Venous Tortuosity in COL4A2-Associated Gould Syndrome.

Mutations in collagen-encoding genes have been linked to numerous systemic diseases. Specifically, pathologic alterations in COL4A2 have been linked to Gould syndrome, a hereditary angiopathy affecting the brain, kidneys, and eyes. However, the ocular phenotype associated with COL4A2-associated disease has yet to be fully characterized. In this report, we describe a novel variant in COL4A2 identified in a 48-year-old woman and her 15-year-old daughter. Funduscopic examination demonstrated significant venous and arteriolar tortuosity. Genetic testing revealed a novel variant, c.2321G>A:p.(Gly774Glu), in COL4A2. This vascular phenotype is similar to the familial retinal arterial tortuosity seen in COL4A2-associated Gould syndrome with additional venous involvement. [Ophthalmic Surg Lasers Imaging Retina 2023;54:536-539.].

Osteopathia striata with cranial sclerosis causing a compressive optic neuropathy.

BACKGROUND: Osteopathia striata combined with cranial sclerosis (OS-CS) is an inherited skeletal dysplasia that manifests with macrocephaly, orofacial abnormalities, thickened craniofacial bones, and vertically oriented radiodensities of the long bones. CASE REPORT: Here, we present a severe case of OS-CS in a 4-year-old girl causing optic neuropathy as shown by radiographic evidence, ophthalmic findings, and histopathology. Previous genetic testing in this patient revealed a de novo heterozygous mutation in AMER1 (c.1057C>T, p.Arg353Ter). Although the patient had a pre-existing, appropriately functioning, ventriculoperitoneal (VP) shunt, a subsequent MRI of the brain and orbits showed narrowing of the bilateral optic nerve canals secondary to osseous thickening causing bilateral optic nerve atrophy, worse on the left. The patient underwent staged bilateral orbital osteotomies, optic canal decompression, and bilateral frontal craniotomy, and at 11 months postoperatively, her vision remained stable. Conclusions: While up to 50% of the patients with OS-CS may experience hearing loss due to cranial nerve compression, we present a case of severe visual loss secondary to OS-CS-associated optic nerve compression.

Indolent Nonprogressive Multifocal Choroidal Lymphoid Lesions: A Clinical-Histopathological Correlation.

PURPOSE: To present the clinicopathologic correlation of indolent nonprogressive multifocal choroidal lesions, clinically presumed to be lymphoid in nature, using multimodal imaging and histopathological analysis of a donor eye. DESIGN: Case study and clinicopathological correlation. PARTICIPANTS: A 77-year-old man of Caucasian ancestry with indolent, nonprogressive, multifocal, choroidal infiltration of his right eye, presumed to be lymphocytic in nature based on the appearance of the lesions, was followed up for 19 years. METHODS: Multimodal imaging, including fundus photography, B-scan ultrasonography, OCT, fluorescein angiography, and indocyanine green angiography, was performed throughout the 19 years of follow-up before the patient's death. The involved eye was preserved 21 hours postmortem and analyzed using standard histopathological and immunohistochemical techniques. MAIN OUTCOME MEASURES: Correlation of findings on multimodal imaging with histopathological and immunohistochemical findings in the involved eye. RESULTS: Clinical examination over the course of 19 years showed no deterioration in the visual acuity of the involved eye. Multimodal imaging revealed yellow-orange choroidal lesions that showed no appreciable progression during the 19 years of follow-up. These areas stained minimally on fluorescein angiography. Indocyanine green angiography revealed tortuous choroidal vessels and fluorescence blockage. Enhanced-depth imaging OCT revealed hyporeflective, homogenous choroidal thickening. Light microscopy, histopathology, and immunohistochemistry showed that the lesions were composed of small, mature-appearing B cells that spared the choriocapillaris. The findings were most consistent with extranodal marginal-zone lymphoma of the mucosa-associated lymphoid tissue (MALT). CONCLUSIONS: Indolent, nonprogressive, multifocal, choroidal lymphoid lesions in this patient remained confined to the choroid, as determined based on the clinical examination and imaging for almost 2 decades, with no clinical evidence of extension into the retina. Light microscopy, histopathology, and immunohistochemistry postmortem showed that the lesions were composed of small, mature-appearing B cells that spared the choriocapillaris. The findings were consistent with extranodal marginal-zone lymphoma of the MALT. This entity is distinct from more aggressive uveal and choroidal lymphomas and is expected to remain relatively stationary on long-term clinical follow-up, with a good visual prognosis.

ARE THERE TWO FORMS OF MULTIPLE EVANESCENT WHITE DOT SYNDROME?

PURPOSE: To analyze the nature of multiple evanescent white dot syndrome (MEWDS) and differentiate an idiopathic or primary form of MEWDS from a secondary form that is seen in association with other clinical conditions affecting the posterior segment of the eye. METHODS: Clinical and multimodal imaging findings including color fundus photography, fundus autofluorescence, fluorescein angiography, indocyanine green angiography, spectral-domain optical coherence tomography, and optical coherence tomography angiography of patients with secondary MEWDS are presented. RESULTS: Twenty consecutive patients with secondary MEWDS were evaluated. Fifteen patients were female. Most were young adults aged between 20 to 40 years with myopia (less than -6 diopters). Pathologic conditions associated with the secondary MEWDS reaction were high myopia (greater than -6 diopters) in two eyes, previous vitreoretinal surgery for rhegmatogenous retinal detachment in 2 eyes, and manifestations of multifocal choroiditis in 18 eyes. In all eyes, the MEWDS lesions followed a course of progression and resolution independent from the underlying condition. CONCLUSION: Secondary MEWDS seems to be an epiphenomenon ("EpiMEWDS") that may be seen in association with clinical manifestations disruptive to the choriocapillaris-Bruch membrane-retinal pigment epithelium complex.

Unique histopathologic features of the eyelid dermatofibroma.

Purpose: Dermatofibromas are common cutaneous lesions, but rarely occur in the eyelid skin. The reason for the low incidence in the palpebral skin has not been elucidated. In this study, we analyze the histopathologic features of an illustrative case of dermatofibroma and review previously published cases to determine whether eyelid dermatofibroma develops differently from the prototypical dermatofibroma. Methods: Histopathologic analysis of a new illustrative case of eyelid dermatofibroma and retrospective review of published cases. Results: The distinguishing features of the illustrative lesion included a rounder gross appearance, nonacanthotic epithelium, basophilic staining, cellular character, and a paucity of "collagen trapping." These features deviated from the typical features associated with classic dermatofibroma. Review of the 11 previously published cases of eyelid dermatofibroma revealed that they were more similar in appearance to the illustrative lesion than to classic dermatofibroma. Discussion: The rarity and histological deviations of the eyelid dermatofibroma suggest that the dermal substrate from which the lesion develops differs from that of the classic dermatofibroma. This difference may be explained microanatomically based on the fact that the dermis of the eyelid is predominantly papillary, whereas the dermis of extrapalpebral skin where dermatofibromas are more common is predominantly reticular. Conclusions: Although related, eyelid dermatofibromas appear to be histologically distinct from classic dermatofibromas, owing to the unique dermal composition of the site of origin.

Gene Therapy Restores Mfrp and Corrects Axial Eye Length.

Hyperopia (farsightedness) is a common and significant cause of visual impairment, and extreme hyperopia (nanophthalmos) is a consequence of loss-of-function MFRP mutations. MFRP deficiency causes abnormal eye growth along the visual axis and significant visual comorbidities, such as angle closure glaucoma, cystic macular edema, and exudative retinal detachment. The Mfrp rd6 /Mfrp rd6 mouse is used as a pre-clinical animal model of retinal degeneration, and we found it was also hyperopic. To test the effect of restoring Mfrp expression, we delivered a wild-type Mfrp to the retinal pigmented epithelium (RPE) of Mfrp rd6 /Mfrp rd6 mice via adeno-associated viral (AAV) gene therapy. Phenotypic rescue was evaluated using non-invasive, human clinical testing, including fundus auto-fluorescence, optical coherence tomography, electroretinography, and ultrasound. These analyses showed gene therapy restored retinal function and normalized axial length. Proteomic analysis of RPE tissue revealed rescue of specific proteins associated with eye growth and normal retinal and RPE function. The favorable response to gene therapy in Mfrp rd6 /Mfrp rd6 mice suggests hyperopia and associated refractive errors may be amenable to AAV gene therapy.

Retinal reattachment and ERG recovery after ophthalmic artery chemosurgery for advanced retinoblastoma in eyes with minimal baseline retinal function.

AIM: To report retinal function outcomes after ophthalmic artery chemosurgery (OAC) for advanced retinoblastoma (RB) in eyes with minimal pretreatment retinal function. METHODS: For 72 advanced RB eyes with baseline electroretinograms (ERGs) indistinguishable from noise ('extinguished') or flicker ERG amplitudes <25 µV ('poor'), ERGs were obtained before OAC and at 3 months, 1 year and 2 years after OAC. Presence of baseline retinal detachments (RDs) and their subsequent resolution or persistence was also noted. RESULTS: At 3 months, 1 year and 2 years post-OAC, 'extinguished' eyes showed 9/15, 4/11 and 2/6 detectable ERGs, respectively, and 'poor' eyes showed 19/55, 14/30 and 8/18 ERGs exceeding 25 µV, respectively. Correlations between baseline and post-OAC ERGs were poor; however, good correlation (R2) existed between ERGs post-OAC at 3 months and 1 year (0.749), at 3 months and 2 years (0.773) and at 1 year and 2 years (0.771). Overall, 49/70 eyes presented with RD; 29 RDs resolved 3 months post-OAC, with an average ERG change of +20.6 µV. Eyes with persistent RD had an average ERG change of -2.2 µV. No eyes underwent ≥25 µV change without RD resolution. CONCLUSIONS: Minimal baseline ERGs do not preclude significant recovery of retinal function after OAC. Good correlation exists between ERG outcomes at 3 months and those at subsequent follow-ups, suggesting that ERG amplitudes at 3-month post-OAC can prognosticate longer term retinal function, and that improvement is durable. For eyes presenting with RD, RD resolution is necessary but not sufficient for significant (≥25 µV) increases in ERG amplitudes.

The AAA+ ClpX machine unfolds a keystone subunit to remodel the Mu transpososome.

A hyperstable complex of the tetrameric MuA transposase with recombined DNA must be remodeled to allow subsequent DNA replication. ClpX, a AAA+ enzyme, fulfills this function by unfolding one transpososome subunit. Which MuA subunit is extracted, and how complex destabilization relates to establishment of the correct directionality (left to right) of Mu replication, is not known. Here, using altered-specificity MuA proteins/DNA sites, we demonstrate that transpososome destabilization requires preferential ClpX unfolding of either the catalytic-left or catalytic-right subunits, which make extensive intersubunit contacts in the tetramer. In contrast, ClpX recognizes the other two subunits in the tetramer much less efficiently, and their extraction does not substantially destabilize the complex. Thus, ClpX targets the most stable structural components of the complex. Left-end biased Mu replication is not, however, determined by ClpX's intrinsic subunit preference. The specific targeting of a stabilizing "keystone subunit" within a complex for unfolding is an attractive general mechanism for remodeling by AAA+ enzymes.

Unique contacts direct high-priority recognition of the tetrameric Mu transposase-DNA complex by the AAA+ unfoldase ClpX.

Clp/Hsp100 ATPases remodel and disassemble multiprotein complexes, yet little is known about how they preferentially recognize these complexes rather than their constituent subunits. We explore how substrate multimerization modulates recognition by the ClpX unfoldase using a natural substrate, MuA transposase. MuA is initially monomeric but forms a stable tetramer when bound to transposon DNA. Destabilizing this tetramer by ClpX promotes an essential transition in the phage Mu recombination pathway. We show that ClpX interacts more tightly with tetrameric than with monomeric MuA. Residues exposed only in the MuA tetramer are important for enhanced recognition--which requires the N domain of ClpX--as well as for a high maximal disassembly rate. We conclude that an extended set of potential enzyme contacts are exposed upon assembly of the tetramer and function as internal guides to recruit ClpX, thereby ensuring that the tetrameric complex is a high-priority substrate.