IMPORTANCE Myelin oligodendrocyte glycoprotein antibodies (MOG-Abs) are consistently identified in a range of demyelinating disorders in adults and children. Current therapeutic strategies are largely center specific, and no treatments have been formally evaluated. OBJECTIVE To examine the clinical phenotypes, treatment responses, and outcomes of children with relapsing MOG-Ab-associated disease.

Our results show that the presence of MOG-abs strongly depends on the age at disease onset and that high MOG-ab titers were associated with a recurrent non-MS disease course.

Results MOG antibodies (median 1:2560; range 1:160-1:20 480) were detected in 19 children with ADEM. The majority of children showed a decline of serum MOG-IgG titres over time. Children with MOG antibodies did not differ in their age at presentation, sex ratio, the presence of oligoclonal bands, clinical symptoms or initial severity, apart from a higher CSF cell count ( p=0.038), compared with children without MOG antibodies. In addition, further relapsing demyelinating episodes associated with MOG antibodies were observed only in children with MOG antibodies. All 19 children with MOG antibodies had a uniform MRI pattern, characterised by large, hazy and bilateral lesions and the absence of atypical MRI features (eg, mainly small lesions, well-defined lesions), which was significantly different compared to that of children without MOG antibodies ( p=0.003; and p=0.032, respectively). In addition, children with MOG antibodies had involvement of more anatomical areas ( p=0.035) including the myelon characterised by a longitudinally extensive transverse myelitis ( p=0.003), more often a complete resolution of lesions ( p=0.036) and a better outcome ( p=0.038). Conclusions Patients with ADEM with MOG antibodies in our cohort had a uniform MRI characterised by large, bilateral and widespread lesions with an increased frequency of longitudinal extensive transverse myelitis and a favourable clinical outcome in contrast to children lacking MOG antibodies.

Pediatric patients presenting with clinical symptoms and MRI findings highly suggestive of NMO but with high and persisting MOG-IgG antibody titers are most likely to represent a distinct subgroup of acute demyelinating diseases with important clinical and therapeutic implications.

Children with MDEM and persisting MOG antibodies constitute a distinct entity of relapsing demyelinating events and extend the spectrum of MOG antibody-associated diseases.

Objective To determine the frequency and clinicalradiological associations of antibodies to myelin oligodendrocyte glycoprotein (MOG) and aquaporin-4 (AQP4) in children presenting with neuromyelitis optica (NMO) and limited forms. Methods Children with a first event of NMO, recurrent (RON), bilateral ON (BON), longitudinally extensive transverse myelitis (LETM) or brainstem syndrome (BS) with a clinical follow-up of more than 12 months were enrolled. Serum samples were tested for MOG-and AQP4-antibodies using live cell-based assays.Results 45 children with NMO (n=12), LETM (n=14), BON (n=6), RON (n=12) and BS (n=1) were included. 25/45 (56%) children had MOG-antibodies at initial presentation (7 NMO, 4 BON, 8 ON, 6 LETM). 5/45 (11%) children showed AQP4-antibodies (3 NMO, 1 LETM, 1 BS) and 15/45 (33%) were seronegative for both antibodies (2 NMO, 2 BON, 4 RON, 7 LETM). No differences were found in the age at presentation, sex ratio, frequency of oligoclonal bands or median EDSS at last follow-up between the three groups. Children with MOG-antibodies more frequently (1) had a monophasic course ( p=0.018) after one year, (2) presented with simultaneous ON and LETM ( p=0.004) and (3) were less likely to receive immunosuppressive therapies ( p=0.0002). MRI in MOG-antibody positive patients (4) less frequently demonstrated periependymal lesions ( p=0.001), (5) more often were unspecific ( p=0.004) and (6) resolved more frequently ( p=0.016). Conclusions 67% of all children presenting with NMO or limited forms tested positive for MOG-or AQP4-antibodies. MOG-antibody positivity was associated with distinct features. We therefore recommend to measure both antibodies in children with demyelinating syndromes.

Myelin oligodendrocyte glycoprotein (MOG) antibodies (abs) are present in one third of all children with an acute demyelinating syndrome (ADS). MOG-abs can be found in acute disseminated encephalomyelitis (ADEM), transverse myelitis, isolated optic neuritis (ON), or recurrent demyelinating diseases, such as multiphasic neuromyelitis optica spectrum disorders (NMOSD) without aquaporin-4 (AQP4) abs or multiphasic ADEM (MDEM), but rarely in children who subsequently develop multiple sclerosis (MS). The presence of MOG-abs is age dependent with the highest seropositivity rates found in young children and an episode of ADEM, whereas older children with MOG-abs present with ON, myelitis, or brainstem symptoms. MOG-abs, initially thought to be associated with a benign disease course, are found in a substantial proportion of children with relapsing episodes associated with high and persisting MOG-ab titers. This review describes, in particular, the increasing spectrum of phenotypes associated with MOG-abs with a focus on clinical characteristics, radiological features, and therapeutic aspects.

Neurological and cognitive sequelae are common in children with AC and underline the role of the cerebellum in cognition.