Identification of TP53BP2 as a Novel Candidate Gene for Primary Open Angle Glaucoma by Whole Exome Sequencing in a Large Multiplex Family.

Primary open angle glaucoma (POAG) is a major type of glaucoma characterized by progressive loss of retinal ganglion cells with associated visual field loss without an identifiable secondary cause. Genetic factors are considered to be major contributors to the pathogenesis of glaucoma. The aim of the study was to identify the causative gene in a large family with POAG by applying whole exome sequencing (WES). WES was performed on the DNA of four affected family members. Rare pathogenic variants shared among the affected individuals were filtered. Polymerase chain reaction and Sanger sequencing were used to analyze variants segregating with the disease in additional family members. WES analysis identified a variant in TP53BP2 (c.109G>A; p.Val37Met) that segregated heterozygously with the disease. In silico analysis of the substitution predicted it to be pathogenic. The variant was absent in public databases and in 180 population-matched controls. A novel genetic variant in the TP53BP2 gene was identified in a family with POAG. Interestingly, it has previously been demonstrated that the gene regulates apoptosis in retinal ganglion cells. This supports that the TP53BP2 variant may represent the cause of POAG in this family. Additional screening of the gene in patients with POAG from different populations is required to confirm its involvement in the disease.

Variants in the PRPF8 Gene are Associated with Glaucoma.

Glaucoma is the cause of irreversible blindness worldwide. Mutations in six genes have been associated with juvenile- and adult-onset familial primary open angle glaucoma (POAG) prior to this report but they explain only a small proportion of the genetic load. The aim of the study is to identify the novel genetic cause of the POAG in the families with adult-onset glaucoma. Whole exome sequencing (WES) was performed on DNA of two affected individuals, and predicted pathogenic variants were evaluated for segregation in four affected and three unaffected Dutch family members by Sanger sequencing. We identified a pathogenic variant (p.Val956Gly) in the PRPF8 gene, which segregates with the disease in Dutch family. Targeted Sanger sequencing of PRPF8 in a panel of 40 POAG families (18 Pakistani and 22 Dutch) revealed two additional nonsynonymous variants (p.Pro13Leu and p.Met25Thr), which segregate with the disease in two other Pakistani families. Both variants were then analyzed in a case-control cohort consisting of Pakistani 320 POAG cases and 250 matched controls. The p.Pro13Leu and p.Met25Thr variants were identified in 14 and 20 cases, respectively, while they were not detected in controls (p values 0.0004 and 0.0001, respectively). Previously, PRPF8 mutations have been associated with autosomal dominant retinitis pigmentosa (RP). The PRPF8 variants associated with POAG are located at the N-terminus, while all RP-associated mutations cluster at the C-terminus, dictating a clear genotype-phenotype correlation.

Analyses of Sequence Variants in the MYOC Gene and of Single Nucleotide Polymorphisms in the NR3C1 and FKBP5 Genes in Corticosteroid-Induced Ocular Hypertension.

BACKGROUND: To perform an independent replication study to determine whether genetic variants in MYOC, NR3C1 and FKBP5 are involved in steroid-induced ocular hypertension. MATERIALS AND METHODS: A retrospective case-control study was peformed on native Dutch patients who were treated with 4.0 mg intravitreal triamcinolone acetonide (IVTA). The patients were divided into an intraocular hypertension group (intraocular pressure >21 mmHg within a year after IVTA) and a non-intraocular hypertension group. The cohort was genotyped for 31 single-nucleotide polymorphisms (SNPs): 21 in NR3C1 and 10 in FKBP5. In addition, the open reading frame of MYOC was sequenced. RESULTS: A total of 102 patients were included in this study: 58 steroid responders and 44 non-responders. No significant associations were found for the studied SNPs in NR3C1 and FKBP5. Heterozygous amino acid variants were detected in the MYOC gene in two patients of the non-intraocular hypertension group. CONCLUSIONS: This study does not confirm a role for genetic variants in the MYOC, NR3C1 and FKBP5 genes in the pathogenesis of corticosteroid-induced ocular hypertension.

The ocular disease of Aristodemus and Eurytus 480 BC: diagnostic considerations.

OBJECTIVE: In the historic description of Herodotus on the battle of Thermopylae at 480 BC two formerly healthy warriors suffer from "ophthalmia". The purpose of this study is to assess the possible aetiologies of this disease. DESIGN: We studied Herodotus' description in translation and offer a differential diagnosis. RESULTS: From the text we deduced that the "ophthalmia" was a condition in two physically fit males with a bilateral decreased or distorted vision, lasting longer than an hour, with an acute or subacute onset in Ancient Greece. The condition ultimately went into remission in one of the two patients, whereas the other subject deceased in combat not long after the onset of the disease, still suffering from the disease. The differential diagnosis consists of (1) anticholinergic syndrome secondary to an intoxication with the berries of the plant Atropa belladonna, (2) automutilation and (3) psychogenic loss of visual acuity. CONCLUSION: It is impossible to assess the ultimate cause of the "opthalmia" after 2500 years, but we suggest the anticholinergic syndrome by intoxication with Atropa belladonna is the most likely.

Analysis of single nucleotide polymorphisms in the SFRS3 and FKBP4 genes in corticosteroid-induced ocular hypertension.

BACKGROUND: The use of intravitreal triamcinolone acetonide (IVTA) can cause ocular hypertension. This steroid response appears to be heritable and alleles in the SFRS3 and FKBP4 genes have recently been suggested to play a role. The purpose of the present study was to perform an independent replication study to determine whether single nucleotide polymorphisms (SNPs) in SFRS3 and FKBP4 are involved in the steroid response. MATERIALS AND METHODS: A retrospective case-control study of native Dutch patients was performed who were treated with 4.0mg IVTA. The patients were divided into an intraocular hypertension group (intraocular pressure > 21 mmHg within a year after IVTA) and a non-intraocular hypertension group. The cohort was genotyped for three SNPs: rs7759778 and rs1406945 in SFRS3, and rs2968909 in FKBP4. RESULTS: A total of 102 patients was included: 58 steroid responders and 44 non-responders. No significant differences in demographic parameters or medical history were observed between the study groups. None of the SNPs were found to be significantly associated with the disease as no difference was revealed either in the genotype or allele frequencies between responders and non-responders. CONCLUSIONS: This study does not confirm a role for genetic variants in the SFRS3 and FKBP4 genes in the pathogenesis of corticosteroid-induced ocular hypertension. However, our limited sample size may have restricted the power of our study, and we therefore cannot exclude the involvement of these genetic variants in steroid response.

Autosomal dominant optic neuropathy and sensorineual hearing loss associated with a novel mutation of WFS1.

PURPOSE: To describe the phenotype of a novel Wolframin (WFS1) mutation in a family with autosomal dominant optic neuropathy and deafness. The study is designed as a retrospective observational case series. METHODS: Seven members of a Dutch family underwent ophthalmological, otological, and genetical examinations in one institution. Fasting serum glucose was assessed in the affected family members. RESULTS: All affected individuals showed loss of neuroretinal rim of the optic nerve at fundoscopy with enlarged blind spots at perimetry. They showed a red-green color vision defect at color vision tests and deviations at visually evoked response tests. The audiograms of the affected individuals showed hearing loss and were relatively flat. The unaffected individuals showed no visual deviations or hearing impairment. The affected family members had no glucose intolerance. Leber hereditary optic neuropathy (LHON) mitochondrial mutations and mutations in the Optic atrophy-1 gene (OPA1) were excluded. In the affected individuals, a novel missense mutation c.2508G>C (p.Lys836Asn) in exon 8 of WFS1 was identified. CONCLUSIONS: This study describes the phenotype of a family with autosomal dominant optic neuropathy and hearing impairment associated with a novel missense mutation in WFS1.

Variable clinical spectrum of the myocilin Gln368X mutation in a Dutch family with primary open angle glaucoma.

PURPOSE: To describe the clinical phenotype in a family with primary open angle glaucoma harboring a p.Gln368X mutation in MYOC. MATERIALS AND METHODS: We identified a proband with primary open angle glaucoma and the p.Gln368X MYOC mutation. She and her six siblings were examined clinically, including Heidelberg Retina Tomography II, and venous blood samples were screened for other variants in MYOC, WDR36, OPTN, and CYP1B1. RESULTS: Four individuals showed the p.Gln368X MYOC mutation, no other genetic variations were assessed. Two of these four siblings had glaucomatous optic disc changes with corresponding visual field losses and abnormal Heidelberg Retina Tomography results by the Moorfields regression analysis, one had abnormal results by the Moorfields regression analysis but no visual field loss, and one showed no glaucomatous signs or symptoms at all. These findings did not correlate with the age of the affected individuals. CONCLUSION: In the primary open angle glaucoma family described here, we documented a wide range in clinical symptoms, demonstrating a highly variable penetrance of the MYOC p.Gln368X mutation.

Identification and functional characterization of a novel MYOC mutation in two primary open angle glaucoma families from The Netherlands.

PURPOSE: Glaucoma is the second most prevalent cause of blindness worldwide, projected to affect more than 60 million people by 2010, 75% of which represents primary open angle glaucoma (POAG). Of the three genes, namely, Myocilin (MYOC), Optineurin (OPTN), and WD repeat-containing protein 36 (WDR36), which have been shown to cause POAG when defective, MYOC is the most frequently mutated gene, accounting for 3%-4% of all POAG cases. The purpose of this study was identification and functional characterization of MYOC mutations in adult-onset, high-pressure POAG patients from The Netherlands. METHODS: The following criteria were required for study participants to be included: have at least two affected family members, an age of diagnosis of more than 35 years, intraocular pressure (IOP) of more than 22 mmHg, glaucomatous optic neuropathy in both eyes, visual field loss consistent with assessed optic neuropathy in at least one eye, and an open anterior chamber angle without morphological abnormalities by gonioscopy. Sequence analysis was performed in genomic DNA of 30 probands for the protein coding region of the MYOC gene. A Chinese hamster ovarian cell line (CHO-K1) was used to express wild type and mutant MYOC protein. Detergent solubility of MYOC was assayed and its secretory property was analyzed by immunoprecipitation. RESULTS: We recruited 250 individuals from 30 families (120 affected and 130 unaffected family members) with a positive history of POAG. We identified a novel mutation c.1288T>C (p.Phe430Leu) in exon 3 of MYOC in two unrelated families showing the same haplotype around the mutant allele. The novel mutation segregated completely with the disease in these families and was absent in 250 ethnically matched controls. All patients harboring this mutation showed severe glaucomatous damage, pointing to the deleterious effect of this mutation. Compared to the wild type, the mutant protein was less soluble when extracted with Triton X-100 and was secretion-defective. CONCLUSIONS: The novel MYOC mutation, p.Phe430Leu, has the same origin in both POAG families from The Netherlands. The pathogenic nature of this mutation is suggested by the severe phenotype of mutant patients and mistrafficking of mutant protein as observed for other severe disease-causing mutations of MYOC.