**2. Epidemiology**

The incidence of pediatric MS is unknown, but its estimated prevalence has been reported to be 1.35–2.5 per 100,000 children [4]. The gender ratio varies with the age of onset: in patients older than 10 years, the female-to-male ratio is similar to adults; there is female dominance. In children younger than 10 years old, the female-to-male ratio decreases. This difference may be due to hormonal influence or gender-specific genetic influence on immunological reactivity [5].
