The sialic acid–Siglec interaction systems prevent the excessive and detrimental immune responses, yet the malfunction of interaction with Siglec3/CD33, Siglec-11, and Siglec-14 have been associated with neurodegenerative diseases such as Alzheimer’s disease (AD) [53,89,90,91]. The gene discussed is CD33; the disease is neurodegenerative disease.