Pseudoretinoblastoma: Distribution Based on Gender, Age, and Laterality

Purpose: To investigate the distribution of pseudoretinoblastoma (PSRB) cases based on gender, age, and lateralityMethods: The clinical records of 607 patients (851 eyes) who were referred for suspicion of retinoblastoma between October 1998 and May 2021 were retrospectively evaluated. Patients were stratified by age as follows: ≤1 year, >1-3 years, >3-5 years, and >5 years.Results: PSRB conditions were detected in 190/607 (31.3%) patients. Of 190 patients, 129 (67.9%) were males and 61 (32.1%) were females (p=0.001). The 3 most common diagnoses were persistent fetal vasculature (PFV; 16.3%), Coats disease (15.3%), and optic nerve head drusen (ONHD; 5.3%). In males, the 3 most common diagnoses were Coats disease (20.2%), PFV (14.0%), and chorioretinal coloboma (6.2%). The 3 most common diagnoses in females included PFV (21.3%), retinal dysplasia, congenital glaucoma, and combined hamartoma (each accounting for 6.6%). PFV was the most common diagnosis in ≤1 year old patient group (26.6%). Coats disease and PFV were the most common diagnoses in >1-3 years old patient group (16.7%, for each diagnosis). Coats disease was the most common diagnosis in >3-5 years old (30.8%) and >5 years old patient groups (13.1%). PSRBs were unilateral in 121/190 (63.7%) patients and bilateral in 69/190 (36.3%). The most common unilateral and bilateral diagnoses were Coats disease (24.0%) and PFV (24.6%) respectively.Conclusion: In our study, 31.3% of patients referred for suspicion of retinoblastoma received the diagnosis of PSRB. PSRB spectrum encompasses different diseases, the distribution of which differ depending on gender, age, and laterality.

Congenital Cataracts and Microphakia with Retinal Dysplasia and Optic Nerve Hypoplasia in a Calf

Case Description. A two-month-old, female, Aberdeen-Angus calf was presented for congenital cataracts and blindness in both eyes (OU). The dam had a reported history of visual defects (not specified) and had produced other affected calves (per owner history). Ophthalmic examination revealed mature bilateral cataracts, attenuation of the iridic granules, persistent pupillary membranes, and dyscoric pupils. Additionally, the calf had a poor body condition, prognathism, dome-shaped head, excessive nasal drainage, limb contracture, and fever. Histopathology of both eyes revealed lenticular degeneration (congenital cataracts), retinal dysplasia, and optic nerve hypoplasia. BVDV IHC detected antigen within only the left eye (OS), consisting of intrahistiocytic and endothelial immunoreactivity within the ciliary body, iris, and choroid. No BVDV immunoreactivity could be detected in the right eye (OD). This case highlights the unique ocular changes present in in utero BVDV infection of cattle with a different immunohistochemical staining profile than previously described.

Identification of Arhgef12 and Prkci as Genetic Modifiers of Retinal Dysplasia in the Crb1rd8 Mouse Model

Mutations in the apicobasal polarity gene CRB1 lead to diverse retinal diseases, such as Leber congenital amaurosis, cone-rod dystrophy, retinitis pigmentosa (with and without Coats-like vasculopathy), foveal retinoschisis, macular dystrophy, and pigmented paravenous chorioretinal atrophy. Limited correlation between disease phenotypes and CRB1 alleles, and evidence that patients sharing the same alleles often present with different disease features, suggest that genetic modifiers contribute to clinical variation. Similarly, the retinal phenotype of mice bearing the Crb1 retinal degeneration 8 (rd8) allele varies with genetic background. Here, we initiated a sensitized chemical mutagenesis screen in B6.Cg-Crb1rd8/Pjn, a strain with a mild clinical presentation, to identify genetic modifiers that cause a more severe disease phenotype. Two models from this screen, Tvrm266 and Tvrm323, exhibited increased retinal dysplasia. Genetic mapping with high-throughput exome and candidate-gene sequencing identified causative mutations in Arhgef12 and Prkci, respectively. Epistasis analysis of both strains indicated that the increased dysplastic phenotype required homozygosity of the Crb1rd8 allele. Retinal dysplastic lesions in Tvrm266 mice were smaller and caused less photoreceptor degeneration than those in Tvrm323 mice, which developed an early, large diffuse lesion phenotype. In both models at one month of age, Müller glia and microglia mislocalization at dysplastic lesions was similar to that in B6.Cg-Crb1rd8/Pjn mice, while photoreceptor cell mislocalization was more extensive. External limiting membrane disruption was comparable in Tvrm266 and B6.Cg- Crb1rd8/Pjn mice but milder in Tvrm323 mice. Immunohistological analysis of mice at postnatal day 0 indicated a normal distribution of mitotic cells in Tvrm266 and Tvrm323 mice, suggesting normal early development. Aberrant electroretinography responses were observed in both models but functional decline was significant only in Tvrm323 mice. These results identify Arhgef12 and Prkci as modifier genes that differentially shape Crb1-associated retinal disease, which may be relevant to understanding clinical variability and underlying disease mechanisms.

Unilateral Familial Exudative Vitreoretinopathy: Clinical Profile and Pathology

We report a case of a newborn with unilateral retinal detachment that could not be repaired. At examination under anesthesia, the retina was markedly abnormal and a presumptive diagnosis of retinal dysplasia was made. Several years later, the eye was enucleated because it was blind and painful. Final pathology was consistent with familial exudative vitreoretinopathy (FEVR). The literature describing unilateral retinal dysplasia is sparse. This case adds to the clinical spectrum of pathologic findings in FEVR.

First person – Gabriel Matos-Rodrigues

ABSTRACTFirst Person is a series of interviews with the first authors of a selection of papers published in Disease Models & Mechanisms, helping early-career researchers promote themselves alongside their papers. Gabriel Matos-Rodrigues is first author on ‘Progenitor death drives retinal dysplasia and neuronal degeneration in a mouse model of ATRIP-Seckel syndrome’, published in DMM. Gabriel conducted the research described in this article while a PhD student in Rodrigo A. P. Martins's lab at Universidade Federal do Rio de Janeiro, Rio de Janeiro, Brazil. He is now a PhD student in the lab of Bernard S. Lopez at Université de Paris, Paris, France, investigating mechanisms of DNA repair and DNA damage response.

Progenitor death drives retinal dysplasia and neuronal degeneration in a mouse model of ATRIP-Seckel syndrome

ABSTRACTSeckel syndrome is a type of microcephalic primordial dwarfism (MPD) that is characterized by growth retardation and neurodevelopmental defects, including reports of retinopathy. Mutations in key mediators of the replication stress response, the mutually dependent partners ATR and ATRIP, are among the known causes of Seckel syndrome. However, it remains unclear how their deficiency disrupts the development and function of the central nervous system (CNS). Here, we investigated the cellular and molecular consequences of ATRIP deficiency in different cell populations of the developing murine neural retina. We discovered that conditional inactivation of Atrip in photoreceptor neurons did not affect their survival or function. In contrast, Atrip deficiency in retinal progenitor cells (RPCs) led to severe lamination defects followed by secondary photoreceptor degeneration and loss of vision. Furthermore, we showed that RPCs lacking functional ATRIP exhibited higher levels of replicative stress and accumulated endogenous DNA damage that was accompanied by stabilization of TRP53. Notably, inactivation of Trp53 prevented apoptosis of Atrip-deficient progenitor cells and was sufficient to rescue retinal dysplasia, neurodegeneration and loss of vision. Together, these results reveal an essential role of ATRIP-mediated replication stress response in CNS development and suggest that the TRP53-mediated apoptosis of progenitor cells might contribute to retinal malformations in Seckel syndrome and other MPD disorders.This article has an associated First Person interview with the first author of the paper.

Coincidental retinal dysplasia in patients presenting with pseudohypopyon: a series of two cases

Clinical diagnosis is always challenging in cases with atypical presentation. Herein, we present two cases which masqueraded as ocular infection/inflammation on presentation, were clinically suspicious for retinoblastoma, and histopathology revealed the diagnosis of retinal dysplasia. Case 1 had left corneal perforation with anterior chamber exudates on presentation. On ultrasound B-scan, ill-defined mass was noted, raising a suspicion of malignancy. MRI showed dilated ventricles with midline shift. Vitreous cytology was inconclusive. Enucleation was performed as malignancy could not be ruled out. Histopathology revealed detached retina with dysplastic rosettes in addition to inflammation and multinucleate giant cell reaction. Case 2 presented with right eye anterior chamber pseudohypopyon. Fundus examination revealed diffuse vitreous haze and a suspicious mass in the retinal periphery raising suspicion for retinoblastoma. Histopathology revealed the diagnosis of retinal dysplasia.