Risk factors for multiple sclerosis in 302 children presenting with CNS demyelination to health-care facilities in Canada included HLA-DRB1*15 alleles, previous infection with Epstein-Barr virus, and low serum 25-hydroxyvitamin D. MRI brain lesions, and CSF oligoclonal bands are probable precursors of multiple sclerosis (MS). Children with a normal MRI are likely to have a monophasic illness. At follow-up, 63 (21%) were diagnosed with MS after a median of 127 days. [1]