PRIMARY OPEN-ANGLE GLAUCOMA DUE TO MUTATIONS IN THE MYOC GENE.

AIM: Mutations in the myocilin gene (MYOC) cause trabecular dysfunction and thus are involved in the pathogenesis of primary open-angle glaucoma (POAG). The aim of this study was to characterize and describe the clinical findings in two Czech families with POAG due to pathogenic variants in the MYOC gene. MATERIAL AND METHODS: Members of the two families affected by POAG underwent complete ophthalmological examination. In the proband from the first family, a direct sequencing of the three most frequent mutations in the MYOC gene was performed, and in the proband from the second family, an exome sequencing was performed. Other family members underwent targeted tests using direct sequencing. RESULTS: In total, 10 individuals diagnosed with POAG aged 20-70 years (mean 32.2 years, SD ±10,9 years) were examined. Eight of them showed advanced glaucomatous neuropathy with severe changes in the retinal nerve fiber layer. Clinical signs of POAG were present in six individuals in the third decade of life already; another four developed POAG during the fourth decade of life. Eight out of 10 patients had to undergo filtration surgery. Surgery was performed within 1 to 7 years of diagnosis, but mostly was performed within 2 years of glaucoma diagnosis. In the first family, MYOC variant c.1099G>A p.(Gly367Arg) was shown in the affected family members; in the second family MYOC variant c.1440C>A p.(Asn480Lys), both in heterozygous state. The changes were assessed as pathogenic. CONCLUSION: Our study is the first to describe mutations in the MYOC gene causing POAG in Czech patients. Genetic testing may be recommended for this diagnosis, especially in individuals with early presentation and a positive family history. Carriers of pathogenic variants of the MYOC gene have a lifetime risk of developing POAG of more than 50% and the course of their disease is often more aggressive, requiring surgical intervention to permanently control the intraocular pressure.

Phenotype Variability in Czech Patients Carrying PAX6 Disease-Causing Variants.

The aim of this study was to report PAX6 disease-causing variants in six Czech families, to describe the associated phenotypes, and to perform functional assessment of the splice site variants. Detailed ophthalmic examination was performed. The PAX6 coding region was directly sequenced in three probands. Two probands were analysed by exome sequencing and one by genome sequencing. The effect of two variants on pre-mRNA splicing was evaluated using an exon trapping assay. Six different heterozygous PAX6 variants were identified, with c.111_120del and c.1183+1G˃T being novel. Both c.1183+1G˃T and c.1032+1G>A were proved to cause aberrant splicing with exon skipping and subsequent frameshift. The phenotypic features were variable between and within families. One individual, aged 31 years, presented with mild unilateral ptosis accompanied by aniridia in the right eye, partial aniridia in the left eye, and bilateral congenital cataracts, without marked foveal hypoplasia. Bilateral microcornea, partial aniridia, congenital cataracts, and a large posterior segment coloboma were found in another proband, aged 32 years. One child, aged 8 years, had bilateral high myopia, optic nerve colobomas, anterior polar cataracts, but no iris defects. Another individual, aged 46 years, had bilateral congenital ptosis, iris hypoplasia, keratopathy with marked fibrovascular pannus, anterior polar cataract, and foveal hypoplasia combined with impaired glucose tolerance. However, his daughter, aged 11 years, showed classical features of aniridia. Our study extends the genetic spectrum of PAX6 disease-causing variants and confirms that the associated phenotypic features may be very broad and different to the 'classical' aniridia.

Review of SRD5A3 Disease-Causing Sequence Variants and Ocular Findings in Steroid 5α-Reductase Type 3 Congenital Disorder of Glycosylation, and a Detailed New Case.

Steroid 5α-reductase type 3 congenital disorder of glycosylation (SRD5A3-CDG) is a severe metabolic disease manifesting as muscle hypotonia, developmental delay, cerebellar ataxia and ocular symptoms; typically, nystagmus and optic disc pallor. Recently, early onset retinal dystrophy has been reported as an additional feature. In this study, we summarize ocular phenotypes and SRD5A3 variants reported to be associated with SRD5A3-CDG. We also describe in detail the ophthalmic findings in a 12-year-old Czech child harbouring a novel homozygous variant, c.436G>A, p.(Glu146Lys) in SRD5A3. The patient was reviewed for congenital nystagmus and bilateral optic neuropathy diagnosed at 13 months of age. Examination by spectral domain optical coherence tomography and fundus autofluorescence imaging showed clear signs of retinal dystrophy not recognized until our investigation. Best corrected visual acuity was decreased to 0.15 and 0.16 in the right and left eye, respectively, with a myopic refractive error of -3.0 dioptre sphere (DS) / -2.5 dioptre cylinder (DC) in the right and -3.0 DS / -3.0 DC in the left eye. The proband also had optic head nerve drusen, which have not been previously observed in this syndrome.

Molecular genetic cause of achromatopsia in two patients of Czech origin.

INTRODUCTION: Achromatopsia is an autosomal recessive retinal disorder with an estimated prevalence ranging from 1 in 30.000 to 50.000. The disease is caused by mutations in six different genes. The aim of the study was to perform molecular genetic analysis in 11 unrelated probands with a clinical diagnosis of achromatopsia and to describe clinical findings in those that were found to carry biallelic pathogenic mutations. METHODS: All probands and their parents underwent ophthalmic examination. Mutation detection was performed using Sanger sequencing of CNGB3 exons 6, 7, 9-13, which have been found to harbour most disease-causing mutations in patients with achromatopsia of European origin. RESULTS: Three known pathogenic variants in CNGB3 were identified in 2 probands. Proband 1 was a compound heterozygote for the c.819_826del; p.(Arg274Valfs*13) and c.1006G>T; p.(Glu336*). Proband 2 carried the c.1148del; p.(Thr383Ilefs*13) in a homozygous state. The best corrected visual acuity in proband 1 (aged 19 years) was 0.1 in both eyes, in proband 2 (aged 8 years) 0.05 in the right eye and 0.1 in the left eye. Both individuals had nystagmus, photophobia, and absence of colour discrimination. Fundus examination appeared normal however spectral-domain optical coherence tomography revealed subtle bilaterally symmetrical structural changes in the fovea. CONCLUSION: Molecular genetic analysis of Czech patients with achromatopsia was performed for the first time. Identification of disease-causing mutations in achromatopsia is important for establishing an early diagnosis, participation in clinical trials assessing gene therapies and may be also used for preimplantation genetic diagnosis.

[Gene Therapy for Inherited RETINAL AND OPTIC NERVE Disorders: Current Knowledge]. / Genová terapie dedicných onemocnení SÍTNICE A ZRAKOVÉHO NERVU: soucasný stav poznání.

The aim of this review is to provide a comprehensive summary of current gene therapy clinical trials for monogenic and optic nerve disorders.The number of genes for which gene-based therapies are being developed is growing. At the time of writing this review gene-based clinical trials have been registered for Leber congenital amaurosis 2 (LCA2), retinitis pigmentosa 38, Usher syndrome 1B, Stargardt disease, choroideremia, achromatopsia, Leber hereditary optic neuropathy (LHON) and X-linked retinoschisis. Apart from RPE65 gene therapy for LCA2 and MT-ND4 for LHON which has reached phase III, all other trials are in investigation phase I and II, i.e. testing the efficacy and safety.Because of the relatively easy accessibility of the retina and its ease of visualization which allows monitoring of efficacy, gene-based therapies for inherited retinal disorders represent a very promising treatment option. With the development of novel therapeutic approaches, the importance of establishing not only clinical but also molecular genetic diagnosis is obvious.Key words: gene therapy, monogenic retinal diseases, optic nerve atrophy, mitochondrial disease.

[Clinical Tests Testing New Therapies for Stargardt Disease]. / Klinické zkousky testující nové terapie pro Stargardtovu chorobu.

PURPOSE: To provide information on currently ongoing clinical trials for Stargardt disease. METHODS: We have searched the clinical trial register (www.clinicaltrials.gov) for the keyword "Stargardt" and list active ongoing studies. RESULTS: There are currently eight registered clinical trials enrolling patients with Stargardt disease; all in phase I or II aiming at four mechanisms of action: inhibition of the production of vitamin A toxic dimers, gene therapy restoring wild type transcription of the ABCA4 gene, neuroprotection preventing retinal cells from oxidative damage, and replacement of the damaged retinal pigment epithelium using stem cell therapy. The basic prerequisite for enrolment in the vast majority of clinical trials is confirmation of the clinical diagnosis by mutational analysis. CONCLUSION: The wide variety of therapies that are registered as clinical trials for Stargardt disease significantly raises the possibility that effective treatments will be available in the near future for this currently incurable condition and that molecular genetic testing should be increasingly considered. KEY WORDS: Stargardt disease, clinical trial, ABCA4, mutation.

[Preimplantation genetic diagnosis and monogenic inherited eye diseases]. / Preimplantacní genetická diagnostika a dedicná onemocnení oka.

OBJECTIVE: Preimplantation genetic diagnosis (PGD) is an established application of genetic testing in the context of in vitro fertilization. PGD is an alternative method to prenatal diagnosis which aims to prevent the transmission of an inherited disorder to the progeny by implanting only embryos that do not carry genetic predisposition for a particular disease. The aim of this study is to provide an overview of eye disorders for which PGD has been carried out. METHODS: The European literature search focused on best practices, ethical issues, risks and results of PGD for inherited eye disorders. RESULTS: PGD is performed for a number of ocular disorders; a prerequisite for its application is however, the knowledge of a disease-causing mutation(s). The main advantage of this method is that the couple is not exposed to a decision of whether or not to undergo an abortion. Qualified counselling must be provided prior to the PGD in order to completely understand the risk of disability in any child conceived, consequences of disease manifestation, and advantages as well as limitations of this method. In the group of non-syndromic eye diseases and diseases in which ocular findings dominate, PGD has been performed in European countries for aniridia, choroideremia, congenital fibrosis of extraocular muscles, Leber congenital amaurosis, ocular albinism, retinitis pigmentosa, X-linked retinoschisis, Stargardt disease, blepharophimosis-ptosis-inverse epicanthus syndrome and retinoblastoma. Sexing for X-linked or mitochondrial diseases has been carried out for blue cone monochromatism, choroideremia, familial exudative vitreoretinopathy, Leber hereditary optic neuropathy, macular dystrophy (not further specified), Norrie disease, X-linked congenital stationary night blindness, X-linked retinoschisis and nystagmus (not further specified). CONCLUSION: In recent years, there has been an increase in potential to use PGD. The spectrum of diseases for this method has widened to include severe inherited eye diseases.Key words: preimplantation genetic diagnosis; monogenic eye diseases; in vitro fertilization.

[Blepharophimosis-ptosis-epicanthus inversus syndrome]. / Syndrom blefarofimóza-ptóza-inverzní epikantus.

PURPOSE: To report the ocular phenotype of blepharophimosis-ptosis-epicanthus inversus syndrome (BPES). METHODS: Ophthalmological examination of a 36 year-old proband and detailed family history evaluation, including assessment of available facial photographs of affected relatives, was performed. RESULTS: There were four affected males and one female in three generations. The proband underwent two surgical eyelid procedures in childhood. Upon our examination, he had symmetrical ptosis with shorter eye lids, and incomplete medial canthal closure. The skin in the inner canthi was scarred, and the medial lower lids slightly everted, leading to malapposition of lacrimal punctae. There was no epicanthus inversus, however it was impossible to determine the status prior to the eyelid surgeries. The best corrected visual acuity was 0.66 and 0.33, in the right and left eye, respectively. The rest of the ocular examination was normal. There was no strabismus. Based on inspection of photographs taken prior to eyelid surgeries, the typical signs of BPES were also present in a son and a nephew of the proband. Photographs of the affected brother were not available, but family history indicated that he had BPES and underwent in his childhood two eye lid surgeries. Atypical ocular phenotype of the probands mother has been published previously. CONCLUSIONS: Ophthalmologists need to be aware about the phenotype of BPES, with the potential for visual impairment, and the need for personalized management in the affected families.Key words: blepharophimosis-ptosis-epicanthus inversus, phenotype, FOXL2.

Is copper imbalance an environmental factor influencing keratoconus development?

Keratoconus is a bilateral disease characterized by progressive corneal thinning leading to irregular astigmatism that results in significant visual impairment. Despite extensive research, the exact etiopathogenesis of keratoconus remains unknown. Many copper-dependent enzymes such as superoxide dismutases, cytochrome c oxidase and lysyl oxidase have been shown to be altered in keratoconic corneas, and a decrease of copper levels in the diseased tissue has been reported as well. We propose a hypothesis linking all the putative pathways of keratoconus development and suggest that copper imbalance in corneal tissue may be an independent risk factor for the disease. The assessment of copper levels and its distribution in keratoconic corneas warrants further investigation.

Macular corneal dystrophy and associated corneal thinning.

PURPOSE: To identify the molecular genetic cause of macular corneal dystrophy (MCD) in four probands, and characterize phenotypic similarities between MCD and keratoconus. METHODS: We performed ophthalmological examination, Scheimpflug imaging (Pentacam, Oculus Inc.), histopathological examination of excised corneal buttons, and direct sequencing of the CHST6 coding region. RESULTS: Pentacam measurements were taken in six eyes of three probands. All showed diffuse corneal thinning with paracentral steepening of the anterior corneal surface that was graded as keratoconus by the integrated software, but without associated ectasia of the posterior corneal surface or regional thinning. Homozygous or compound heterozygous CHST6 mutations were identified in all cases, including two novel mutations, c.13C>T; p.(Arg5Cys) and c.289C>T; p.(Arg97Cys). DISCUSSION: Localized elevation of the anterior corneal curvature can occur in MCD in the absence of other features of keratoconus. The identification of a further two Czech probands with the compound allele c.[484C>G; 599T>G] supports the enrichment of this allele in the study population.

[The molecular genetic and clinical findings in two probands with Stargardt disease]. / Molekulárne genetická prícina a klinický nález u dvou probandu se Stargardtovou chorobou.

PURPOSE: The aim of our study was to describe the phenotype and to perform molecular genetic investigation in two probands of Czech origin diagnosed with Stargardt disease (STGD). METHODS: Both males underwent ocular examination including assessment by high-resolution spectral domain optical coherence tomography (SD-OCT). DNA was isolated from venous blood. Mutation detection was performed using the ABCA4 genotyping microarray (Asper Ophthalmics, Estonia). RESULTS: The best corrected visual acuity in proband 1 (aged 39 years) was 0.1 bilaterally, and 0.05 in proband 2 (aged 26 years). Fundus examination showed typical multiple yellow-white lesions and macular atrophy. Alterations of retinal pigment epithelium, retinal thinning and disruption of the photoreceptor inner segment ellipsoid band were detected with an SD-OCT. Two known disease-causing mutations in ABCA4 were identified in proband 1; c.4234C>T, p.(Gln1412*) in exon 28; and c.5882G>A, p.(Gly1961Glu) in exon 42. Only one pathogenic change was detected in proband 2; c.1988G>A, p.(Trp663*) in exon 14. A second change, anticipated because of the recessive status of the disease, was not identified. CONCLUSION: The frequency and full spectrum of ABCA4 mutations in Czech patients with inherited retinal disorders is yet to be established. The inability to detect a second pathogenic change in ABCA4 coding sequences in proband 2 warrants further investigation.

[Clinical findings in members of a Czech family with retinitis pigmentosa caused by the c.2426_2427delAG mutation in RPGR]. / Klinické nálezy u clenu ceské rodiny s retinitis pigmentosa podmínenou mutací v ORF15 genu RPGR.

PURPOSE: To describe the phenotype of members of the first Czech retinitis pigmentosa family with an identified molecular genetic cause (c.2426_2427delAG in RPGR), followed for more than 13 years. METHODS: Medical records were reviewed and a detailed ophthalmic examination including spectral-domain optical coherence tomography and full-field and multifocal electroretinography (ERG) was performed in two affected males, three female carriers and one unaffected female. RESULTS: A 22-year-old male who denied suffering from nyctalopia had a best corrected visual acuity (BCVA) of 0.63 in both eyes. Moderate myopia and myopic astigmatism were present bilaterally. Color vision and contrast sensitivity were normal. There was an eccentric constriction of the visual fields that spared the central 20 degrees in both eyes. Fundus examination revealed bilateral pigmentary changes in the mid-periphery. Full-field ERG documented a 10% rod and 20% cone response. The phenotype of his cousin, also aged 22 years, was more severe. He complained of nyctalopia since 12 years of age. His BCVA was 0.3 in the right eye and 0.5 in the left eye. Myopia and astigmatism were present bilaterally. Contrast sensitivity and color vision were severely impaired. Full field ERG was extinct, but some activity on multifocal ERG was still detectable. The constriction of the visual fields reached 5 degrees in both eyes. Fundus examination showed the typical retinitis pigmentosa appearance. All carriers denied that they suffered from nyctalopia, but two of them had decreased BCVA in at least one eye. None exhibited typical bone spicules or a tapetal-like reflex. Significant refractive errors were present in all eyes of the carriers. CONCLUSION: The finding of moderate or high myopia and astigmatism in males with retinitis pigmentosa as well as refractive errors in female relatives indicates possible X-linked inheritance, which may be especially important in pedigrees where the transmission pattern can not be clearly established. Our study highlights the inter-individual variability in phenotype observed in similar aged patients with identical ORF15 RPGR mutations.

[Retinitis pigmentosa mimicking uveitis. A case report]. / Benigní maskující syndrom u pacientky s retinitis pigmentosa.

PURPOSE: To describe a case report of a 23-year-old patient with retinitis pigmentosa (RP) misdiagnosed as uveitis. METHODS: A comprehensive eye examination including automated visual field assessment, contrast sensitivity, colour vision discrimination, ultrasound examination (US), spectral domain optical coherence tomography (SD-OCT) and full-field electroretinography (ERG) was performed in a patient diagnosed elsewhere as having intermediate uveitis because of the observation of a cellular reaction in the anterior chamber, bilateral cystoid macular oedema and suspected left optic disc swelling. RESULTS: The patient reported nyctalopia. The best corrected visual acuity in both eyes was 6/12. Concentric visual field constriction was detected bilaterally (less than 25 degrees in the right eye and 15 degrees in the left eye). Fundus examination revealed a few pigment clumps and cystoid macular edema in both eyes confirmed by SD-OCT. Contrast sensitivity was decreased to 1,20 in the right and 0,9 in the left. No colour vision disturbance was present. The B scan ultrasound showed left optic disc drusen. Rod ERG responses were bilaterally not detectable and cone ERGs were abnormally reduced. Based on the examination results, a diagnosis of nonsyndromic RP was made. CONCLUSION: Clinicians should be aware of various manifestations of RP, including mild inflammation, to avoid possible confusin with uveitis.

[Minimal ocular findings in a patient with Best disease caused by the c.653G>A mutation in BEST1]. / Minimální nález u pacienta s Bestovou chorobou podmínenou mutací c.653G>A v genu BEST1.

PURPOSE: To describe the phenotype in an asymptomatic 64-year-old patient with family history of Best disease and to identify the disease causing variant in the BEST1 gene. METHODS: Detailed ocular examination of the proband including spectral-domain optical coherence tomography (SD-OCT), fluorescein angiography and electrooculography was performed. Direct sequencing approach was used to screen the whole coding sequence of 11 exons of BEST1. RESULTS: An early vitelliform stage of Best disease presenting as a small yellowish spot in the macula was observed in the right eye. The fundus appearance in the left eye was normal. SD-OCT of the right macula revealed hypodense space between the retinal pigment epithelium and the neuroretinal layer. Arden ratio was bilaterally mildly reduced; 1.36 in the right and 1.3 in the left eye. Molecular genetic analysis identified a heterozygous change c.653G>A (p.Arg218His) as the disease-causing variant. CONCLUSION: Here we report for the first time a phenotype-genotype correlation in a Czech patient with Best disease. SD-OCT is a fast method that may show the presence of small pathological changes. The screening of BEST1 gene enables identification of disease-causing variants in asymptomatic individuals with normal fundus appearance and thus improves counseling to the affected families.

[Immunohistochemical characterization of collagen IV in control corneas and in corneas obtained from patients suffering from posterior polymorphous corneal dystrophy]. / Imunohistochemická charakterizácia kolagénu IV v zdravých rohovkách a rohovkách pacientov so zadnou polymorfnou dystrofiou.

The expression of all six chains of collagen IV was studied using the indirect fluorescent immunohistochemistry in seven control corneas and seven corneas obtained from patients suffering from the posterior polymorphous corneal dystrophy. Heterogeneous staining, especially in the epithelial basement membrane and Descemet's membrane, was observed in the control corneas. An increase of the staining intensity for the alpha1 and alpha2 chains was observed, especially in the Descemet's membrane and the corneal stroma in samples obtained from the patients compared to the control tissues.

Sequencing of the CHST6 gene in Czech macular corneal dystrophy patients supports the evidence of a founder mutation.

AIMS: To characterise the role of the carbohydrate sulfotransferase gene (CHST6) in macular corneal dystrophy (MCD) in Czech patients. METHODS: The coding region of the CHST6 gene was directly sequenced in 10 affected and five unaffected members from eight apparently unrelated MCD families. The type of MCD was determined by enzyme-linked immunosorbent assay of antigenic keratan sulfate (KS) in serum and by immunohistochemical staining of corneas with monoclonal anti-KS antibody. RESULTS: The following changes in the coding sequence of the CHST6 gene were observed; homozygous mutation of c.1A>T (p.M1?); homozygous mutation c.599T>G (p.L200R); compound heterozygosity for c.599T>G and c.614G>A (p.R205Q); compound heterozygosity for c.494G>A (p.C165Y) and c.599T>G; heterozygous c.599T>G mutation and no other change in the coding sequence. One proband exhibited no changes. The pathogenic mutation c.599T>G (p.L200R) was in allelic association with the c.484C>G (p.R162G) polymorphism. Nine patients from seven families were of MCD type I including the subtype IA. CONCLUSION: Four different CHST6 missense mutations, of which p.C165Y is novel, were identified. Allelic association of the c.[484C>G; 599T>G] in six probands out of eight, as well as occurrence of this particular allele in a heterozygous state in one healthy control individual, supports a common founder effect for MCD in the Czech Republic.

[Treatment of severe caustic injuries of the anterior segment of the eye with limbal stem cell transplantation, penetrating keratoplasty and amnionic membrane transplantation]. / Liecba t'azkých poleptaní predného segmentu oka transplantáciou kmenových limbálnych buniek, perforujúcou keratoplastikou a transplantáciou amniovej blany.

The concept of limbal stem cells (LSC) opened new possibilities for the treatment of severe caustic damage of the anterior segment. These possibilities include transplantation of LSC, perforating keratoplasty, possibly transplantation of the amniotic membrane. In three patients with severe caustic damage of the anterior segment of the eye the authors implemented transplantation of LSC, perforating keratoplasty and in one patient also transplantation of the amniotic membrane. Where only one eye was damaged LSC for transplantation were obtained from the sound eye (autotransplantation, in case of damage of both eyes LSC were obtained in one case from a close relative in the second case from a cadaverous eye from a corneal bank (Allotransplantation). In the patient with autotransplantation of LSC, perforating keratoplasty and transplantation of the amniotic membrane the result was very good. The corneal disc remained clear 1.5 years after operation, the conjunctival sac was free from synbleropharons and vision improved from movement of the hand to 0.5. In the two patients with allotransplantation of LCS and perforating keratoplasty, LCS did not become incorporated despite immunosuppressive treatment and the corneal disc became turbid. Restored activity of LCS in severe caustic damage of the anterior segment opened new therapeutic opportunities.