Notably, the most upregulated plasma protein within the proinflammatory pathway in POTS was beta-2-microglobulin (B2M), which is a component of the major histocompatibility complex class I. Ongoing inflammation is associated with elevated levels of β2M25, likewise, increased levels of B2M have been reported in several autoimmune diseases. The gene discussed is B2M; the disease is autoimmune disease.