Amelogenin, X-Linked (AMELX) belongs to the amelogenin family of extracellular matrix proteins. Amelogenins have a role biomineralization during tooth enamel development. AMELX gene mutations cause X-linked amelogenesis imperfecta. AMELX regulates the formation of crystallites during the secretory stage of tooth enamel development. AMELX is transiently but amply expressed by ameloblasts during tooth development. Amelogenin is the principal protein in developing dental enamel.