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The American Journal of Case Reports Sep 2020BACKGROUND Retinal vasoproliferative tumor (VPT) is a type of ocular vascular tumor that commonly occurs idiopathically and can be associated with secondary ocular...
BACKGROUND Retinal vasoproliferative tumor (VPT) is a type of ocular vascular tumor that commonly occurs idiopathically and can be associated with secondary ocular diseases. Ocular albinism is an X-linked inherited disease and distinguished from oculocutaneous albinism by less hair and skin involvement. CASE REPORT A 42-year-old man with ocular albinism and moderate myopia presented with a history of insidious decrease in vision in both eyes over a period of months. On examination, the horizontal pendular nystagmus was present and diffuse iris transillumination defects were observed bilaterally. A fundus examination revealed a depigmented fundus with visible choroidal vessels, foveal hypoplasia, and a unilateral, elevated, vascular lesion in the superotemporal aspect of the retinal periphery. Optical coherence tomography of the lesion confirmed the retinal location and fluorescein fundus angiography indicated its vascular nature. B-scan ultrasonography was performed to measure the dimensions of the lesion. CONCLUSIONS Rare retinal VPT has been reported with systemic and ocular associations, but it has never been reported in the literature in association with ocular albinism. Multiple treatment modalities have been described for the tumor, but observation can be considered in the absence of secondary consequences of the VPT. Retinal VPT should be included in the differential diagnosis of any retinal vascular abnormalities in patients with ocular albinism.
Topics: Adult; Albinism, Ocular; Albinism, Oculocutaneous; Fluorescein Angiography; Fundus Oculi; Humans; Male; Tomography, Optical Coherence
PubMed: 32895362
DOI: 10.12659/AJCR.925926 -
Integrative and Comparative Biology Oct 2021Melanins, the main pigments of the skin and hair in mammals, are synthesized within membrane-bound organelles of melanocytes called melanosomes. Melanosome structure and... (Review)
Review
Melanins, the main pigments of the skin and hair in mammals, are synthesized within membrane-bound organelles of melanocytes called melanosomes. Melanosome structure and function are determined by a cohort of resident transmembrane proteins, many of which are expressed only in pigment cells and localize specifically to melanosomes. Defects in the genes that encode melanosome-specific proteins or components of the machinery required for their transport in and out of melanosomes underlie various forms of ocular or oculocutaneous albinism, characterized by hypopigmentation of the hair, skin, and eyes and by visual impairment. We review major components of melanosomes, including the enzymes that catalyze steps in melanin synthesis from tyrosine precursors, solute transporters that allow these enzymes to function, and structural proteins that underlie melanosome shape and melanin deposition. We then review the molecular mechanisms by which these components are biosynthetically delivered to newly forming melanosomes-many of which are shared by other cell types that generate cell type-specific lysosome-related organelles. We also highlight unanswered questions that need to be addressed by future investigation.
Topics: Animals; Mammals; Melanins; Melanocytes; Melanosomes; Pigmentation
PubMed: 34021746
DOI: 10.1093/icb/icab078 -
Ophthalmology. Retina May 2024
PubMed: 38739070
DOI: 10.1016/j.oret.2024.04.011 -
Graefe's Archive For Clinical and... Nov 2023To report the association of tilted disc (TD) with fovea plana.
PURPOSE
To report the association of tilted disc (TD) with fovea plana.
METHODS
Monocentric retrospective study of consecutive eyes diagnosed with fovea plana, assessed by spectral-domain optical coherence tomography. Analysis of the medical charts and imaging findings of patients to collect demographics, the visual acuity, and the clinical context. The presence of associated conditions was checked by two independent readers in order to classify fovea plana as isolated or part of other conditions.
RESULTS
Twenty-one patients, 9 men and 12 women, aged 12 to 91 years, were included. Fovea plana was isolated and asymptomatic in 10 (47.6%) patients. In 6 (28.5%) patients, fovea plana was associated with ocular albinism and/or nystagmus. In 6 (28.5%) patients, fovea plana was associated with an obliquity of the optic disc typical of TD, isolated (5 cases), or associated with nystagmus (1 case).
CONCLUSION
An association between TD and fovea plana had been reported only once in the literature and had been considered likely coincidental. However, this association could be more common than initially reported and suggests a common pathological process in eye development during embryogenesis.
PubMed: 37351645
DOI: 10.1007/s00417-023-06161-7 -
International Ophthalmology Jun 2022Childhood blindness is important cause contributing to the burden of blindness. It is necessary to identify the most frequently observed diseases in different...
PURPOSE
Childhood blindness is important cause contributing to the burden of blindness. It is necessary to identify the most frequently observed diseases in different populations. We aimed to demonstrate clinical features of low vision children and to evaluate the factors affecting visual function by a new visual function scoring system.
METHODS
Two hundred forty nine children between the age of 6 months and 3 years were included. Visual function was scored from 0 to 15 according to; response to threat, light, object, presence of fixation, duration of fixation, following of light and object in horizontal, vertical, oblique, and circular gazes, optokinetic nystagmus. Patients were classified according to neurological diagnosis and cranial magnetic resonance imaging findings. Correlation between visual function score and ocular and neurologic findings were evaluated.
RESULTS
While 136 patients (54.6%) had cerebral visual impairment (CVI), 89 (35.7%) had ocular pathology, 24 patients (9.6%) had combined pathology. The most common ocular and cerebral pathologies were oculocutaneous albinism (23.9%) and hypoxic ischemic encephalopathy (HIE) (27.5%), respectively. Patients with CVI had lower visual function than ocular pathologies. Neurological structural disorders and HIE had worse visual function. Widespread involvement of brain had lower visual function score. Seizure negatively affected visual function.
CONCLUSIONS
Cerebral causes were found in approximately half of infants and children with low vision who were referred to our center for visual habilitation. The visual function scoring system we developed in this study will provide an opportunity to be objective in the follow-up of babies and in evaluating the effectiveness of visual habilitation programs.
Topics: Blindness; Brain Diseases; Child; Child, Preschool; Humans; Infant; Nervous System Diseases; Vision Disorders; Vision, Low; Visual Acuity
PubMed: 35088360
DOI: 10.1007/s10792-021-02187-0 -
Frontiers in Molecular Biosciences 2022GPCRs transform extracellular stimuli into a physiological response by activating an intracellular signaling cascade initiated via binding to G proteins. Orphan G... (Review)
Review
GPCRs transform extracellular stimuli into a physiological response by activating an intracellular signaling cascade initiated via binding to G proteins. Orphan G protein-coupled receptors (GPCRs) hold the potential to pave the way for development of new, innovative therapeutic strategies. In this review we will introduce G protein-coupled receptor 143 (GPR143), an enigmatic receptor in terms of classification within the GPCR superfamily and localization. GPR143 has not been assigned to any of the GPCR families due to the lack of common structural motifs. Hence we will describe the most important motifs of classes A and B and compare them to the protein sequence of GPR143. While a precise function for the receptor has yet to be determined, the protein is expressed abundantly in pigment producing cells. Many GPR143 mutations cause X-linked Ocular Albinism Type 1 (OA1, Nettleship-Falls OA), which results in hypopigmentation of the eyes and loss of visual acuity due to disrupted visual system development and function. In pigment cells of the skin, loss of functional GPR143 results in abnormally large melanosomes (organelles in which pigment is produced). Studies have shown that the receptor is localized internally, including at the melanosomal membrane, where it may function to regulate melanosome size and/or facilitate protein trafficking to the melanosome through the endolysosomal system. Numerous additional roles have been proposed for GPR143 in determining cancer predisposition, regulation of blood pressure, development of macular degeneration and signaling in the brain, which we will briefly describe as well as potential ligands that have been identified. Furthermore, GPR143 is a promiscuous receptor that has been shown to interact with multiple other melanosomal proteins and GPCRs, which strongly suggests that this orphan receptor is likely involved in many different physiological actions.
PubMed: 35495622
DOI: 10.3389/fmolb.2022.873777 -
Klinische Monatsblatter Fur... Mar 2016From the ophthalmological view, albinism is a disorder of reduced pigmentation of the retinal and irdial pigment epithelium and the iris and choroid stroma. The reduced... (Review)
Review
From the ophthalmological view, albinism is a disorder of reduced pigmentation of the retinal and irdial pigment epithelium and the iris and choroid stroma. The reduced pigmentation is accompanied by morphological changes in the retina and the optic nerve. The functional relationship of these morphological changes is not yet well understood. This review summarises the genetic causes of reduced pigment synthesis and impaired pigment distribution, and discusses the variability of expression of albinism symptoms, in the light of other disorders affecting retinal development.
Topics: Albinism, Ocular; Eye Proteins; Genetic Predisposition to Disease; Humans; Macula Lutea; Mutation; Nystagmus, Congenital; Retinal Diseases
PubMed: 27011028
DOI: 10.1055/s-0042-101556 -
Klinische Monatsblatter Fur... Apr 2023Nystagmus describes an involuntary, periodic movement of one or both eyes. About 1/600 children and adolescents have nystagmus, most of them idiopathic infantile...
Nystagmus describes an involuntary, periodic movement of one or both eyes. About 1/600 children and adolescents have nystagmus, most of them idiopathic infantile nystagmus (IIN), also called "congenital nystagmus", which can be caused by mutations in the gene. Other frequent forms of nystagmus are latent nystagmus, which is usually associated with infantile strabismus, and nystagmus associated with albinism. Sometimes difficult to distinguish in young infants is a sensory nystagmus, where a defect in the visual system reduces vision and causes nystagmus. Causes include retinal dystrophies, congenital stationary night blindness and structural ocular defects including optic nerve hypoplasia or dense bilateral congenital cataracts. Unilateral nystagmus can be the sign of an anterior visual pathway lesion. Seesaw nystagmus may be associated with suprasellar and mesodiencephalic lesions and - rarely - with retinal dystrophies.The ophthalmology plays a key role in identifying the form of nystagmus. Children with new onset nystagmus, with spasmus nutans, with vertical or unilateral nystagmus and those with seesaw nystagmus require neurologic evaluation including imaging of the brain.The treatment of nystagmus depends on the underlying cause. Even minor refractive errors should be corrected, contact lenses offer advantages over glasses.Gabapentin and memantine, possibly also carbonic anhydrase inhibitors, are effective in treating IIN, nystagmus in albinism and sensory nystagmus. Nevertheless, pharmacologic treatment of nystagmus is rarely used in children; the reasons are the limited effects on vision, the need for lifelong therapy, and potential side effects. Eye muscle surgery (Anderson procedure, Kestenbaum procedure) can correct a nystagmus-related anomalous head posture. The concept of "artifical divergence" of Cüppers may help to decrease nystagmus intensity in patients whose nystagmus dampens with convergence. The four-muscle-tenotomy, which involves disinsertion and reinsertion of the horizontal muscles at the original insertion of both eyes, has a proven but limited positive effect on visual acuity.
Topics: Infant; Adolescent; Child; Humans; Nystagmus, Pathologic; Nystagmus, Congenital; Eye Movements; Oculomotor Muscles; Albinism; Cytoskeletal Proteins; Membrane Proteins
PubMed: 36827996
DOI: 10.1055/a-2022-1111 -
Neuropediatrics Feb 2022The aim of this study was to detail the neurodevelopmental profile of subjects affected by ocular albinism (OA) and to collect data on GPR143 gene analysis.
AIM
The aim of this study was to detail the neurodevelopmental profile of subjects affected by ocular albinism (OA) and to collect data on GPR143 gene analysis.
DESIGN
The design of the study involves a retrospective longitudinal observational case series.
METHODS
We collected data on the neurodevelopmental profile of 13 children affected by OA from clinical annual assessments conducted for a period of 6 years after the first evaluation. We described visual profile, neuromotor development and neurological examination, cognitive profile, communication and language skills and behavioral characteristics. The GPR143 gene analysis was performed as well.
RESULTS
Children presented a variable combination of ocular and oculomotor disorders unchanged during the follow-up, a deficit in visual acuity and in contrast sensitivity that progressively improved. Abnormalities in pattern visual evoked potential were found. No deficits were detected at neurological examination and neuromotor development except for a mild impairment in hand-eye coordination observed in five cases. A language delay was observed in five cases, two of whom had also a developmental quotient delay at 2 years evolving to a borderline/deficit cognitive level at preschool age, difficulties in adaptive behavior and autistic-like features were found. Mutations in the GPR143 gene were identified in the two patients who presented the most severe clinical phenotype.
CONCLUSION
Children with OA may share, in addition to a variable combination of ocular signs and symptoms, a neurodevelopment impairment regarding mostly the cognitive, communicative, and social area, especially those with GPR143 mutation.
Topics: Albinism, Ocular; Child, Preschool; Evoked Potentials, Visual; Eye Proteins; Humans; Membrane Glycoproteins; Retrospective Studies
PubMed: 34327695
DOI: 10.1055/s-0041-1732430 -
Investigative Ophthalmology & Visual... Jul 2023The aim of this systematic review was to investigate the available data on the epidemiology of oculocutaneous albinism (OCA) around the world, and to determine whether a...
PURPOSE
The aim of this systematic review was to investigate the available data on the epidemiology of oculocutaneous albinism (OCA) around the world, and to determine whether a generalizable, worldwide prevalence figure could be proposed.
METHODS
Extensive literature search strategies were conducted, interrogating PubMed, Scopus, and Web of Science, to locate relevant literature. Ultimately 34 studies reporting original data were included for analysis.
RESULTS
Findings showed that most data were outdated, and only 6 of 34 articles (18%) were published after 2010. There were few good studies with sound methodology and large, clearly defined population samples. Only a small proportion of countries worldwide (26/193 [13%]) have produced prevalence figures for OCA. By continent, African studies were disproportionately represented (15/34 [44%]). The highest prevalence rates (range, 1 in 22 to 1 in 1300; mean, 1 in 464) were reported in population isolates. The mean prevalence from four African countries was 1 in 4264 (range, 1 in 1755 to 1 in 7900). Prevalence for three countries in Europe (mean, 1 in 12,000; range, 1 in 10,000 to 1 in 15,000) may be underestimated, as the phenotype, in fair-skinned populations, may be missed or misdiagnosed as ocular albinism or isolated visual impairment. Population rates may vary depending on local cultural factors (e.g., consanguineous matings) and may change over time.
CONCLUSIONS
The prevalence of OCA varies widely between continents and population groups, and it is often influenced by local factors. It was not possible, therefore, to determine a single, generalizable worldwide prevalence rate for OCA, although continental rates for Africa and Europe are useful.
Topics: Humans; Mutation; Prevalence; Albinism, Oculocutaneous; Phenotype; Albinism, Ocular
PubMed: 37440261
DOI: 10.1167/iovs.64.10.14