic Reviews with a registration number: CRD42017064504.

ETHICS AND DISSEMINATION

We will use secondary data from peer-reviewed published articles, and hence there is no requirement for ethics approval. The results of this systematic review will be disseminated through publication in a peer-reviewed scientific journal.

The Association between TGF-β1 G915C (Arg25Pro) Polymorphism and the Development of Primary Open Angle Glaucoma: A Case-Control Study

The purpose of the current study was to identify the potential association between Single Nucleotide Polymorphism (SNP) TGFβ1 +915 (C or G) in codon 25 and Primary Open Angle Glaucoma (POAG). Overall, 88 cases with POAG and a control group of 52 healthy individuals were recruited from the First Ophthalmology Department of Athens University. DNA was isolated from whole blood samples and genotype frequencies for the polymorphism rs1800471 (G915C, Arg25Pro) of the TGF-β1 gene were assessed. Genotype distribution frequencies for the polymorphism rs1800471 (G915C, Arg25Pro) of the TGF-β1 gene were not statistically different between patients with POAG and control subjects. The present study failed to determine any significant genotypic association with POAG, despite the fact that the presence of the C allele was scarcely increased in the POAG when compared with the control group.

Novel Genetic Findings in a Chinese Family with Axenfeld-Rieger Syndrome

Purpose

To describe a Chinese family with Axenfeld-Rieger syndrome (ARS) and report our novel genetic findings.

Methods

Nine members of the same family underwent complete ophthalmologic examinations and genetic analysis. Genomic DNA was isolated from veinal blood and amplifed using PCR; the products of PCR were sequenced and compared with FOXC1 and PITX2 genes, from which the mutations were found.

Results

Through the ophthalmologic examinations, 8 subjects were diagnosed as ARS and 1 subject was normal. A homozygous mutation c.1139_1141dupGCG(p.Gly380_Ala381insGly) and a heterozygous mutation c.1359_1361dupCGG(p.Gly456_Gln457insGly) in FOXC1 were identified in all subjects. The mutation (c.-10-30T>C) was identified in PITX2 in subjects III-1 and III-3.

Conclusions

We found novel gene mutations in a Chinese family with ARS, which provides us with a better understanding of the gene mutation spectrum of ARS and the assistance for the genetic counseling and gene-specific therapy in the future.

A Family with Axenfeld-Rieger Syndrome: Report of the Clinical and Genetic Findings

PURPOSE

To describe clinical findings in a Korean family with Axenfeld-Rieger syndrome.

METHODS

A retrospective review of clinical data about patients with diagnosed Axenfeld-Rieger syndrome. Five affected members of the family underwent a complete ophthalmologic examination. We screened the forkhead box C1 gene and the pituitary homeobox 2 gene in patients. Peripheral blood leukocytes and buccal mucosal epithelial cells were obtained from seven members of a family with Axenfeld-Rieger syndrome. DNA was extracted and amplified by polymerase chain reaction, followed by direct sequencing.

RESULTS

The affected members showed iris hypoplasia, iridocorneal adhesions, posterior embryotoxon, and advanced glaucoma in three generation. None had systemic anomalies. Two mutations including c.1362_1364insCGG and c.1142_1144insGGC were identified in forkhead box C1 in four affected family members.

CONCLUSIONS

This study may help to understand clinical findings and prognosis for patients with Axenfeld-Rieger syndrome.

LOXL1-associated candidate epithelial pathomechanisms in exfoliation glaucoma

Results of the present study support ocular epithelia-specific LOXL1 functions in exfoliation glaucoma that may include both dysregulated extracellular matrix cross-linking activity and cellular mechanisms involving a role for LOXL1, in direct interaction with Snail1, in promoting epithelial to mesenchymal transition and a potential shift towards fibrogenic epithelial cell phenotypes.

The pathophysiology of eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is an emerging disease characterized by esophageal eosinophilia (>15eos/hpf), lack of responsiveness to acid-suppressive medication and is managed by allergen elimination and anti-allergy therapy. Although the pathophysiology of EoE is currently unsubstantiated, evidence implicates food and aeroallergen hypersensitivity in genetically predisposed individuals as contributory factors. Genome-wide expression analyses have isolated a remarkably conserved gene-expression profile irrespective of age and gender, suggesting a genetic contribution. EoE has characteristics of mainly TH2 type immune responses but also some TH1 cytokines, which appear to strongly contribute to tissue fibrosis, with esophageal epithelial cells providing a hospitable environment for this inflammatory process. Eosinophil-degranulation products appear to play a central role in tissue remodeling in EoE. This remodeling and dysregulation predisposes to fibrosis. Mast-cell-derived molecules such as histamine may have an effect on enteric nerves and may also act in concert with transforming growth factor-β to interfere with esophageal musculature. Additionally, the esophageal epithelium may facilitate the inflammatory process under pathogenic contexts such as in EoE. This article aims to discuss the contributory factors in the pathophysiology of EoE.

Survey of familial glaucoma shows a high incidence of cytochrome P450, family 1, subfamily B, polypeptide 1 (CYP1B1) mutations in non-consanguineous congenital forms in a Spanish population

PURPOSE

To identify myocilin (MYOC) and cytochrome P450, family 1, subfamily B, polypeptide 1 (CYP1B1) mutations in a Spanish population with different clinical forms of familial glaucoma or ocular hypertension (OHT).

METHODS

Index patients from 226 families participated in this study. Patients were diagnosed with familial glaucoma or OHT by complete ophthalmologic examination. Screening for MYOC mutations was performed in 207 index patients: 96 with adult-onset primary open-angle glaucoma (POAG), 21 with primary congenital glaucoma (PCG), 18 with juvenile-onset open-angle glaucoma (JOAG), five with Axenfeld-Rieger syndrome (ARS), and 67 with other types of glaucoma. One hundred two of the families (including all those in whom a MYOC mutation was detected) were also screened for CYP1B1 mutations: 45 POAG, 25 PCG, 21 JOAG, four ARS, and seven others.

RESULTS

We examined 292 individuals (patients and relatives) with a positive family history of glaucoma or OHT. We identified two novel MYOC variants, p.Lys39Arg and p.Glu218Lys, in two families with POAG, and six previously reported MYOC mutations in seven families with POAG (four), JOAG (one), PCG (one), and normotensive glaucoma (one). CYP1B1 mutations were found in 16 index patients with PCG (nine), POAG (three), JOAG (two), and ARS (two).

CONCLUSIONS

The high percentage (9/25=36%) of mutations in CYP1B1 found in non-consanguineous patients with congenital glaucoma mandates genetic testing. However, the percentage of mutations (9/207=4.4%) in MYOC associated with glaucoma is relatively low in our population. The variable phenotype expression of glaucoma, even in families, cannot be explained with a digenic mechanism between MYOC and CYP1B1.

Genetic, Biochemical and Clinical Insights into Primary Congenital Glaucoma

Glaucoma is an irreversible form of optic neuropathy in which the optic nerve suffers damage in a characteristic manner with optic nerve cupping and retinal ganglion cell death. Primary congenital glaucoma (PCG) is an idiopathic irreversible childhood blinding disorder which manifests at birth or within the first year of life. PCG presents with a classical triad of symptoms (viz epiphora, photophobia and blepharospasm) though there are many additional symptoms, including large eye ball and hazy cornea. The only anatomical anomaly found in PCG is trabecular meshwork (TM) dysgenesis. PCG is an inheritable disease with established genetic etiology. It transmits through autosomal recessive mode. A number of cases are sporadic also. Mutations in many genes have been found to be causative in PCG and many are yet to be found. Mutations in cytochrome P4501B1 (CYP1B1) gene have been found to be the predominant cause of PCG. Other genes that have been implicated in PCG etiology are myocilin, Forkhead-related transcription factor C1 (FOXC1) and latent transforming growth factor beta-binding protein 2 (LTBP2). Mutations in these genes have been reported from many parts of the world. In addition to this, mitochondrial genome mutations are also thought to be involved in its pathogenesis. There appears to be some mechanism involving more than one genetic factor. In this review, we will discuss the various clinical, biochemical and genetic aspects of PCG. We emphasize that etiology of PCG does not lie in a single gene or genetic factor. Research needs to be oriented into a direction where gene-gene interactions, ocular embryology, ophthalmic metabolism and systemic oxidative status need to be studied in order to understand this disorder. We also accentuate the need for ophthalmic genetic facilities in all ophthalmology setups. How to cite this article: Faiq M, Sharma R, Dada R, Mohanty K, Saluja D, Dada T. Genetic, Biochemical and Clinical Insights into Primary Congenital Glaucoma. J Current Glau Prac 2013;7(2):66-84.

The role of transforming growth factor β in glaucoma and the therapeutic implications

Glaucoma is a progressive optic neuropathy frequently associated with elevated intraocular pressure, ocular vascular changes and extracellular matrix remodelling at the optic nerve head and in the trabecular meshwork. The pathogenesis is multifactorial and complex, but many recent studies have suggested that transforming growth factor-β (TGF-β) plays a major role in the process. Significantly elevated levels of TGF-β have been identified in the anterior chamber of glaucomatous eyes. TGF-β has also been shown to directly cause increased intraocular pressure. It is believed that this occurs through complex interaction with the trabecular meshwork, leading to decreased aqueous humour outflow. These processes occur through specific interactions with various proteins and signalling molecules also present in ocular tissues. By understanding the role that TGF-β plays in the pathogenesis of glaucoma, alternative therapeutic agents can be developed, which target these pathways and improve and assist in the management of disease. This review will cover previous investigative studies and discuss the current understanding of TGF-β's role in glaucoma and how it may serve as a potential therapeutic target.

Analysis of ASB10 variants in open angle glaucoma

Glaucoma is a common cause of visual disability and affects ∼1.6% of individuals over 40 years of age ( 1). Non-synonymous coding sequence variations in the ankyrin repeat and SOCS box containing gene 10 (ASB10) were recently associated with 6.0% of cases of primary open angle glaucoma (POAG) in patients from Oregon and Germany. We tested a cohort of POAG patients (n= 158) and normal control subjects (n= 82), both from Iowa, for ASB10 mutations. Our study had 80% power to detect a 4.9% mutation frequency in POAG patients. A total of 11 non-synonymous coding sequence mutations were detected in the cohort, but no association with POAG was detected when analyzed individually or as a group (P > 0.05). Furthermore, a survey of the National Heart, Lung, and Blood Institute's (NHLBI's) Exome Sequencing Project revealed that non-synonymous ASB10 mutations are present in the general population at a far higher frequency than the prevalence of POAG. These data suggest that non-synonymous mutations in ASB10 do not cause Mendelian forms of POAG.

Copy number variations on chromosome 12q14 in patients with normal tension glaucoma

We report identification of a novel genetic locus (GLC1P) for normal tension glaucoma (NTG) on chromosome 12q14 using linkage studies of an African-American pedigree (maximum non-parametric linkage score = 19.7, max LOD score = 2.7). Subsequent comparative genomic hybridization and quantitative polymerase chain reaction (PCR) experiments identified a 780 kbp duplication within the GLC1P locus that is co-inherited with NTG in the pedigree. Real-time PCR studies showed that the genes within this duplication [TBK1 (TANK-binding kinase 1), XPOT, RASSF3 and GNS] are all expressed in the human retina. Cohorts of 478 glaucoma patients (including 152 NTG patients), 100 normal control subjects and 400 age-related macular degeneration patients were subsequently tested for copy number variation in GLC1P. Overlapping duplications were detected in 2 (1.3%) of the 152 NTG subjects, one of which had a strong family history of glaucoma. These duplications defined a 300 kbp critical region of GLC1P that spans two genes (TBK1 and XPOT). Microarray expression experiments and northern blot analysis using RNA obtained from human skin fibroblast cells showed that duplication of chromosome 12q14 results in increased TBK1 and GNS transcription. Finally, immunohistochemistry studies showed that TBK1 is expressed in the ganglion cells, nerve fiber layer and microvasculature of the human retina. Together, these data link the duplication of genes on chromosome 12q14 with familial NTG and suggest that an extra copy of the encompassed TBK1 gene is likely responsible for these cases of glaucoma. However, animal studies will be necessary to rule out a role for the other duplicated or neighboring genes.

Chromosome 7q31 POAG locus: ocular expression of caveolins and lack of association with POAG in a US cohort

PURPOSE

To determine the role of the recently discovered primary open angle glaucoma (POAG) risk factor mapped to chromosome 7q31 in glaucoma patients from Iowa and to determine the expression pattern of genes in the locus in human eyes.

METHODS

A cohort of 545 POAG patients and 297 control subjects from Iowa were genotyped with a single nucleotide polymorphism (SNP; rs4236601) in the chromosome 7q31 locus using a quantitative polymerase chain reaction (PCR) assay. The expression of genes within the 7q31 locus, caveolin-1 (CAV1) and caveolin-2 (CAV2) in human eyes was investigated with immunohistochemistry.

RESULTS

The minor allele frequency (MAF) of rs4236601 was 27% in control subjects and 29% in POAG patients. We detected no statistical difference when we compared the allele frequencies of rs4236601 between POAG patients and control subjects (p=0.5). Similarly, we detected no statistical difference in the frequency of the three possible rs4236601 genotypes between patients and controls (p=0.22). Immunohistochemistry showed caveolin expression in human retina, ciliary muscle, trabecular meshwork, and Schlemm's canal. In our small cohort of donor eyes, the genotype of rs4236601 did not obviously influence labeling intensity or distribution of CAV1 and CAV2 in the retina.

CONCLUSIONS

A genome-wide association study of subjects from Iceland mapped the first common genetic risk factor for POAG to a small region of the genome on chromosome 7q31 that contains the caveolin genes CAV1 and CAV2. We were unable to detect this association in our patients from Iowa, suggesting that this risk factor may not have a strong effect in all populations.

Screening of CYP1B1 and MYOC in Moroccan families with primary congenital glaucoma: three novel mutations in CYP1B1

PURPOSE

To investigate the contribution of cytochrome P4501B1 (CYP1B1) and myocillin (MYOC) mutations to primary congenital glaucoma (PCG) in Moroccan families.

METHODS

This study included 90 unrelated families with PCG and 100 normal control individuals. Two previously reported CYP1B1 mutations (g.4339delG and p.G61E) were first screened by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The coding exons of CYP1B1 were sequenced in g.4339delG- and p.G61E-negative or heterozygous probands. Then the coding exons of MYOC were sequenced in patients who had no mutation in CYP1B1 or carried heterozygous CYP1B1 mutation.

RESULTS

Twelve CYP1B1 mutations were identified in 43 PCG pedigrees. Three of them were novel (p.R163C, p.C470Y, and g.4330-4331delTG) and associated with moderate to severe phenotypes. Two novel intronic polymorphisms in CYP1B1 were identified in addition to those previously described. The g.4339delG was the most frequent mutation detected in 31 families (34.44%), followed by the p.G61E in seven families (7.77%). The remaining mutations (p.R163C, p.E173K, g.4330-4331delTG, p.E229K, p.R390S, p.R368H, p.R469W, p.C470Y, and g.7901-7913del13bp) were infrequent. One family with the p.R390S mutation showed both PCG and primary open angle glaucoma (POAG) phenotypes. One proband was heterozygous for p.T193K mutation in MYOC. This mutation has been initially associated with POAG, but never with PCG.

CONCLUSIONS

Our results support that mutations in CYP1B1 are a major cause for PCG in the Moroccan population with a predominance of the g.4339delG mutation. Furthermore, these results demonstrate the diversity of CYP1B1 mutations, while suggesting a modest role of MYOC in Moroccan PCG.

Common variants at 5q22 associate with pediatric eosinophilic esophagitis

Eosinophilic esophagitis (EoE) is an allergic disorder characterized by the accumulation of eosinophils in the esophagus. We report association of EoE with variants at chromosome 5q22 encompassing TSLP and WDR36 (rs3806932, combined P = 3.19 x 10(-9)). TSLP is overexpressed in esophageal biopsies from individuals with EoE compared with unaffected individuals, whereas WDR36 expression is unaltered between the two groups. These data implicate the 5q22 locus in the pathogenesis of EoE and identify TSLP as the most likely candidate gene in the region.

Elevated albumin in retinas of monkeys with experimental glaucoma

PURPOSE

To establish the identity of a prominent protein, approximately 70 kDa, that is markedly increased in the retina of monkeys with experimental glaucoma compared with the fellow control retina, the relationship to glaucoma severity, and its localization in the retina.

METHODS

Retinal extracts were subjected to 2-D gel electrophoresis to identify differentially expressed proteins. Purified peptides from the abundant 70 kDa protein were analyzed and identified by liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS) separation, and collision-induced dissociation sequencing. Protein identity was performed on MASCOT (Matrix Science, Boston, MA) and confirmed by Western blot. The relationship between the increase in this protein and glaucoma severity was investigated by regression analyses. Protein localization in retina was evaluated by immunohistochemistry with confocal imaging.

RESULTS

The abundant protein was identified as Macaca mulatta serum albumin precursor (67 kDa) from eight non-overlapping proteolytic fragments, and the identity was confirmed by Western blot. The average increase in retinal albumin content was 2.3 fold (P = 0.015). In glaucoma eyes, albumin was localized to some neurons of the inner nuclear layer, in the inner plexiform layer, and along the vitreal surface, but it was only found in blood vessels in control retinas.

CONCLUSIONS

Albumin is the abundant protein found in the glaucomatous monkey retinas. The increased albumin is primarily localized to the inner retina where oxidative damage associated with experimental glaucoma is known to be prominent. Since albumin is a major antioxidant, the increase of albumin in the retinas of eyes with experimental glaucoma may serve to protect the retina against oxidative damage.