This gene encodes a member of the membrane-spanning 4A gene family. Members of this nascent protein family are characterized by common structural features and similar intron/exon splice boundaries and display unique expression patterns among hematopoietic cells and nonlymphoid tissues. Alternative splicing of this gene results in several transcript variants, however, not all transcripts have been fully described.Synonyms: 4SPAN1, CD20 antigen-like 1, CD20L1, Four-span transmembrane protein 1, HDCME31P, MS4A4, Membrane-spanning 4-domains subfamily A member 4A