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Case Report: Ophthalmologic Evaluation Over a Long Follow-Up Time in a Patient With Wolfram Syndrome Type 2: Slowly Progressive Optic Neuropathy as a Possible Clinical Finding.

ABSTRACT: Wolfram syndrome (WFS) is a rare autosomal recessive neurodegenerative disease whose diagnosis requires diabetes mellitus and optic atrophy (OA). WFS includes a wide spectrum of other possible complications such as diabetes insipidus, sensorineural deafness, urinary tract problems, neurological and psychiatric disorders. Most WFS patients show type 1 syndrome (WFS1) caused by mutations in the WFS1 gene, encoding Wolframin protein, while few patients are affected by WFS type 2 (WFS2) due to a pathogenetic variants in the CISD2 gene encoding an endoplasmic reticulum intermembrane small protein. WFS2 is considered a phenotypic and genotypic variant of WFS, from which differs only for the increased risk of bleeding and presence of peptic ulcers. OA and diabetes are considered cardinal features of WFS. We hereby report the ophthalmologic evaluation in a patient, previously described, with WFS2 after 8 years of follow-up. A 20-year-old white woman was referred to our retinal center for the first time in 2012 following a diagnosis of a novel intragenic exon 2 CISD2 homozygous deletion, for the suspicion of an associated bilateral OA. Fundus examination, spectral-domain optical coherence tomography, visual field, visual evoked potentials were performed and confirmed the presence of an optic neuropathy that remained stable over 8 years follow up. A slowly progressive optic neuropathy, rather than OA can characterize patients with WFS2 and CISD2 intragenic deletion.

SUBMITTER: Di Iorio V

PROVIDER: S-EPMC8116581 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BackgroundWolfram Syndrome type 2 (WFS2) is considered a phenotypic and genotypic variant of WFS, whose minimal criteria for diagnosis are diabetes mellitus and optic atrophy. The disease gene for WFS2 is CISD2. The clinical phenotype of WFS2 differs from WFS1 for the absence of diabetes insipidus and psychiatric disorders, and for the presence of bleeding upper intestinal ulcers and defective platelet aggregation. After the first report of consanguineous Jordanian patients, no further cases of WFS2 have been reported worldwide. We describe the first Caucasian patient affected by WFS2.Case presentationThe proband was a 17 year-old girl. She presented diabetes mellitus, optic neuropathy, intestinal ulcers, sensorineural hearing loss, and defective platelet aggregation to ADP. Genetic testing showed a novel homozygous intragenic deletion of CISD2 in the proband. Her brother and parents carried the heterozygous mutation and were apparently healthy, although they showed subclinical defective platelet aggregation. Long runs of homozygosity analysis from SNP-array data did not show any degree of parental relationship, but the microsatellite analysis confirmed the hypothesis of a common ancestor.ConclusionOur patient does not show optic atrophy, one of the main diagnostic criteria for WFS, but optic neuropathy. Since the "asymptomatic" optic atrophy described in Jordanian patients is not completely supported, we could suppose that the ocular pathology in Jordanian patients was probably optic neuropathy and not optic atrophy. Therefore, as optic atrophy is required as main diagnostic criteria of WFS, it might be that the so-called WFS2 could not be a subtype of WFS. In addition, we found an impaired aggregation to ADP and not to collagen as previously reported, thus it is possible that different experimental conditions or inter-patient variability can explain different results in platelet aggregation. Further clinical reports are necessary to better define the clinical spectrum of this syndrome and to re-evaluate its classification.

Project description:Wolfram syndrome (WS) is a rare childhood disease characterized by diabetes mellitus, diabetes insipidus, blindness, deafness, neurodegeneration and eventually early death, due to autosomal recessive mutations in the WFS1 (and WFS2) gene. While it is categorized as a neurodegenerative disease, it is increasingly becoming clear that other cell types besides neurons may be affected and contribute to the pathogenesis. MRI studies in patients and phenotyping studies in WS rodent models indicate white matter/myelin loss, implicating a role for oligodendroglia in WS-associated neurodegeneration. In this study, we sought to determine if oligodendroglia are affected in WS and whether their dysfunction may be the primary cause of the observed optic neuropathy and brain neurodegeneration. We demonstrate that 7.5-month-old Wfs1∆exon8 mice display signs of abnormal myelination and a reduced number of oligodendrocyte precursor cells (OPCs) as well as abnormal axonal conduction in the optic nerve. An MRI study of the brain furthermore revealed grey and white matter loss in the cerebellum, brainstem, and superior colliculus, as is seen in WS patients. To further dissect the role of oligodendroglia in WS, we performed a transcriptomics study of WS patient iPSC-derived OPCs and pre-myelinating oligodendrocytes. Transcriptional changes compared to isogenic control cells were found for genes with a role in ER function. However, a deep phenotyping study of these WS patient iPSC-derived oligodendroglia unveiled normal differentiation, mitochondria-associated endoplasmic reticulum (ER) membrane interactions and mitochondrial function, and no overt signs of ER stress. Overall, the current study indicates that oligodendroglia functions are largely preserved in the WS mouse and patient iPSC-derived models used in this study. These findings do not support a major defect in oligodendroglia function as the primary cause of WS, and warrant further investigation of neurons and neuron-oligodendroglia interactions as a target for future neuroprotective or -restorative treatments for WS.

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Case Report: Ophthalmologic Evaluation Over a Long Follow-Up Time in a Patient With Wolfram Syndrome Type 2: Slowly Progressive Optic Neuropathy as a Possible Clinical Finding.

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