Sialomucins are a heterogeneous group of secreted or membrane-associated mucins that appear to play 2 key but opposing roles in vivo: first as cytoprotective or antiadhesive agents, and second as adhesion receptors. CD164 is a type I integral transmembrane sialomucin that functions as an adhesion receptor (Watt et al., 1998 [PubMed 9680353]; Forde et al., 2007 [PubMed 17077324]).[supplied by OMIM, Aug 2008]