Disability progression was linked to deep GM, temporal pole and lateral orbitofrontal atrophy, while learning difficulties were associated with lateral occipital and parietal atrophy.<h4>Interpretation</h4>Brain lesions at onset and their persistence, relapsing disease and MOG-Ab positivity are key risk factors for GM atrophy and clinical impairment in paediatric MOGAD. This evidence concerns the gene MOG and Atrophy.