Information in this section pertains to all global PEN® partners except where country flags are
visible. Click on the flag(s) for country-specific information. If a country flag is not listed, there is
no information specific to that country.
Disease Etiology
Multiple Sclerosis (MS) is a disorder of the central nervous system of unknown cause in which the body's immune system attacks myelin in the brain and spinal cord (1). Whether the disease manifests in repeated episodes of inflammation or as a chronic condition, it results in multiple scars or scleroses on the myelin sheath, leading to impairment or loss of nerve function.
MS is usually diagnosed between the ages of 15 and 40 and is more than three times as likely to occur