Anti-MOG-associated demyelinating disorders: two sides of the same coin.

BACKGROUND: Anti-myelin oligodendrocyte glycoprotein antibody-associated disorders (MOGAD) are new emerging diseases with heterogeneous course, treatment, response, and prognosis. CASE REPORT: We herein present 2 cases with antibodies to MOG, one with a cerebellar/brainstem monophasic syndrome which partially improved after treatment, and the other with an optic neuritis onset then relapsed with cortical encephalitis and presented a subsequent complete recovery. We further discuss elements possibly associated with disease heterogeneity and influencing treatment choices. CONCLUSIONS: MOGAD is an extremely variable disease which can relapse and accumulate disability over time. An early diagnosis and correct timely treatment is fundamental to improve clinical outcome.

Optic neuritis of MOG-IgG-associated autoimmune disorders: a case report.

BACKGROUND: The diagnosis of immunoglobulin G serum antibodies to myelin oligodendrocyte glycoprotein (MOG-IgG) associated inflammatory demyelinating disorders can be confirmed by the presence of MOG-IgG, yet its general cut-off concentration had not yet to be defined. Whether it is significant that a seropositive lower titer level for MOG-IgG could cause disease is still unknown. CASE PRESENTATION: A 55-year-old Chinese woman presented with acute optic neuritis manifestations in the left eye. MRI showed a left optic nerve demyelination image and a T2 hyperintensity at C7 vertebral segment without any extra specific lesions. AQP4-IgG was tested seronegative, while the MOG-IgG was positive, titer 1:10, by indirect immunofluorescence. Considering the lower concentration, we retested serum MOG-IgG after 6 months of steroid therapy, using cell-based assay, then we still got the same result which was also barely above the negative cut-off value. So, the clinical diagnose was "possible MOG-IgG-associated encephalomyelitis". The woman's condition improved by steroid therapy without relapse. CONCLUSIONS: Seropositive MOG-IgG, even at a lower level, could lead to an autoimmune inflammatory demyelination. In adults, it commonly presents as ON and myelitis. Although the patient had a considerable reaction, steroid therapy could not make MOG-IgG seronegative, instead, the antibody may persist even during remission and flare-ups can recur after steroid withdrawal. Therefore, a long-term follow-up is necessary to monitor the patient's prognosis.

The history of neuromyelitis optica. Part 2: 'Spinal amaurosis', or how it all began.

Neuromyelitis optica (NMO) was long considered a clinical variant of multiple sclerosis (MS). However, the discovery of a novel and pathogenic anti-astrocytic serum autoantibody targeting aquaporin-4 (termed NMO-IgG or AQP4-Ab), the most abundant water channel protein in the central nervous system, led to the recognition of NMO as a distinct disease entity in its own right and generated strong and persisting interest in the condition. NMO is now studied as a prototypic autoimmune disorder, which differs from MS in terms of immunopathogenesis, clinicoradiological presentation, optimum treatment, and prognosis. While the history of classic MS has been extensively studied, relatively little is known about the history of NMO. In Part 1 of this series we focused on the late 19th century, when the term 'neuromyelitis optica' was first coined, traced the term's origins and followed its meandering evolution throughout the 20th and into the 21st century. Here, in Part 2, we demonstrate that the peculiar concurrence of acute optic nerve and spinal cord affliction characteristic for NMO caught the attention of physicians much earlier than previously thought by re-presenting a number of very early cases of possible NMO that date back to the late 18th and early 19th century. In addition, we comprehensively discuss the pioneering concept of 'spinal amaurosis', which was introduced into the medical literature by ophthalmologists in the first half of the 19th century.

MOG encephalomyelitis: international recommendations on diagnosis and antibody testing.

Over the past few years, new-generation cell-based assays have demonstrated a robust association of autoantibodies to full-length human myelin oligodendrocyte glycoprotein (MOG-IgG) with (mostly recurrent) optic neuritis, myelitis and brainstem encephalitis, as well as with acute disseminated encephalomyelitis (ADEM)-like presentations. Most experts now consider MOG-IgG-associated encephalomyelitis (MOG-EM) a disease entity in its own right, immunopathogenetically distinct from both classic multiple sclerosis (MS) and aquaporin-4 (AQP4)-IgG-positive neuromyelitis optica spectrum disorders (NMOSD). Owing to a substantial overlap in clinicoradiological presentation, MOG-EM was often unwittingly misdiagnosed as MS in the past. Accordingly, increasing numbers of patients with suspected or established MS are currently being tested for MOG-IgG. However, screening of large unselected cohorts for rare biomarkers can significantly reduce the positive predictive value of a test. To lessen the hazard of overdiagnosing MOG-EM, which may lead to inappropriate treatment, more selective criteria for MOG-IgG testing are urgently needed. In this paper, we propose indications for MOG-IgG testing based on expert consensus. In addition, we give a list of conditions atypical for MOG-EM ("red flags") that should prompt physicians to challenge a positive MOG-IgG test result. Finally, we provide recommendations regarding assay methodology, specimen sampling and data interpretation.

[MOG encephalomyelitis: international recommendations on diagnosis and antibody testing]. / MOG-Enzephalomyelitis: Internationale Empfehlungen zu Diagnose und Antikörpertestung.

Over the past few years, new-generation cell-based assays have demonstrated a robust association of autoantibodies to full-length human myelin oligodendrocyte glycoprotein (MOG-IgG) with (mostly recurrent) optic neuritis, myelitis and brainstem encephalitis, as well as with acute disseminated encephalomyelitis (ADEM)-like presentations. Most experts now consider MOG-IgG-associated encephalomyelitis (MOG-EM) a disease entity in its own right, immunopathogenetically distinct from both classic multiple sclerosis (MS) and aquaporin-4 (AQP4)-IgG-positive neuromyelitis optica spectrum disorders (NMOSD). Owing to a substantial overlap in clinicoradiological presentation, MOG-EM was often unwittingly misdiagnosed as MS in the past. Accordingly, increasing numbers of patients with suspected or established MS are currently being tested for MOG-IgG. However, screening of large unselected cohorts for rare biomarkers can significantly reduce the positive predictive value of a test. To lessen the hazard of overdiagnosing MOG-EM, which may lead to inappropriate treatment, more selective criteria for MOG-IgG testing are urgently needed. In this paper, we propose indications for MOG-IgG testing based on expert consensus. In addition, we give a list of conditions atypical for MOG-EM ("red flags") that should prompt physicians to challenge a positive MOG-IgG test result. Finally, we provide recommendations regarding assay methodology, specimen sampling and data interpretation, and propose for the first time diagnostic criteria for MOG-EM.

MOG-IgG in NMO and related disorders: a multicenter study of 50 patients. Part 3: Brainstem involvement - frequency, presentation and outcome.

BACKGROUND: Myelin oligodendrocyte glycoprotein antibodies (MOG-IgG) are present in a subset of aquaporin-4 (AQP4)-IgG-negative patients with optic neuritis (ON) and/or myelitis. Little is known so far about brainstem involvement in MOG-IgG-positive patients. OBJECTIVE: To investigate the frequency, clinical and paraclinical features, course, outcome, and prognostic implications of brainstem involvement in MOG-IgG-positive ON and/or myelitis. METHODS: Retrospective case study. RESULTS: Among 50 patients with MOG-IgG-positive ON and/or myelitis, 15 (30 %) with a history of brainstem encephalitis were identified. All were negative for AQP4-IgG. Symptoms included respiratory insufficiency, intractable nausea and vomiting (INV), dysarthria, dysphagia, impaired cough reflex, oculomotor nerve palsy and diplopia, nystagmus, internuclear ophthalmoplegia (INO), facial nerve paresis, trigeminal hypesthesia/dysesthesia, vertigo, hearing loss, balance difficulties, and gait and limb ataxia; brainstem involvement was asymptomatic in three cases. Brainstem inflammation was already present at or very shortly after disease onset in 7/15 (47 %) patients. 16/21 (76.2 %) brainstem attacks were accompanied by acute myelitis and/or ON. Lesions were located in the pons (11/13), medulla oblongata (8/14), mesencephalon (cerebral peduncles; 2/14), and cerebellar peduncles (5/14), were adjacent to the fourth ventricle in 2/12, and periaqueductal in 1/12; some had concomitant diencephalic (2/13) or cerebellar lesions (1/14). MRI or laboratory signs of blood-brain barrier damage were present in 5/12. Cerebrospinal fluid pleocytosis was found in 11/14 cases, with neutrophils in 7/11 (3-34 % of all CSF white blood cells), and oligoclonal bands in 4/14. Attacks were preceded by acute infection or vaccination in 5/15 (33.3 %). A history of teratoma was noted in one case. The disease followed a relapsing course in 13/15 (87 %); the brainstem was involved more than once in 6. Immunosuppression was not always effective in preventing relapses. Interferon-beta was followed by new attacks in two patients. While one patient died from central hypoventilation, partial or complete recovery was achieved in the remainder following treatment with high-dose steroids and/or plasma exchange. Brainstem involvement was associated with a more aggressive general disease course (higher relapse rate, more myelitis attacks, more frequently supratentorial brain lesions, worse EDSS at last follow-up). CONCLUSIONS: Brainstem involvement is present in around one third of MOG-IgG-positive patients with ON and/or myelitis. Clinical manifestations are diverse and may include symptoms typically seen in AQP4-IgG-positive neuromyelitis optica, such as INV and respiratory insufficiency, or in multiple sclerosis, such as INO. As MOG-IgG-positive brainstem encephalitis may take a serious or even fatal course, particular attention should be paid to signs or symptoms of additional brainstem involvement in patients presenting with MOG-IgG-positive ON and/or myelitis.

Myelin Oligodendrocyte Glycoprotein Antibody-Associated Disease: A Case Report.

Myelin oligodendrocyte glycoprotein antibody-associated disease (MOGAD) is a newly discovered autoimmune demyelinating disorder. The clinical manifestations of MOGAD are divergent but often characterized by inflammatory central nervous system (CNS) deficits such as optic neuritis, encephalitis, or transverse myelitis that predominantly affect the pediatric population. Despite the distinct features often associated with MOGAD, the disease exhibits a diverse range of clinical manifestations, making timely diagnosis and treatment challenging. In particular, distinguishing MOGAD from multiple sclerosis (MS) is important for adequate treatment and the prevention of relapsing disease. In this report, we present a rare case of MOGAD in a 57-year-old male who initially exhibited symptoms of bilateral optic nerve edema and flame hemorrhage. This led to an initial misdiagnosis of pseudotumor cerebri. Serological analysis at a tertiary care center ultimately led to the diagnosis of MOGAD after multiple visits to the ophthalmologist with worsening vision deficits.

Navigating the Uncharted Territory of Pediatric-Onset Multiple Sclerosis in a 12-Year-Old Male: A Case Study.

This case report presents an atypical instance of pediatric-onset multiple sclerosis (MS) in a 12-year-old male, a demographic less commonly affected by this condition. The patient's clinical course was marked by severe and progressive symptoms, including lower limb weakness and loss of bowel/bladder control, diverging from the typical relapsing-remitting pattern observed in pediatric MS. Despite initial resistance to high-dose steroid treatment, his condition was ultimately stabilized through plasmapheresis, following the detection of myelin oligodendrocyte glycoprotein antibodies. Unique aspects of this case included the patient's young age, male gender, and the occurrence of osteopenia, as identified by a dual-energy X-ray absorptiometry scan. This report highlights the variability in MS presentations among pediatric patients and underscores the importance of a personalized, multidisciplinary approach to diagnosis and treatment. It contributes to the growing body of knowledge on pediatric MS, emphasizing the need for heightened clinical vigilance and tailored management strategies in young patients with this complex and lifelong disease.

Unilateral Autoimmune Encephalitis: A Case Report on a Rare Manifestation of Myelin Oligodendrocyte Glycoprotein Antibody Disease.

Myelin oligodendrocyte glycoprotein (MOG)-associated disease (MOGAD) is a rare, antibody-mediated inflammatory demyelinating disorder of the central nervous system (CNS) that has varying phenotypes. FLAIR (fluid-attenuated inversion recovery)-hyperintense Lesions in Anti-MOG-associated Encephalitis with Seizures (FLAMES) is a much rarer manifestation of cortical encephalitis encountered in MOGAD. We report a rare case of a nine-year-old girl who presented with a drop in her academic performance and right-sided Epilepsia partialis continua. Magnetic resonance imaging (MRI) of the brain detected evidence for unilateral (left) cortical encephalitis with peri-ictal juxtacortical edema. An electroencephalogram revealed a hemi-generalized poly spike and wave discharges in the left hemisphere, several of which correlated with myoclonic jerks. The cerebrospinal fluid (CSF) analysis was normal. Autoimmune workup resulted in a positive serum MOG-immunoglobulin G (IgG), which confirmed the diagnosis of FLAMES. The child showed an excellent clinical response to intravenous methylprednisolone and intravenous immunoglobulins therapy.

Combined Central and Peripheral Demyelination in a Patient of Multifocal Motor Neuropathy and Positive Anti-myelin Oligodendrocyte Glycoprotein (MOG) Antibodies.

Myelin oligodendrocyte glycoprotein (MOG) antibodies have been identified in central nervous system inflammatory demyelinating disorders (MOG antibody disease), inclusive of optic neuritis, transverse myelitis, or acute disseminated encephalomyelitis. The association of MOG antibodies with combined central and peripheral demyelination (CCPD) is not clear. It has been reported in a few cases where MOG antibodies were detected in the serum of patients with chronic inflammatory demyelinating polyneuropathy. However, multifocal motor neuropathy with MOG antibodies is extremely rare. We present a patient who had clinical, neurophysiological, radiological, and biochemical findings that support the diagnosis of CCPD (multifocal motor neuropathy and cord lesion) with MOG antibodies. The patient was treated with a combination therapy of intravenous immunoglobulins plus high-dose methylprednisolone, which resulted in significant improvement.

Self-remitting cerebral cortical encephalitis associated with myelin oligodendrocyte glycoprotein antibody mimicking acute viral encephalitis: A case report.

A 22-year-old woman acutely developed recurrent convulsive seizures followed by fever and headache. Cerebrospinal fluid study showed leukocytosis without hypoglycorrhachia. These clinical features suggested acute viral or aseptic encephalitis. The patient was treated only with an antiviral agent and improved immediately with good prognosis. Afterwards, the characteristic brain MRI findings required us to check the patient's serum, and the final diagnosis of myelin oligodendrocyte glycoprotein (MOG) antibody-positive cerebral cortical encephalitis (CCE) was confirmed. Most previously reported cases with MOG antibody-positive CCE clinically showed fever and/or headache, and some were initially misdiagnosed of having central nervous system infection. All previously reported cases were treated with immunotherapy. However, our case showed the very benign clinical course and improved rapidly without any immunotherapy. We should be reminded that MOG-antibody-positive CCE could be self-remitting and mimic acute viral or aseptic encephalitis. In addition, the characteristic neuroradiological findings could be an important clue to the correct diagnosis of CCE.

Myelin Oligodendrocyte Glycoprotein (MOG) Antibody Positive Patients in a Multi-Ethnic Canadian Cohort.

Introduction: Myelin oligodendrocyte glycoprotein (MOG) antibody-associated disease is a recently described central nervous system (CNS) inflammatory disorder with phenotypic overlap with Neuromyelitis Optica Spectrum Disorder (NMOSD). NMOSD seronegative patients, and those with limited forms of the disorder, become suspects for MOG antibody-associated disease. We describe a multi-ethnic population with MOG antibody seropositivity from the University of British Columbia MS/NMO clinic. Methods: AQP4-antibody seronegative patients presenting 2005-2016 with CNS inflammatory disease suspicious for NMOSD, as well as 20 MS controls, were retrospectively tested for MOG-IgG1 antibodies by live cell-based assay at Oxford Autoimmune Neurology Diagnostic Laboratory (UK) and by a commercial fixed cell-based assay at MitogenDx (Calgary, Canada). Additional MOG seropositive cases were identified through routine clinical interaction (2016-2018) using one of these laboratories. Clinical data was reviewed retrospectively. Results: Retrospective testing identified 21 MOG seropositives (14 by live assay only, 3 by fixed assay only and 4 by both) representing 14% of the "NMOSD suspects" cohort. One multiple sclerosis (MS) control serum was MOG seropositive. Twenty additional MOG positive cases were identified prospectively. Of 42 patients (27 female), median disease onset age was 29 years (range 3-62; 9 pediatric cases), 20 (47%) were non-Caucasian, and 3 (7%) had comorbid autoimmune disease. Most common onset phenotypes were optic neuritis (23, 55%; 8 bilateral) and myelitis (9, 21%; 6 longitudinally extensive) Three of the patients in our cohort experienced cortical encephalitis; two presented with seizures. Onset was moderate-severe in 64%, but 74% had good response to initial steroid therapy. Cumulative relapse probability for the MOG positive group at 1 year was 0.428 and at 4 years was 0.628. Most had abnormal brain imaging, including cortical encephalitis and poorly demarcated subcortical and infratentorial lesions. Few "classic MS" lesions were seen. Optic nerve lesions (frequently bilateral) were long and predominantly anterior, but 5 extended to the chiasm. Spinal cord lesions were long and short, with involvement of multiple spinal regions simultaneously, including the conus medullaris. Conclusions: Our MOG seropositive patients display phenotypes similar to previous descriptions, including cortical lesions with seizures and conus medullaris involvement. Many patients relapsed, predominantly in a different CNS location from onset. Serologic data from two different cell-based antibody assays highlight the discrepancies between live and fixed testing for MOG antibodies.

Late-onset neutropenia after RITUXIMAB therapy for multiple sclerosis, neuromyelitis optica spectrum disorders and MOG-antibody-associated diseases.

Few cases of late onset neutropenia after RITUXIMAB treatment (LONART) have been reported in patients with neuroinflammatory disorders. We conducted a retrospective analysis of patients treated with RITUXIMAB for neuromyelitis optica spectrum disorders (NMOSD), MOG-antibody-associated disease (MOGAD) and multiple sclerosis (MS) at the Toulouse University Hospital from November 2007 to October 2019. Ten patients with LONART were identified in a total of 385 patients: 4/25 were MOGAD patients, 2/20 were NMOSD patients and only 4/340 were MS patients (p < 0,05). Six required intravenous antibiotics whereas four were asymptomatic. Eight patients received new infusions of RITUXIMAB after resolution of their neutropenia. Neutropenia recurred in one patient.

MOG encephalomyelitis: distinct clinical, MRI and CSF features in patients with longitudinal extensive transverse myelitis as first clinical presentation.

BACKGROUND: Based on clinical, immunological and histopathological evidence, MOG-IgG-associated encephalomyelitis (MOG-EM) has emerged as a distinct disease entity different from multiple sclerosis (MS) and aquaporin-4-antibody-positive neuromyelitis optica spectrum disorder (NMOSD). MOG-EM is associated with a broader clinical phenotype including optic neuritis, myelitis, brainstem lesions and acute disseminated encephalomyelitis with a substantial clinical and radiological overlap to other demyelinating CNS disorders. OBJECTIVE: To evaluate common clinical, MRI and CSF findings, as well as therapy responses in patients with longitudinal extensive transverse myelitis (LETM) as initial clinical presentation of MOG-EM. METHODS: After excluding patients with a known diagnosis of MS, we identified 153 patients with myelitis of which 7 fulfilled the inclusion criteria and were investigated for MRI, CSF and clinical parameters. RESULTS: Patients with LETM as first clinical presentation of MOG-EM display similar characteristics, namely a lack of gadolinium-enhancement in spinal cord MRI, marked pleocytosis, negative oligoclonal bands, a previous history of infections/vaccinations and response to antibody-depleting treatments for acute attacks and long-term treatment. CONCLUSIONS: We identify common pathological findings in patients with LETM as first clinical presentation of MOG-EM which distinguishes it from other forms of LETM and should lead to testing for MOG-IgG in these cases.

[Clinical and epidemiological features in Neuromyelitis Optica Spectrum Disorder]. / Comparaison clinico-épidémiologique des pathologies du spectre des neuromyélites optiques.

INTRODUCTION: Neuromyelitis optica spectrum disorder (NMO-SD) has been recognized for the past decade. Biomarkers such as anti-Aquaporin 4 antibodies (AQP4) and anti-Myelin Oligodendrocyte Glycoprotein (MOG) have been able to classify NMO-SD into several groups. METHODS: A retrospective study was performed in the Strasbourg University Medical Center among patients with AQP4+, MOG+ and double-seronegative NMO to compare their clinical, epidemiological and paraclinical features. RESULTS: Thirty-two patients with NMO were included. The AQP4+ NMO patients had a median of age of 45 years, with associated myelitis in 62.5% of cases and other autoantibodies in 37.5% of cases. The mean number of relapses by clinical history was 3. The mean initial visual acuity during an exacerbation was 0.3 LogMAR, and the visual acuity after an exacerbation was 0.1 LogMAR. MOG+NMO patients had a median age of 23 years, with severely impaired initial visual acuity (0.6 LogMAR) but better recovery (0 LogMAR); optic disc edema was present in 80% of cases; the mean number of relapses on clinical history was 1. AQP4-/MOG- NMO's were more common in women (70%) and were bilateral in 40% of cases. CONCLUSION: The diagnostic characteristics of NMO-SD are becoming increasingly differentiated, with a positive impact on functional prognosis and long-term progression. Other biomarkers have yet to be identified to improve the diagnosis and treatment of these disorders.

Neurological update: MOG antibody disease.

Myelin oligodendrocyte glycoprotein (MOG) antibody disease (MOG-AD) is now recognised as a nosological entity with specific clinical and paraclinical features to aid early diagnosis. Although no age group is exempt, median age of onset is within the fourth decade of life, with optic neuritis being the most frequent presenting phenotype. Disease course can be either monophasic or relapsing, with subsequent relapses most commonly involving the optic nerve. Residual disability develops in 50-80% of patients, with transverse myelitis at onset being the most significant predictor of long-term outcome. Recent advances in MOG antibody testing offer improved sensitivity and specificity. To avoid misdiagnosis, MOG antibody testing should be undertaken in selected cases presenting clinical and paraclinical features that are felt to be in keeping with MOG-AD, using a validated cell-based assay. MRI characteristics can help in differentiating MOG-AD from other neuroinflammatory disorders, including multiple sclerosis and neuromyelitis optica. Cerebrospinal fluid oligoclonal bands are uncommon. Randomised control trials are limited, but observational open-label experience suggests a role for high-dose steroids and plasma exchange in the treatment of acute attacks, and for immunosuppressive therapies, such as steroids, oral immunosuppressants and rituximab as maintenance treatment.

The first Japanese report on neuromyelitis optica rediscovered: acute bilateral blindness, tetraparesis and respiratory insufficiency in a 35-year-old man (1891).

The term 'neuromyelitis optica' (NMO, Devic syndrome) is used to refer to a syndrome characterized by optic neuritis and myelitis. For many decades NMO was classified as a clinical variant of multiple sclerosis (MS). Recent research has shown, however, that NMO differs from MS in terms of immunopathogenesis, clinical presentation, and optimum treatment. In most cases, NMO is caused by autoantibodies to aquaporin-4 or myelin oligodendrocyte glycoprotein. While the history of classic MS has been studied extensively, only relatively little is known about the early history of NMO. Although NMO is considered to be much more prevalent among Asian than among European patients with CNS demyelination, all early reports of NMO reviewed by Eugène Devic and Fernand Gault in their seminal 1894 review and all other reports from the 19th century re-discovered by us over the past years related cases of NMO in patients of European descent. Here, we would like to draw the attention to an early report on NMO in a Japanese patient, published by Tanemichi Aoyama (1859-1917), one of the most eminent physicians of the Meiji period, an era characterized by a Western-style revolution in Japanese medicine. The report was published in 1891, i.e. 3 years before Devic and Gault's disease defining study on NMO. To the best of our knowledge, this is the earliest report on an Asian patient with NMO. We give an English translation of the original Japanese report written in bungo (pre-modern Japanese) and discuss the case both in the light of current knowledge on NMO and from a historical perspective.

Clinical spectrum and IgG subclass analysis of anti-myelin oligodendrocyte glycoprotein antibody-associated syndromes: a multicenter study.

Anti-myelin oligodendrocyte glycoprotein antibodies (MOG-Ab) recently emerged as a potential biomarker in patients with inflammatory demyelinating diseases of the central nervous system. We here compare the clinical and laboratory findings observed in a cohort of MOG-Ab seropositive and seronegative cases and describe IgG subclass analysis results. Consecutive serum samples referred to Verona University Neuropathology Laboratory for aquaporin-4 (AQP4)-Ab and/or MOG-Ab testing were analysed between March 2014 and May 2017. The presence of AQP4-Ab was determined using a cell-based assay. A live cell immunofluorescence assay was used for the detection of MOG-IgG and IgG subclass analysis. Among 454 analysed samples, 29 were excluded due to AQP4-Ab positivity or to the final demonstration of a disorder not compatible with MOG-Ab. We obtained clinical data in 154 out of 425 cases. Of these, 22 subjects resulted MOG-Ab positive. MOG-Ab positive patients were mainly characterised by the involvement of the optic nerve and/or spinal cord. Half of the cases presented relapses and the recovery was usually partial. Brain MRI was heterogeneous while short lesions were the prevalent observation on spinal cord MRI. MOG-Ab titre usually decreased in non-relapsing cases. In all MOG-IgG positive cases, we observed IgG1 antibodies, which were predominant in most subjects. IgG2 (5/22), IgG3 (9/22) and IgG4 (3/22) antibodies were also detectable. We confirm that MOG-Ab-related syndromes have distinct features in the spectrum of demyelinating conditions, and we describe the possible role of the different IgG subclasses in this condition.