MAGT1 and X-linked immunodeficiency with magnesium defect, Epstein-Barr virus infection and neoplasia: MAGT1 is now confirmed as a non-catalytic subunit of the oligosaccharyltransferase complex and facilitates Asparagine (N)-linked glycosylation of specific substrates, making XMEN a congenital disorder of glycosylation manifesting as a combined immune deficiency.