Sialic acid acetylesterase

Sialic acid acetylesterase (SIAE) is an enzyme that produces 9-O acetylated sialic acid e.g. in mammals. It down-regulates B lymphocyte antigen receptor signaling (involving CD22), and is required for immunological tolerance e.g. in mice.

Loss of function mutations in SIAE are much more frequently found in humans with autoimmune diseases especially rheumatoid arthritis and type 1 diabetes.