Produces N-acetylneuraminic acid (Neu5Ac) and 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid (KDN) (PubMed:10749855, PubMed:27213289). Can also use N-acetylmannosamine 6-phosphate and mannose 6-phosphate as substrates to generate phosphorylated forms of Neu5Ac and KDN, respectively (PubMed:10749855). H2O + N-acetyl-D-mannosamine + phosphoenolpyruvate = N-acetylneuraminate + phosphate an N-acyl-D-mannosamine 6-phosphate + H2O + phosphoenolpyruvate = an N-acylneuraminate 9-phosphate + phosphate Ubiquitous. The disease is caused by variants affecting the gene represented in this entry.