Paediatric Acquired Demyelinating Syndromes

Paediatric acquired demyelinating syndromes (ADS) are characterised by neurological deficits persisting for at least 24 hours, involving the optic nerve, spinal cord or brain with a clinical spectrum of diagnoses including multiple sclerosis (MS), neuromyelitis optica spectrum disorder (NMOSD) and MOG-Ab associated disease (MOGAD). Important strides have been made in delineating MS from other ADS subtypes over the past decade, including the discovery of serum aquaporin-4 (AQP4) and Myelin oligodendrocyte glycoprotein (MOG) antibodies (Ab). Both genetic (e.g. human leukocyte antigen, HLA-DRB1*1501 allele) and environmental risk factors (e.g. low serum vitamin D levels and prior exposure to Epstein–Barr virus) may contribute to risk of MS in children. Some of these risk factors not only confer increased susceptibility to MS but may also affect the disease course. Paediatric AQP4-Ab NMOSD is a rare disease worldwide but variations in incidence/prevalence have been described among different geographic regions and ethnicities. One-third of children who present with an ADS have MOG-Ab, and approximately half of patients with MOG-Ab have a relapsing disease course. It seems there is no racial or gender predominance in MOGAD, which is in contrast to the female and non-white predominance seen in both MS and NMOSD.‎ In this review, we examine the current literature regarding the epidemiology and demographics of these different ADS entities with a particular focus on the genetic and environmental risk factors for MS in children. While insights into disease pathophysiology in paediatric ADS have led recent therapeutic advances, well designed, collaborative large scale epidemiological studies are likely to provide the critical next step to a personalised approach to these conditions