The inheritance of juvenile onset primary open angle glaucoma

Identification and structural analysis of pathogenic variants in MYOC and CYP1B1 genes in Indian JOAG patients

PURPOSE

Juvenile onset open-angle glaucoma (JOAG) manifests in individuals under the age of 40, resulting in elevated intraocular pressure and significant optic nerve damage. To broaden the spectrum of mutations associated with JOAG and to determine their specific structural implications, we examined Myocilin and Cytochrome P450 1B1 gene in a cohort of 111 unrelated North Indian patients diagnosed with JOAG.

STUDY DESIGN

A clinical and experimental study.

METHODS

PCR-DNA sequencing screened the coding exons and intron-exon junctions of the MYOC and CYP1B1 genes in 111 unrelated JOAG patients and 100 controls. Identified sequence variations were searched in the ClinVar database, HGMD, and dbSNP. Six different online available algorithms including rare exome variant ensemble learner (REVEL), Sorting Intolerant From Tolerant (SIFT), Mutation Taster, SNAP2, IMutant2.0, and MutPred2 were used for the pathogenicity prediction of missense variations. The Structural consequences of detected possible pathogenic variations were predicted by using PyMol, Chimera and MD simulation of these changes.

RESULTS

Potentially-pathogenic variations were observed in thirty patients (27.02%) within the MYOC and CYP1B1 genes, encompassing both novel and previously documented variants. Structural predictions of novel potentially-pathogenic mutations indicate altered stability and flexibility.

CONCLUSION

Analysis reveals a higher prevalence of CYP1B1 gene variants (22.5%) relative to MYOC gene variants (4.5%), suggesting that CYP1B1 is the predominant gene implicated in JOAG among Indian patients. Our findings enhance the understanding of mutation spectra and frequencies of MYOC and CYP1B1gene in JOAG among the North Indian population. Structural predictions of novel pathogenic mutations could enhance the understanding of JOAG pathogenesis and support subsequent functional analysis.

Outcomes of Second Trabeculectomy Versus Glaucoma Drainage Device in Juvenile Open Angle Glaucoma After Primary Trabeculectomy Failure

PRCIS

Second trabeculectomy and glaucoma drainage device implantation offer similar success rates for juvenile open angle glaucoma after initial trabeculectomy failure. However, second trabeculectomies required fewer medications. A quarter of patients in both groups required a third operation after 2.5±2.3 years.

PURPOSE

To compare outcomes between second trabeculectomy surgery versus glaucoma drainage device (GDD) insertion in juvenile open angle glaucoma (JOAG) patients after primary trabeculectomy failure.

METHOD

A retrospective review was performed on all JOAG patients who underwent a second glaucoma surgery after primary trabeculectomy failure across 2 tertiary hospitals in Bangkok, Thailand between 2009 and 2020. Demographics, intraoperative reports, and clinical findings were collected. The primary outcomes were complete and qualified success rates at 5 years; secondary outcomes included differences in intraocular pressures and a number of glaucoma medications postoperatively.

RESULTS

Fifty-two eyes of 38 patients underwent a second glaucoma surgery after primary trabeculectomy: 30 had a second trabeculectomy, 17 received a GDD (10 valved, 7 non-valved), and 5 underwent cyclophotocoagulation. Before surgery, there were no significant differences except in mean refractive error. The average follow-up length was 66.9±53.7 months. Qualified success rates were 81.5% and 63.2% at 3 and 5 years (complete success: 55.6% and 42.1%) for the second trabeculectomy group and 80.0% and 70.0% (complete success: 53.3% and 50.0%) for the GDD group, respectively. There were no significant differences in group success or IOP postoperatively. The GDD group required more medications at 5 years (1.3±1.9 vs. 2.3±1.5, P =0.03). Two cases of tube exposure in the GDD group resulted in implant removal. About a quarter of patients in both groups required a third operation after 2.5±2.3 years.

CONCLUSION

Both second trabeculectomy and GDD insertion are effective treatments for JOAG after trabeculectomy failure. The second trabeculectomy required fewer medications for intraocular pressure control.

A New Ocular Phenotype Combining Juvenile Glaucoma and Doyne Honeycomb Retinal Dystrophy (Malattia Leventinese) due to a Novel EFEMP1 Pathogenic Variant

Doyne honeycomb retinal dystrophy (DHRD), also termed malattia leventinese (MLVT), is a dominantly inherited ocular disease characterized by the progressive accumulation of macular and peripapillary drusenoid material beneath the retinal pigment epithelium in the Bruch membrane. In all affected individuals genetically characterized to date, DHRD/MLVT is caused by a single heterozygous p.Arg345Trp missense variant in the EGF-containing fibulin-like extracellular matrix protein 1, EFEMP1. Recently, pathogenic variants in the EFEMP1 gene have also been demonstrated in several families with juvenile or adult-onset hereditary isolated glaucoma. Here, we describe a family featuring a unique phenotype of juvenile glaucoma and DHRD/MLVT caused by a novel EFEMP1 variant. Our results expand both the ocular phenotype associated with EFEMP1 variants and the molecular spectrum causing DHRD by describing the first non-p.Arg345Trp EFEMP1 pathogenic allele.

Exploring the Genetic Landscape of Childhood Glaucoma

Childhood glaucoma, a significant cause of global blindness, represents a heterogeneous group of disorders categorized into primary or secondary forms. Primary childhood glaucoma stands as the most prevalent subtype, comprising primary congenital glaucoma (PCG) and juvenile open-angle glaucoma (JOAG). Presently, multiple genes are implicated in inherited forms of primary childhood glaucoma. This comprehensive review delves into genetic investigations into primary childhood glaucoma, with a focus on identifying causative genes, understanding their inheritance patterns, exploring essential biological pathways in disease pathogenesis, and utilizing animal models to study these mechanisms. Specifically, attention is directed towards genes such as CYP1B1 (cytochrome P450 family 1 subfamily B member 1), LTBP2 (latent transforming growth factor beta binding protein 2), TEK (TEK receptor tyrosine kinase), ANGPT1 (angiopoietin 1), and FOXC1 (forkhead box C1), all associated with PCG; and MYOC (myocilin), associated with JOAG. Through exploring these genetic factors, this review aims to deepen our understanding of the intricate pathogenesis of primary childhood glaucoma, thereby facilitating the development of enhanced diagnostic and therapeutic strategies.

Genetics and Glaucoma: the state of the art

Glaucoma is the second leading cause of irreversible blindness worldwide. Although genetic background contributes differently to rare early-onset glaucoma (before age 40) or common adult-onset glaucoma, it is now considered an important factor in all major forms of the disease. Genetic and genomic studies, including GWAS, are contributing to identifying novel loci associated with glaucoma or to endophenotypes across ancestries to enrich the knowledge about glaucoma genetic susceptibility. Moreover, new high-throughput functional genomics contributes to defining the relevance of genetic results in the biological pathways and processes involved in glaucoma pathogenesis. Such studies are expected to advance significantly our understanding of glaucoma's genetic basis and provide new druggable targets to treat glaucoma. This review gives an overview of the role of genetics in the pathogenesis or risk of glaucoma.

A novel heterozygous c.733 T > G MYOC mutation associated with juvenile-onset open-angle glaucoma in a Chinese family

AIMS

To detect mutations in juvenile-onset open-angle glaucoma in a Chinese family and to describe the characteristic ophthalmic phenotypes of this pedigree.

METHODS

There were 14 individuals in this four-generation pedigree. All living members of the family underwent comprehensive ophthalmic examinations. Five patients presented with elevated intraocular pressures. All of them shared early-onset disease, with a mean onset age of 14.4 years and continuing aggressive damage to their optic nerves. Hyperpigmentation in the trabecular meshwork and sometimes-broad iris processes were noted in this family using gonioscopy. All exons of candidate genes (MYOC, OPTN, CYP1B1) were amplified using the polymerase chain reaction, and analysed with an ABI 3700XL Genetic Analyser.

RESULTS

A heterozygous missense mutation in exon 3 (c.733 T > G) of the MYOC gene was found in the five JOAG patients and one 7-year-old boy with no ophthalmic manifestation of glaucoma, but it was absent in other members of the family and in the controls. This mutation resulted in a transversion of cysteine to glycine (Cys245Gly).

CONCLUSIONS

We concluded the novel MYOC c.733 T > G mutation found in a Chinese family with JOAG caused a severe type of JOAG exhibiting early onset, high IOP, and severe optic nerve damage. Interestingly, unlike other reported MYOC mutation families, our patients exhibited marked angle pigmentation and iris processes.

Molecular genetics of primary open-angle glaucoma

Glaucoma is a series of linked optic diseases resulting in progressive vision loss and total blindness due to the acquired loss of retinal ganglion cells. This harm to the optic nerve results in visual impairment and, ultimately, total blindness if left untreated. Primary open-angle glaucoma (POAG) is the most frequent variety within the large family of glaucoma. It is a multifaceted and heterogeneous condition with several environmental and genetic variables aiding in its etiology. By 2040, there will be 111.8 million glaucoma patients globally, with Asia and Africa accounting for the vast majority. The goal of this review is to elaborate on the role of genes (nuclear and mitochondrial) as well as their variants in the pathogenesis of POAG. PubMed and Google Scholar databases were searched online for papers until September 2022. Prevalence and inheritance patterns vary significantly across different ethnic and geographic populations. Numerous causative genetic loci may exist; however, only a few have been recognized and characterized. Further investigation into the genetic etiology of POAG is expected to uncover novel and intriguing causal genes, allowing for a more precise pathogenesis pattern of the disease.

Extranuclear DNA Variations in the Susceptibility of Glaucoma

Glaucoma is a leading cause of irreversible blindness worldwide which affects all age groups. It is often identified by high intraocular pressure, characteristic optic neuropathy, and vision loss. Due to multifactorial nature of glaucoma pathogenesis, the molecular events responsible for its precipitation are currently poorly understood. Mitochondrial DNA (mtDNA) variations which are inherited maternally are being closely studied in recent times to elucidate the effect on glaucoma. Mitochondrial genetic studies till date have found a possible link between Leber hereditary optic neuropathy loci and glaucoma but with conflicting views. Furthermore, whole mtDNA studies in glaucoma points at the involvement of oxidative phosphorylation complex I and specifically the NADH dehydrogenase 5 gene in glaucoma. This review focuses on identifying the potential genes and variations in the maternally inherited mtDNA which might be involved in glaucoma pathogenesis.

A new association of PAX6 variation with Juvenile onset open angle glaucoma

Mutations in the PAX6 gene are generally associated with aniridia. We describe a family with Juvenile onset open angle glaucoma (JOAG), where one of the two children had JOAG and the other Juvenile ocular hypertension. Whole exome sequencing was performed for the parents and their two affected children where the proband and her sibling were detected to have a de novo PAX6 gene variant in the absence of aniridia. All previously described gene mutations for glaucoma were looked for in the family. The potential pathogenicity of the identified variants was assessed by determining their frequency in large public exome databases; as well as using the current ACMG guidelines. The same heterozygous variant at NM_000280.6:c.1124 C > A; p. Pro375Gln in the PAX6 gene was detected in the proband and her affected brother. The variant has been described in aniridia patients before and has been shown to cause a weaker DNA binding using functional studies. This report expands the phenotypic spectrum of the PAX6 gene to include Juvenile onset open angle glaucoma.

Cataract surgery and Hydrus stent implantation in juvenile open-angle glaucoma: A case report

PURPOSE

To report a case of a patient with juvenile-onset open-angle glaucoma (JOAG) who was successfully treated with combination cataract extraction and Hydrus stent implantation.

METHODS

An interventional case report.

RESULTS

The patient underwent cataract surgery and Hydrus stent implantation in the right eye. Preoperative intraocular pressure (IOP) was 25 mmHg in the right eye (OD) and 21 mmHg in the left eye (OS). Best-corrected visual acuities (BCVA) were 20/80 in the right eye and 20/200 in the left eye. Postoperatively, vision improved to 20/40 in the right eye with an IOP of 14 mmHg after 21 months follow up. No device-related complications were observed.

CONCLUSIONS

Cataract surgery in combination with the Hydrus stent implant effectively lowers intraocular pressures and can be used to surgically manage patients with JOAG. This intervention is a probable adjunct or substitute to first line treatments such as trabeculotomy.

Biallelic variants in CPAMD8 are associated with primary open-angle glaucoma and primary angle-closure glaucoma

BACKGROUND/AIMS

This study aims to assess the contribution of biallelic CPAMD8 variants in patients with different forms of glaucoma, especially primary open-angle glaucoma (POAG) and primary angle-closure glaucoma (PACG), based on a systematic analysis of exome sequencing (ES).

METHODS

Potentially pathogenic CPAMD8 variants were selected from the ES data of 5307 subjects with various eye conditions through multiple bioinformatics analyses. Of the 5307 subjects, 1221 probands had different forms of primary glaucoma. The genotype-phenotype correlation was assessed by a systematic review of biallelic CPAMD8 variants that including our data and data from the literature. The expression profile of CPAMD8 in human tissues was determined at the mRNA and protein levels.

RESULTS

Biallelic CPAMD8 variants, including one frameshift and six missense variants, were exclusively present and significantly enriched in patients with glaucoma (one with juvenile open-angle glaucoma (JOAG), two with POAG and two with PACG) compared with none of the 4086 probands with other eye conditions in this cohort (p=4.1E-07). The effect of variants in these patients is relatively mild compared with that reported in patients with anterior segment dysgenesis or primary congenital glaucoma. CPAMD8 mRNA was highly expressed in the optic nerve, ciliary body, retina and iris, whereas the CPAMD8 protein was mainly detected in the nonpigmented epithelium of the iris and ciliary process, determined by immunohistochemistry.

CONCLUSIONS

The data from this study not only provide further evidence to support the association of biallelic CPAMD8 variants with JOAG but also suggest that biallelic CPAMD8 variants might be associated with POAG and PACG.

Association of EFEMP1 with juvenile-onset open angle glaucoma in a patient with concomitant COL11A1-related Stickler syndrome

BACKGROUND

Juvenile onset open-angle glaucoma is described as a primary open-angle glaucoma, with an age of onset before 40 years. These patients have a higher prevalence of myopia.

PURPOSE

We describe the phenotype of juvenile onset open-angle glaucoma in a patient with a rare variant in EFEMP1 gene, who was also detected to have Stickler syndrome(STL).

METHODS

Whole exome sequencing (WES) was undertaken in 40 unrelated families where the proband had juvenile onset open-angle glaucoma (JOAG).

RESULTS

Out of these, eight were autosomal dominant, while the rest did not have any other affected first-degree relative. Out of the 8 autosomal dominant JOAG families, MYOC mutations were detected in 3(37.5%) and LTBP2 in 1(12.5%). One family (12.5%) had a rare EFEMP1 sequence variant in both affected father and daughter. The daughter also had high myopia and a pathogenic COL11A1 sequence variant that led to a coincidental diagnosis of STL in her.

CONCLUSIONS

This is a rare association of EFEMP1 and COL11A1 sequence variants in a JOAG patient with STL. The study also reiterates the association of JOAG with EFEMP1, which should be looked for, especially in families with autosomal dominant JOAG.

Juvenile-onset open-angle glaucoma - A clinical and genetic update

Juvenile-onset open-angle glaucoma (JOAG) is a subset of primary open-angle glaucoma that is diagnosed before 40 years of age. The disease may be familial or non-familial, with proportions varying among different populations. Myocilin mutations are the most commonly associated. JOAG is characterized by high intraocular pressures (IOP), with many patients needing surgery. The mean age at diagnosis is in the 3rd decade, with a male preponderance. Myopia is a common association. The pathophysiology underlying the disease is immaturity of the conventional outflow pathways, which may or may not be observed on gonioscopy and anterior segment optical coherence tomography. The unique optic nerve head features include large discs with deep, steep cupping associated with high IOP-induced damage. Progression rates among JOAG patients are comparable to adult primary glaucomas, but as the disease affects younger patients, the projected disability from this disease is higher. Early diagnosis, prompt management, and life-long monitoring play an important role in preventing disease progression. Gene-based therapies currently under investigation offer future hope.

Factors affecting the surgical success of trabeculectomy performed as the first surgery in primary pediatric glaucoma

PURPOSE

To present the outcomes and factors affecting the success of trabeculectomy performed as the first surgery in primary pediatric glaucoma.

METHODS

Pediatric patients with primary glaucoma who underwent trabeculectomy as the first surgery were retrospectively reviewed. Age, gender, preoperative intraocular pressure (IOP), operation age, axial length, corneal diameter, anterior segment findings, antimetabolite used, complications, and 1-month, 3-months, 1-year, and most recent postoperative findings were recorded. Postoperative IOP with/without medication of 18 mmHg or less was considered successful. Factors that may have affected surgical success were also evaluated using multivariate analysis.

RESULTS

Included in the study were 48 patients, of whom 30 had primary congenital glaucoma and 18 had juvenile glaucoma. The mean preoperative IOP was 36.84 ± 6.30 mmHg, and the mean follow-up time was 7.95 ± 6.93 years. The median operation age value was 100.00 ± 100.83 (median: 60; IQR: 153) months. The postoperative IOP at the 1-month, 3-months, 1-year, and most recent follow-ups were 15.39 ± 6.88, 15.70 ± 7.36, 16.28 ± 7.86, and 17.48 ± 8.44 mmHg, respectively (p = 0.565). While there were no postoperative complications in 24 of the patients (50.0%), the most common complications were choroidal detachment and hypotony. Postoperative complication development was found to be significant as a factor affecting surgical success in the multivariate logistic regression analysis. Surgical success rates for all of the patients were 71.7%, 65.9%, 65.0%, and 61.4% at the 1-month, 3-months, 1-year, and most recent follow-ups, respectively. A significant difference was found between the congenital and juvenile groups in terms of surgical success only at 3 months (p = 0.953, p = 0.042, p = 0.191, p = 0.218; respectively).

DISCUSSION/CONCLUSION

The fact that surgical success was partially higher in the juvenile group confirmed the idea that the results of trabeculectomy will be more favorable in patients of older age and without anterior segment anomalies.

Identification of proteomic changes for dexamethasone-induced ocular hypertension using a tandem mass tag (TMT) approach

Glaucoma, characterized by ocular hypertension, is the second most common cause of vision loss worldwide. The potential mechanism, however, has yet to be elucidated. This study aimed to assess the proteomic changes in the trabecular meshwork (TM) in an observational animal model of Dexamethasone (DEX)-induced OHT. OHT was induced in Wistar rats by applying DEX topically to both eyes for 28 days. Intraocular pressure (IOP) was evaluated and TM protein expressions and protein identification were performed by a TMT-based method for comparing the changes in proteins between DEX-induced OHT and the control group. The results showed that average IOP was elevated significantly in rats of the DEX-induced OHT group compared to controls. Further, a total of 4,804 proteins in the control and DEX-induced OHT group were determined and 4,064 proteins were quantified via TMT proteomics. In total, 292 significantly abundant proteins (173 downregulated and 119 upregulated) were identified between the two groups. Proteins associated with vision, including Crystallin related proteins, filensin, rhodopsin, recoverin, phosducin were lowered in the DEX-induced OHT group relative to the control group. In summary, DEX induced extensive changes in the protein expression of TM tissue. These proteins were found to be candidate biomarkers for personalized treatment and diagnostic research in the future for improving visual health.

Ahmed and Baerveldt Drainage Implants in the Treatment of Juvenile Open-angle Glaucoma

PRECIS

Ahmed and Baerveldt implants succeed in 90.7% of cases for lowering intraocular pressure (IOP) <21 mm Hg at 1 year when used for the treatment of juvenile open-angle glaucoma.

PURPOSE

The purpose of this study was to report the 1-year outcomes of Ahmed and Baerveldt tubes as the treatment for juvenile open-angle glaucoma at an academic institution.

PATIENTS AND METHODS

Patients 18 to 40 years of age at the time of juvenile open-angle glaucoma diagnosis, who had inadequately controlled glaucoma with an IOP of 18 mm Hg or more on maximum tolerated antiglaucoma therapy that underwent tube shunt surgery with at least 6 months of follow-up were eligible for the study. Exclusion criteria included evidence of neovascular, uveitic or inflammatory, steroid-induced or primary congenital glaucoma, or if they did not have light perception vision. Postoperative failure was defined as an IOP, with or without antiglaucoma drops, >21 mm Hg for 2 consecutive visits after 3 months from surgery, <20% decrease in IOP at 1 year, no light perception, or revision of an implant due to high IOP.

RESULTS

The study population included 32 eyes from 25 patients who underwent tube shunt surgery. The failure rate at 1-year follow-up was 9.3%, and the postoperative complication rate at 1-year follow-up was 9.3%. The average change from baseline to 1 year for IOP was a decrease of 9.8±9.10, for the number of antiglaucoma drops number was a decrease of 0.38±1.06, and for the visual acuity was an increase of 0.03±0.27.

CONCLUSIONS

Ahmed and Baerveldt implantation succeeded in lower IOP in 90.7% of patients at 1 year. Continuation of antiglaucoma drops to maintain the IOP after surgery is likely required.

Digenic Inheritance in Juvenile Open-Angle Glaucoma

Juvenile open-angle glaucoma (JOAG) is an uncommon subset of primary glaucoma with an onset before the age of 40 years. In this case report, we describe the cosegregation of MYOC, p.Pro370Leu and LTBP2, p.Pro432Leu mutations in a family with JOAG. The family with autosomal dominant JOAG belonged to Northern India. The samples of proband and her parents were evaluated by whole exome sequencing. Sanger sequencing was conducted in all the study participants to check the mutations identified. Both MYOC and LTBP2 mutations were found to cosegregate in affected individuals leading to a severe JOAG phenotype, thereby suggesting a digenic inheritance of MYOC with LTBP2 in this family.

Clinical and genetic analysis of Ser341Pro MYOC variant in a Korean family with primary open angle glaucoma

AIM

To report the first discovery of Ser341Pro myocilin (MYOC) variant in Korea and analyze its clinical characteristics and genetic significance.

METHODS

Ten family members from three generations participated in this study and received the thorough ophthalmologic examination. Focused exome sequencing on a proband was performed to confirm the target mutations (MYOC c.1021T>C) in the family members, and the direct sequencing was conducted. Variant was analyzed according to the American College of Medical Genetics and Genomics and the Association for Molecular Pathology (ACMG/AMP) guidelines.

RESULTS

A nucleotide change from thymine to cytosine at c.1021T>C was found in eight family members. Three members diagnosed with primary open angle glaucoma (POAG) were characterized by severe clinical presentations, high intraocular pressure, and poor response to medical treatment (100% of the patient required filtering surgery). On variant analysis by ACMG/AMP guidelines, Ser341Pro is not found in normal population. Multiple computational predictive programs support a deleterious effect of Ser341Pro variant (PolyPhen 2, SIFT, Mutation Taster). Ser341Pro could be involved in moderate (PM) and supporting (PP) criteria (PM1, PM2, PP2, PP3). Combining the criteria, Ser341Pro has a combination of 2 moderate (PM1+PM2) and 2 supporting (PP2+PP3) criteria, which is interpreted to "likely pathogenic".

CONCLUSION

The Ser341Pro variant is correlated with severe phenotype of POAG. There are similar clinical aspects to previous studies: autosomal dominant inheritance, incomplete penetrance (62.50% and 66.67%), and proportion of patients requiring trabeculectomy (100% in both study). According to ACMG/AMP guidelines and the previous basic researches, the Ser341Pro variant had a "strong evidence of pathogenicity (PS3)" and then it could be interpreted to "pathogenic (PS3, PM1, PM2, PP2, PP3)". Additionally, Ser341Pro variant can be reported as "c.1021T>C (p.Ser341Pro), likely pathogenic, POAG, autosomal dominant" according to guideline.

The Genetic and Endoplasmic Reticulum-Mediated Molecular Mechanisms of Primary Open-Angle Glaucoma

Glaucoma is a heterogenous, chronic, progressive group of eye diseases, which results in irreversible loss of vision. There are several types of glaucoma, whereas the primary open-angle glaucoma (POAG) constitutes the most common type of glaucoma, accounting for three-quarters of all glaucoma cases. The pathological mechanisms leading to POAG pathogenesis are multifactorial and still poorly understood, but it is commonly known that significantly elevated intraocular pressure (IOP) plays a crucial role in POAG pathogenesis. Besides, genetic predisposition and aggregation of abrogated proteins within the endoplasmic reticulum (ER) lumen and subsequent activation of the protein kinase RNA-like endoplasmic reticulum kinase (PERK)-dependent unfolded protein response (UPR) signaling pathway may also constitute important factors for POAG pathogenesis at the molecular level. Glaucoma is commonly known as a ‘silent thief of sight’, as it remains asymptomatic until later stages, and thus its diagnosis is frequently delayed. Thereby, detailed knowledge about the glaucoma pathophysiology is necessary to develop both biochemical and genetic tests to improve its early diagnosis as well as develop a novel, ground-breaking treatment strategy, as currently used medical therapies against glaucoma are limited and may evoke numerous adverse side-effects in patients.

The mutational spectrum of Myocilin gene among familial versus sporadic cases of Juvenile onset open angle glaucoma

PURPOSE

Juvenile onset primary open angle glaucoma (JOAG) is a rare disorder associated with high IOP and progressive optic neuropathy in patients diagnosed before the age of 40 years. While in some populations it has primarily an autosomal dominant pattern of inheritance, in others it occurs in a primarily sporadic form. The main aim of the study was to assess the relative prevalence of Myocilin (MYOC) mutations in familial versus sporadic cases of JOAG.

METHODS

We screened 92 unrelated (sporadic) JOAG patients, and 22 affected families (70 affected members and 36 unaffected) for variations in the MYOC gene. We also analyzed the clinical features associated with these variations.

RESULTS

Three coding sequence variants were identified as mutations causing JOAG. Four families segregated distinct mutations at Gly367Arg, and two families at Gln337Arg, while only two sporadic JOAG cases harbored MYOC mutations (Gly367Arg and Gln48His). The frequency of MYOC mutations in familial cases (27%) was significantly higher than in sporadic JOAG cases (2%); p = 0.001. A 90% penetrance for the Gly367Arg variant was seen by the age of 40 years in our patients. Characteristic allele signatures, indicative of specific founder effects, were not observed for the Gly367Arg mutation that was looked for in 12 patients among 2 geographically close families, which harbored this mutation.

CONCLUSION

Our data demonstrated that genetic screening for MYOC mutations should be focused toward cases with familial rather than sporadically occurring JOAG.

Classifying juvenile onset primary open angle glaucoma using cluster analysis

Aim

To classify unrelated patients with juvenile onset primary open angle glaucoma (JOAG) into clinically useful phenotypes using cluster analysis.

Methods

Out of the 527 unrelated patients with JOAG, the study included 414 patients who had all the phenotypic characteristics required for the study. A cluster analysis was performed to classify the patients based on their iris and angle morphology, age of onset, highest untreated intraocular pressure (IOP), worst mean deviation and greatest vertical cup disc ratio of the worst eye. The iris features were broadly classified into three groups: those with normal iris crypts (NIC), those with prominent iris crypts (PIC) and those with absence of iris crypts. The gonio photographs were graded as normal appearing angle or those with angle dysgenesis in the form of a featureless angle, one with a high iris insertion and an angle with prominent iris processes. Using a hierarchical clustering model and a two-way cluster analysis, the distribution of clusters of JOAG was analysed to obtain a classification of JOAG subtypes.

Results

The four major clusters identified were: Cluster 1 with NIC and normal angles had the lowest untreated IOP and higher age of onset among all clusters. Cluster 2 with NIC and featureless angle was found to be associated with earliest age of onset. Cluster 3 had NIC and either a high iris insertion or prominent iris processes. Cluster 4 was a heterogeneous cluster with maximum number of patients in a group comprising of those with PIC and high iris insertion.

Conclusions

Cluster analysis extracted four subgroups of the JOAG phenotype that have clinical and prognostic significance and can potentially be helpful while evaluating these patients in the clinics.

Therapeutic efficacy of latanoprost on primary open angle glaucoma: A protocol for a systematic review of randomized controlled trial

BACKGROUND

Latanoprost is quiet new formulation that is approved for the treatment of primary open angle glaucoma (POAG). However, no updated systematic review has addressed its efficacy for POAG. This systematic review of randomized controlled trials (RCTs) aims to assess its efficacy and safety for the treatment of patients with POAG.

METHODS

This study will search the databases of CENTRAL, EMBASE, MEDILINE, CINAHL, AMED and Chinese databases without language restrictions from their inception to the present. It will only include RCTs of latanoprost for POAG. The quality of the included RCTs will be evaluated by the tool of Cochrane risk of bias. The primary outcomes will be measured by the mean IOP reduction from baseline to the endpoint. The secondary outcomes will be assessed by the mean IOP, adjusted mean IOP reduction at each time point, quality of life, and adverse events. The RevMan V.5.3 software will be used to compute the data synthesis carefully if the meta-analysis is allowed. The summary results of the included RCTs will be conducted by using the models of random-effects or fixed-effects based.

RESULTS

The results of this study will be published at the peer-reviewed journals. It will provide evidence to determine the efficacy and safety of latanoprost for POAG.

CONCLUSION

The results of this study will provide helpful evidence for both clinicians and patients, and for the health policy makers to refer for the policy or guideline making.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO CRD42018115416.

Physiological function of myocilin and its role in the pathogenesis of glaucoma in the trabecular meshwork (Review)

Myocilin is highly expressed in the trabecular meshwork (TM), which plays an important role in the regulation of intraocular pressure (IOP). Myocilin abnormalities may cause dysfunction of the TM, potentially leading to increased IOP. High IOP is a well‑known primary risk factor for glaucoma. Myocilin mutations are common among glaucoma patients, and they are implicated in juvenile‑onset open‑angle glaucoma (JOAG) and adult‑onset primary open‑angle glaucoma (POAG). Aggregation of aberrant mutant myocilins is closely associated with glaucoma pathogenesis. The aim of the present review was to discuss the recent findings regarding the major physiological functions of myocilin, such as intra‑ and extracellular proteolytic processes. We also aimed to discuss the risk factors associated with myocilin and the development of glaucoma, such as misfolded/mutant myocilin, imbalance of myocilin and extracellular proteins, and instability of mutant myocilin associated with temperature. Finally, we further outlined certain issues that are yet to be resolved, which may represent the basis for future studies on the role of myocilin in glaucoma.

Delineation of Novel Compound Heterozygous Variants in LTBP2 Associated with Juvenile Open Angle Glaucoma

Juvenile open angle glaucoma (JOAG), which is an uncommon form of primary open angle glaucoma, is a clinically and genetically heterogeneous disorder. We report on a family with a recessively inherited form of JOAG. The proband has a superior and an inferior never fiber layer thinning in both the eyes and the nasal visual field (VF) defects in the left eye, which are clinical findings consistent with glaucomatous optic neuropathy. Whole exome sequencing revealed two novel compound heterozygous variants [c.2966C>G, p.(Pro989Arg); c.5235T>G, p.(Asn1745Lys)] in latent transforming growth factor-beta-binding protein 2 (LTBP2) segregating with the phenotype. Both these variants are predicted to replace evolutionary conserved amino acids, have a pathogenic effect on the encode protein, and have very low frequencies in the control databases. Mutations in LTBP2 are known to cause the Weill-Marchesani syndrome and a Weill-Marchesani-like syndrome, which include glaucoma in their clinical presentation. However, to our knowledge, this is the first published case of a JOAG subject associated with recessively inherited variants of LTPB2 and, thus, expands the repertoire of the known genetic causes of JOAG and the phenotypic spectrum of LTBP2 alleles.

Role of CYP1B1, p.E229K and p.R368H mutations among 120 families with sporadic juvenile onset open-angle glaucoma

BACKGROUND

To determine the frequency of CYP1B1 p.E229K and p.R368H, gene mutations in a cohort of sporadic juvenile onset open-angle glaucoma (JOAG) patients and to evaluate their genotype/phenotype correlation.

METHODS

Unrelated JOAG patients whose first-degree relatives had been examined and found to be unaffected were included in the study. The patients and their parents were screened for p.E229K and p.R368H mutations. The phenotypic characteristics were compared between probands carrying the mutations and those who did not carry these mutations.

RESULTS

Out of 120 JOAG patients included in the study, the p.E229K mutation was seen in 9 probands (7.5%) and p.R368H in 7 (5.8%). The average age of onset of the disease (p = 0.3) and the highest untreated IOP (p = 0.4) among those carrying mutations was not significantly different from those who did not have these mutations. The proportion of probands with angle dysgenesis among those with p.E229K and p.R368H mutations was 70% (11 out of 16) in comparison to 65% (67 out of 104) of those who did not harbour these mutations (p = 0.56). Similarly, the probands with moderate to high myopia among those with p.E229K and p.R368H mutations was 20% (3 out of 16) in comparison to 18% (18 out of 104) of those who did not harbour these mutations (p = 0.59).

CONCLUSION

The frequency of p.E229K and p.R368H mutations of the CYP1B1 gene is low even among sporadic JOAG patients. Moreover, there is no clinical correlation between the presence of these mutations and disease severity.

Phenotypic differences between familial versus non-familial Juvenile onset open angle glaucoma patients

AIM

To evaluate phenotypic differences among familial and non-familial JOAG patients.

METHODS

First degree relatives of unrelated JOAG patients were screened for glaucoma and ocular hypertension. JOAG probands were grouped as familial or non-familial and phenotypic differences in terms of age of onset, gender, baseline untreated IOP, presence angle dysgenesis, and refractive error was compared between the two groups.

RESULTS

Out of 368 unrelated JOAG patients, 134 in whom all first degree relatives had been examined were included in the study. The non-familial JOAG (n = 96) had similar age of onset as familial JOAG (n = 38); (p = 0.076) but had greater male preponderance (p = 0.046), and had the higher baseline IOP (p = 0.044) compared to familial JOAG. However, on adjustment using the Bonferroni correction, the observed differences were not found to be significant. Both groups had similar proportion of patients with angle dysgenesis (p = 0.46) and high myopia (p = 0.72).

CONCLUSIONS

Non-familial JOAG were not found to be phenotypically different from the familial JOAG patients in this cohort.