A Novel Ornithine Aminotransferase Splice Site Mutation Causes Vitamin B6-Responsive Gyrate Atrophy.

Purpose: Gyrate atrophy of the choroid and retina (GACR) is a rare congenital disorder and mutations in the ornithine aminotransferase (OAT) gene has been specified as the underlying cause. Patients show a high level of ornithine in body fluids which may be controlled by low protein diets. Pyridoxine (vitamin B6) supplementation may also be effective, however, most patients appear to be nonresponsive to this modality of treatment. Case Report: Here, we report a characterized case of a vitamin B6-responsive GACR who had a splicing mutation in the OAT gene. The GACR diagnosis was confirmed through the clinical features, imaging, biochemical findings, and whole-exome sequencing (WES) results. WES data revealed the splicing mutation in intron 4 of the OAT gene (NM_001322967: c.425-1G>A). Conclusion: Our knowledge about the diagnosis and treatment of GACR can be improved by identifying novel mutations in the OAT gene and accurate follow-up of the patients to determine how they respond to treatment.

Regression of treatment-resistant gyrate atrophy-associated intraretinal cystic spaces using long-term diet restriction: A case report.

PURPOSE: Gyrate atrophy of the choroid and retina (GA) is a rare genetic ophthalmologic condition which primarily manifests in childhood. It is characterized by hyperornithinemia and progressive chorioretinal atrophy. Patients may develop macular intraretinal cystic spaces (ICS) for which various treatment modalities have been reported. We report a patient who failed to demonstrate visual or anatomic improvement following multiple treatments for GA-associated ICS but showed improvement following prolonged dietary modification and vitamin supplementation. CASE DESCRIPTION: A 6-year-old male patient presented with previously undiagnosed GA associated with ICS. He received 6 consecutive monthly intravitreal bevacizumab injections as well as topical nepafenac and dorzolamide for treatment of ICS without significant change detected by optical coherence tomography (OCT) following treatment. He was also maintained on an arginine restricted diet with vitamin B6 supplementation. Over the course of the ensuing year, the patient was lost to follow-up due to the coronavirus disease 2019 pandemic. When he returned, his vision was stable, and OCT showed regression of the ICS. His mother reported that he had continued only on dietary restriction and vitamin B6 supplementation with no other medications or interventions. Plasma ornithine level measurement confirmed dietary compliance. Further follow-up showed continued stabilization of the condition. CONCLUSION: In addition to retarding progressive chorioretinal atrophy, prolonged dietary modifications may result in improvement of treatment-resistant GA-associated ICS. Parents' education on the value of dietary modifications for patients with GA is highly recommended.

Molecular and Cellular Studies Reveal Folding Defects of Human Ornithine Aminotransferase Variants Associated With Gyrate Atrophy of the Choroid and Retina.

The deficit of human ornithine aminotransferase (hOAT) is responsible for gyrate atrophy (GA), a rare recessive inherited disorder. Although more than 60 disease-associated mutations have been identified to date, the molecular mechanisms explaining how each mutation leads to the deficit of OAT are mostly unknown. To fill this gap, we considered six representative missense mutations present in homozygous patients concerning residues spread over the hOAT structure. E. coli expression, spectroscopic, kinetic and bioinformatic analyses, reveal that the R154L and G237D mutations induce a catalytic more than a folding defect, the Q90E and R271K mutations mainly impact folding efficiency, while the E318K and C394Y mutations give rise to both folding and catalytic defects. In a human cellular model of disease folding-defective variants, although at a different extent, display reduced protein levels and/or specific activity, due to increased aggregation and/or degradation propensity. The supplementation with Vitamin B6, to mimic a treatment strategy available for GA patients, does not significantly improve the expression/activity of folding-defective variants, in contrast with the clinical responsiveness of patients bearing the E318K mutation. Thus, we speculate that the action of vitamin B6 could be also independent of hOAT. Overall, these data represent a further effort toward a comprehensive analysis of GA pathogenesis at molecular and cellular level, with important relapses for the improvement of genotype/phenotype correlations and the development of novel treatments.

A review of treatment modalities in gyrate atrophy of the choroid and retina (GACR).

Gyrate atrophy of the choroid and retina (GACR) is a rare inborn error of amino acid metabolism caused by bi-allelic variations in OAT. GACR is characterised by vision decline in early life eventually leading to complete blindness, and high plasma ornithine levels. There is no curative treatment for GACR, although several therapeutic modalities aim to slow progression of the disease by targeting different steps within the ornithine pathway. No international treatment protocol is available. We systematically collected all international literature on therapeutic interventions in GACR to provide an overview of published treatment effects. METHODS: Following the PRISMA guidelines, we conducted a systematic review of the English literature until December 22nd 2020. PubMed and Embase databases were searched for studies related to therapeutic interventions in patients with GACR. RESULTS: A total of 33 studies (n = 107 patients) met the inclusion criteria. Most studies were designed as case reports (n = 27) or case series (n = 4). No randomised controlled trials or large cohort studies were found. Treatments applied were protein-restricted diets, pyridoxine supplementation, creatine or creatine precursor supplementation, l-lysine supplementation, and proline supplementation. Protein-restricted diets lowered ornithine levels ranging from 16.0-91.2%. Pyridoxine responsiveness was reported in 30% of included mutations. Lysine supplementation decreased ornithine levels with 21-34%. Quality assessment showed low to moderate quality of the articles. CONCLUSIONS: Based primarily on case reports ornithine levels can be reduced by using a protein restricted diet, pyridoxine supplementation (variation-dependent) and/or lysine supplementation. The lack of pre-defined clinical outcome measures and structural follow-up in all included studies impeded conclusions on clinical effectiveness. Future research should be aimed at 1) Unravelling the OAT biochemical pathway to identify other possible pathologic metabolites besides ornithine, 2) Pre-defining GACR specific clinical outcome measures, and 3) Establishing an international historical cohort.

Partial regression of foveoschisis following vitamin B6 supplementary therapy for gyrate atrophy in a Chinese girl.

BACKGROUND: To report a case of genetically confirmed gyrate atrophy (GA) of choroid and retina, who showed partial regression of foveoschisis following vitamin B6 supplementary therapy. CASE PRESENTATION: A 6-year-old Chinese girl complained about night blindness and progressive decreased vision in both eyes. Her best corrected visual acuity (BCVA) was 20/63 OD and 20/100 OS. Fundus examination showed bilateral multiple, sharply demarcated, scallop-shaped chorioretinal atrophy areas in the midperipheral and peripheral of the fundus. Spectral domain optical coherence tomography (SD-OCT) showed increased central macular thickness (CMT) with multiple intraretinal cystic spaces in the both eyes. There was no leakage or staining in the macular area in late phase of fluorescein angiography (FA). Blood tests confirmed hyperornithinemia and genetic analysis revealed two heterozygous mutations on ornithine aminotransferase (OAT) gene. Based on clinical presentation and genetic test, the patient was diagnosed as GA of the choroid and retina and further treated with vitamin B6 supplementary for three weeks. Her serum ornithine levels did not change but CMT on SD-OCT declined with partial regression of intraretinal cystic spaces. Then, the patient discontinued the drug because of severe muscle pain, and foveoschisis increased to initial level a month later. CONCLUSIONS: Foveoschisis is a rare complication of GA. Vitamin B6 supplementation may alleviate foveoschisis, but its effort for reducing serum ornithine level might be limited. Potential drug adverse effects should be noted in pediatric patients.

Multimodal characterization of a novel mutation causing vitamin B6-responsive gyrate atrophy.

PURPOSE: Gyrate atrophy (GA) is a rare chorioretinal degeneration that results in the deterioration of night and peripheral vision, eventually leading to blindness. The disorder is caused by mutations in the gene encoding ornithine aminotransferase (OAT), causing increased levels of plasma ornithine. Treatment revolves around lowering plasma ornithine levels, with vitamin B6 supplementation being the preferred treatment. Nevertheless, most patients do not respond to this therapy. Here, we report a rare case of vitamin B6-responsive GA caused by a novel mutation in OAT and characterize the presentation with multimodal imaging. METHODS: This is a single-patient case report with a clinical diagnosis based on history, multimodal retinal imaging, laboratory findings, and DNA sequencing analysis. We include a 3D structure prediction of the novel mutant protein. RESULTS: DNA sequencing analysis demonstrated that there is a homozygous, novel variant c.473A>C: p.Y158S in OAT. Upon undergoing two weeks of vitamin B6 supplementation, the patient exhibited a 28.5% reduction in plasma ornithine levels. In a follow-up visit two years later, plasma ornithine levels were reduced by 24.1% from the levels at initial presentation and disease progression was retarded based on clinical findings. CONCLUSION: One novel homozygous missense mutation in OAT was identified and considered to be pathogenic in a patient with GA. The response for the vitamin B6 supplementation was positive, which is rare in all the GA cases reported in the literature. Our data suggests that further studies regarding the relationship between genotype and responsiveness to vitamin B6 should be conducted.

Multimodal imaging of foveoschisis and macular pseudohole associated with gyrate atrophy: a family report.

BACKGROUND: To report the results of multimodal imaging of a biochemically confirmed case of a family with gyrate atrophy (GA) associated with foveoschisis and macular pseudohole. CASE PRESENTATION: Two sisters presented to us with progressive bilateral decreased vision. The 26-year old sister had a best corrected visual acuity (BCVA) of 20/32 in the right eye (RE) and 20/100 in the left eye (LE). Dilated fundus examination revealed multiple bilateral chorioretinal atrophy areas in the midperipheral and peripheral retina. Fluorescein angiography did not show any leak in the macular area. Swept-source optical coherence tomography (SS-OCT) showed increased central macular thickness in both eyes with foveoschisis. Optical coherence tomography angiography (OCTA) showed petaloid non-reflective areas and some perifoveal microvascular alterations similar to telangiectasias in the deep capillary complex. The 30-year-old sister had a BCVA of 20/20 in the RE and 20/32 in the LE. SS-OCT was normal in the RE and demonstrated a macular pseudohole with a fine epiretinal membrane in the LE. The persistent retinal tissue at the base of the pseudohole was disorganised. Blood tests showed hyperornithinemia in the 2 cases. Based on these observations, the patients were diagnosed with gyrate atrophy of the choroid and retina and were treated with a pyridoxine supplement and an arginine-restricted diet. CONCLUSIONS: Foveoschisis and macular pseudohole may be associated in GA, increasing the risk of rapid vision loss. OCTA is an interesting imaging tool that can help to better understand the pathophysiological mechanism of these macular involvements in GA.

Hiperornitinemia con atrofia gyrata de coroides y retina / Hyperornithinemia with gyrate atrophy of the choroid and retina

La atrofia gyrata de coroides y retina fue descrita por vez primera por Fuchs en el año 1896 como una entidad clínicamente definida. La deficiencia de la enzima ornitina delta aminotransferasa se hereda de forma autosómica recesiva; resulta en incremento plasmático de las concentraciones de ornitina y se asocia con atrofia gyrata de coroides y retina. Se presenta una paciente de 6 años de edad que es llevada a consulta, ya que en la escuela la maestra notaba mala visión de lejos. En un examen inicial del fondo de ojo el oftalmólogo observó cambios sugestivos de distrofia retiniana. En la oftalmoscopia binocular indirecta se encontraron extensas zonas confluentes de atrofia coroidea por fuera de las arcadas vasculares que respetaban el polo posterior; la mácula impresionaba normal. Se realizó un estudio de tomografía de coherencia óptica en dominio espectral en tomógrafo Spectralis que demostró la presencia de edema macular cistoide en ambos ojos. La determinación de niveles de ornitina en sangre arrojaron niveles muy elevados de este aminoácido (975 µmol/mL). Con todos estos hallazgos se llegó al diagnóstico de hiperornitinemia y atrofia gyrata de coroides y retina. Se indicó tratamiento dietético y vitamina B6 oral a pesar de que no se ha obtenido hasta el momento reducción significativa de los niveles de ornitina en plasma(AU)

Gyrate atrophy of the choroid and the retina was first described by Fuchs as a clinically defined condition in 1896. Human hereditary deficiency of ornithine aminotransferase activity is transmitted as an autosomal recessive trait and results in increased level of plasma ornithine and is associated with gyrate atrophy of the choroid and the retina. A 6-year-old girl was taken to the ophthalmologist's because of her far poor vision detected by her teacher at the school. In the initial eye fundus examination the ophthalmologist observed some changes indicating retinal dystrophy. The indirect binocular funduscopy revealed extensive areas of choroidal atrophy outside the vascular archades respected the posterior pole whereas the macula impressed as normal. Cystoid macular edema was evident in both eyes according to the results of the optic coherence tomography performed with Spectralis tomograph. The aminoacid analysis revealed high serum ornithine level (975 µmol/mL). The clinical diagnosis of the patient was consistent with hyper-ornithinemia and gyrate atrophy of the choroid and the retina. She was treated with vitamin B6 and dietary supplementation but no significant reduction on her serum ornithine level was observed(AU)

Hiperornitinemia con atrofia gyrata de coroides y retina / Hyperornithinemia with gyrate atrophy of the choroid and retina

La atrofia gyrata de coroides y retina fue descrita por vez primera por Fuchs en el año 1896 como una entidad clínicamente definida. La deficiencia de la enzima ornitina delta aminotransferasa se hereda de forma autosómica recesiva; resulta en incremento plasmático de las concentraciones de ornitina y se asocia con atrofia gyrata de coroides y retina. Se presenta una paciente de 6 años de edad que es llevada a consulta, ya que en la escuela la maestra notaba mala visión de lejos. En un examen inicial del fondo de ojo el oftalmólogo observó cambios sugestivos de distrofia retiniana. En la oftalmoscopia binocular indirecta se encontraron extensas zonas confluentes de atrofia coroidea por fuera de las arcadas vasculares que respetaban el polo posterior; la mácula impresionaba normal. Se realizó un estudio de tomografía de coherencia óptica en dominio espectral en tomógrafo Spectralis que demostró la presencia de edema macular cistoide en ambos ojos. La determinación de niveles de ornitina en sangre arrojaron niveles muy elevados de este aminoácido (975 µmol/mL). Con todos estos hallazgos se llegó al diagnóstico de hiperornitinemia y atrofia gyrata de coroides y retina. Se indicó tratamiento dietético y vitamina B6 oral a pesar de que no se ha obtenido hasta el momento reducción significativa de los niveles de ornitina en plasma(AU)

Gyrate atrophy of the choroid and the retina was first described by Fuchs as a clinically defined condition in 1896. Human hereditary deficiency of ornithine aminotransferase activity is transmitted as an autosomal recessive trait and results in increased level of plasma ornithine and is associated with gyrate atrophy of the choroid and the retina. A 6-year-old girl was taken to the ophthalmologist’s because of her far poor vision detected by her teacher at the school. In the initial eye fundus examination the ophthalmologist observed some changes indicating retinal dystrophy. The indirect binocular funduscopy revealed extensive areas of choroidal atrophy outside the vascular archades respected the posterior pole whereas the macula impressed as normal. Cystoid macular edema was evident in both eyes according to the results of the optic coherence tomography performed with Spectralis tomograph. The aminoacid analysis revealed high serum ornithine level (975 µmol/mL). The clinical diagnosis of the patient was consistent with hyper-ornithinemia and gyrate atrophy of the choroid and the retina. She was treated with vitamin B6 and dietary supplementation but no significant reduction on her serum ornithine level was observed(AU)

Reversal of cystoid macular edema in gyrate atrophy patients.

PURPOSE: This study reports the presentation of two families with gyrate atrophy (GA). The aim of this study was to characterize the potential effect of therapeutic regimens on macular edema. METHODS: Two unrelated patients with GA were studied for the potential effect of low protein diet (≤ 0.8 g/kg/d), and oral administration of pyridoxine (500 mg/day), on serum ornithine levels, best corrected visual acuity (BCVA), slit-lamp, OCT, and auto-fluorescence findings. Blood samples for DNA, mRNA, and exons of the OAT gene were screened for mutations and splicing effect when relevant. RESULTS: At presentation, both patients manifested typical ophthalmic features of GA including cystoid macular edema (CME). One patient also exhibited optic nerve head hamartoma. Following treatment ornithine levels have lessened, BCVA improved, and central macular thickness (CMT) markedly decreased in all four studied eyes. The molecular pathologic features included a novel splice site mutation (c.900+1G>A). CONCLUSIONS: We have identified a novel mutation and two formerly described mutations in patients with GA. Of them, one patient comprised an unusual phenotype including bilateral astrocytic hamartomas. We have recognized for the first time improvement in CME following treatment with low protein intake and pyridoxine supplement. This finding may have significance in the understanding of treatment options for macular edema regardless of underlying etiology.

Gyrate atrophy of the choroid and retina diagnosed by ornithine-δ-aminotransferase gene analysis: a case report.

A pair of 19-year-old female identical twins was referred to our hospital with progressive visual loss. They exhibited bilateral chorioretinal atrophy involving the midperiphery on fundoscopy and fluorescein angiography. Bilateral visual field constriction was noted on dynamic Goldmann perimetry, and a markedly impaired response was observed on both photopic and scotopic electroretinograms. Cystoid macular edema was identified in both eyes on optical coherence tomography. Plasma levels of ornithine were elevated. Based on these observations, the patients were diagnosed with gyrate atrophy of the choroid and retina. The clinical diagnosis was confirmed by mutation analysis of the ornithine-δ-aminotransferase (OAT) gene. Patients were treated with a pyridoxine supplement (300 mg/day) and an arginine-restricted diet to lower plasma levels of ornithine, which were successfully reduced without progression of chorioretinal atrophy for 15 months. Our report describes the first case of gyrate atrophy in the Korean population diagnosed by OAT gene analysis and treated with vitamin B6 dietary supplementation.

Gyrate Atrophy of the Choroid and Retina Diagnosed by Ornithine-delta-aminotransferase Gene Analysis: A Case Report

A pair of 19-year-old female identical twins was referred to our hospital with progressive visual loss. They exhibited bilateral chorioretinal atrophy involving the midperiphery on fundoscopy and fluorescein angiography. Bilateral visual field constriction was noted on dynamic Goldmann perimetry, and a markedly impaired response was observed on both photopic and scotopic electroretinograms. Cystoid macular edema was identified in both eyes on optical coherence tomography. Plasma levels of ornithine were elevated. Based on these observations, the patients were diagnosed with gyrate atrophy of the choroid and retina. The clinical diagnosis was confirmed by mutation analysis of the ornithine-delta-aminotransferase (OAT) gene. Patients were treated with a pyridoxine supplement (300 mg/day) and an arginine-restricted diet to lower plasma levels of ornithine, which were successfully reduced without progression of chorioretinal atrophy for 15 months. Our report describes the first case of gyrate atrophy in the Korean population diagnosed by OAT gene analysis and treated with vitamin B6 dietary supplementation.

Gyrate atrophy of choroid and retina with myopia, cataract and systemic proximal myopathy: A rare case report from rural India.

Gyrate atrophy is a rare metabolic disease with autosomal recessive inheritance pattern characterised by hyperornithinemia and typical ocular findings. This report presents a 17-year-old intellectually challenged girl consulting for a progressive fall of visual acuity with night blindness. Fundus examination showed patches of chorioretinal atrophy with typical scalloped borders and peri vascular pigmentation in the equatorial region. Fundus fluroscein angiography revealed characteristic staining pattern. Other ocular associations included myopia and posterior sub capsular cataract. Progressive systemic proximal myopathy was one of the associated features. Dietary supplementation of vitamin B6 was advised.