MAGT1 and X-linked immunodeficiency with magnesium defect, Epstein-Barr virus infection and neoplasia: One immunodeficiency affects cytosolic Mg2+ levels, required for PLCγ1 activation, via mutations in the magnesium transporter 1 (MAGT1) in patients with X-linked immunodeficiency with magnesium defect, EBV infection, and neoplasia (XMEN) [47–51].