Several studies have shown that patients with multiple sclerosis have significantly elevated expression of Pecam1 in serum and cerebrospinal fluid due to neuroinflammation and disruption of the blood cerebral barrier, and Pecam1 serum concentrations can be used as an indicator of multiple sclerosis blood-brain barrier disruption and a reliable marker of disease activity (Niezgoda and Losy, 2002). This evidence concerns the gene PECAM1 and multiple sclerosis.