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Updates on the molecular genetics of primary congenital glaucoma (Review).

ABSTRACT: Primary congenital glaucoma (PCG) is one of the primary causes of blindness in children and is characterized by congenital trabecular meshwork and anterior chamber angle dysplasia. While being a rare condition, PCG severely impairs the quality of life of affected patients. However, the pathogenesis of PCG remains to be fully elucidated. It has previously been indicated that genetic factors serve a critical role in the pathogenesis of PCG, although patients with PCG exhibit significant genetic heterogeneity. Mutations in the cytochrome P450 family 1 subfamily B member 1 gene have been implicated in PCG and further genes that have been reported to be involved in PCG are myocilin, forkhead box C1, collagen type I ?1 chain and latent transforming growth factor ? binding protein 2. The present review aims to provide an up to date understanding of the genes associated with PCG and the use of molecular technologies in the identification of such genes and mutations. This may pave the way for the development of preventative methods, early diagnosis and improved therapeutic strategies in PCG.

SUBMITTER: Ling C

PROVIDER: S-EPMC7388405 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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Updates on the molecular genetics of primary congenital glaucoma (Review).

Ling Chen C Zhang Dingding D Zhang Jing J Sun Huanxin H Du Qiu Q Li Xuefei X

Experimental and therapeutic medicine 20200518 2

Primary congenital glaucoma (PCG) is one of the primary causes of blindness in children and is characterized by congenital trabecular meshwork and anterior chamber angle dysplasia. While being a rare condition, PCG severely impairs the quality of life of affected patients. However, the pathogenesis of PCG remains to be fully elucidated. It has previously been indicated that genetic factors serve a critical role in the pathogenesis of PCG, although patients with PCG exhibit significant genetic he ...[more]

PMID: 32742340

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Project description:BackgroundPrimary congenital glaucoma (PCG) manifests within the first few years of a child's life and is not associated with any other systemic or ocular abnormalities. PCG results in considerable morbidity even in developed countries. Several surgical techniques for treating this condition, and lowering the intraocular pressure (IOP) associated with it, have been described.ObjectivesTo compare the effectiveness and safety of different surgical techniques for PCG.Search methodsWe searched CENTRAL (which contains the Cochrane Eyes and Vision Group Trials Register) (The Cochrane Library 2014, Issue 6), Ovid MEDLINE, Ovid MEDLINE In-Process and Other Non-Indexed Citations, Ovid MEDLINE Daily, Ovid OLDMEDLINE (January 1946 to June 2014), EMBASE (January 1980 to June 2014), (January 1982 to June 2014), PubMed (January 1946 to June 2014), the metaRegister of Controlled Trials (mRCT) (www.controlled-trials.com), ClinicalTrials.gov (www.clinicaltrials.gov), the WHO International Clinical Trials Registry Platform (ICTRP) (www.who.int/ictrp/search/en). We did not use any date or language restrictions in the electronic searches for trials. We last searched the electronic databases on 23 June 2014.Selection criteriaWe included all randomized and quasi-randomized trials in which different types of surgical interventions were compared in children under five years of age with PCG.Data collection and analysisWe used standard methodological procedures specified by The Cochrane Collaboration.Main resultsWe included a total of six trials (four randomized and two quasi-randomized) with 102 eyes in 61 children. Two trials were conducted in the USA and one trial each in Egypt, Israel, Lebanon and Saudi Arabia. All trials included children aged younger than one year when diagnosed with PCG, and followed them for periods ranging from six months to five years.No two trials compared the same pair of surgical interventions, so we did not perform any meta-analysis. One trial compared trabeculotomy versus goniotomy; a second trial compared combined trabeculectomy-trabeculotomy with mitomycin C versus trabeculectomy-trabeculotomy with mitomycin C and deep sclerectomy; a third trial compared combined trabeculotomy-trabeculectomy versus trabeculotomy; a fourth trial compared one goniotomy versus two goniotomies; a fifth trial compared trabeculotomy versus viscocanalostomy; and the sixth trial compared surgical goniotomy versus neodymium-YAG laser goniotomy. For IOP change and surgical success (defined by IOP achieved), none of the trials reported a difference between pairs of surgical techniques. However, due to the limited sample sizes for all trials (average of 10 children per trial), the evidence as to whether a particular surgical technique is effective and which surgical technique is better still remains uncertain. Adverse events, such as choroidal detachment, shallow anterior chamber and hyphema, were reported from four trials. None of the trials reported quality of life or economic data.These trials were neither designed nor reported well overall. Two trials were quasi-randomized trials and judged to have high risk of selection bias; four trials were at unclear or high risk for performance bias and detection bias; and we judged one trial to have high risk of attrition bias due to high proportions of losses to follow-up. Due to poor study design and reporting, the reliability and applicability of evidence remain unclear.Authors' conclusionsNo conclusions could be drawn from the trials included in this review due to paucity of data. More research is needed to determine which of the many surgeries performed for PCG are effective.

Project description:PurposeTo screen mitochondrial DNA (mtDNA) for nucleotide variations in primary congenital glaucoma (PCG).MethodsThe entire coding region of the mitochondrial genome was amplified by polymerase chain reaction from 35 PCG patients and 40 controls. The full mtDNA genome except the D-loop was sequenced. All sequences were analyzed against mitochondrial reference sequence NC_012920.ResultsMtDNA sequencing revealed a total of 132 and 58 nucleotide variations in PCG and controls, respectively. Of 132 nucleotide variations, 42 (31.81%) were non-synonymous and 82 (62.12%) were synonymous changes, and 8 were in RNA genes. The highest number of nucleotide variations were recorded in complex I followed by complex IV, then complex V. Eight patients (22.85%) had potentially pathogenic mtDNA nucleotide changes and twenty (57.14%) had mtDNA sequence changes associated with elevated reactive oxygen species (ROS) production. Mitochondria not only constitute the energy-generating system in the cell, but are also critically involved in calcium signaling and apoptosis. Mitochondrial function can be affected by mutations in mitochondrial and nuclear DNA, chemical insults to components of the electron transport chain, and a lack of substrates such as oxygen. Mitochondrial dysfunction results in an excessive generation of free radicals and reduced mitochondrial respiration. Developing trabecular meshwork (TM) is deficient in antioxidant enzymes, and thus is more susceptible to oxidative stress (OS) induced damage. Previous studies have documented certain mtDNA sequence variations associated with elevated ROS levels and OS. Three such changes (G10398A, A12308G, and G13708A) were present in our patients. Elevated ROS may cause OS. This OS may further damage mtDNA and may cause decreased mitochondrial respiration. This may lead to impaired growth, development and differentiation of TM and consequently trabecular-dysgenesis, which is a characteristic feature of PCG. OS affects both TM and retinal ganglion cells (RGCs) and may be involved in the neuronal death affecting the optic nerve in glaucoma. There are several studies which point to mitochondrial dysfunction in different types of glaucoma and critically participate in RGC death. Recent studies also implicate mitochondrial dysfunction-associated OS as a risk factor for glaucoma patients. It has been reported that elevated hydrostatic pressure causes breakdown of the mitochondrial network by mitochondrial fission and induce cristae depletion and cellular ATP reduction in differentiated RGC-5 cells in vitro as well as in vivo.ConclusionsA total of 44 novel mtDNA variations were identified in this study. Non-synonymous mtDNA variations may adversely affect respiratory chain, impair OXPHOS pathway result in low ATP production, high ROS production and impair growth, development and differentiation of TM lead to trabecular-dysgenesis and consequently RGC's death. Such cases with mtDNA variations and consequent OS may benefit by early diagnosis and prompt management by antioxidant therapy. This may delay OS induced injury to TM and RGCs and hence improve visual prognosis.

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Updates on the molecular genetics of primary congenital glaucoma (Review).

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Updates on the molecular genetics of primary congenital glaucoma (Review).

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