It is followed by a very timely review of current knowledge on the features of polysialic acid and their synthesizing enzymes (specially ST8SIA2), their functions in regulations of cell adhesion, ion channels, neurotrophins (such as BDNF) and catecholamine neurotransmitters (particularly dopamine), in light of several recent lines of evidence linking polysialic acid to schizophrenia (Sato and Kitajima, 2013). This evidence concerns the gene BDNF and schizophrenia.