Cytidine monophospho-N-acetylneuraminic acid hydroxylase (Cmah) is an enzyme that is encoded by the CMAH gene. In most mammals, the enzyme hydroxylates N-acetylneuraminic acid (Neu5Ac), producing N-glycolylneuraminic acid (Neu5Gc). Neu5Ac and Neu5Gc are mammalian glycans that compose the glycocalyx, especially in sialoglycoproteins, which are part of the sialic acid family. The CMAH equivalent in humans is a pseudogene (CMAHP); there is no detectable Neu5Gc in normal human tissue. This deficiency has a number of proposed effects on humans, including increased brain growth and improved self-recognition by the human immune system. Incorporation of Neu5Gc from red meat and dairy into human tissues has been linked to chronic disease, including type-2 diabetes and chronic inflammation.
